JPH11144667A - Mirror electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To photograph an inclined image without inclining a sample and stereoscopically observe the sample by assembling an electrostatic deflector off the electron beam path along the rotation symmetrical axis of a mirror electrode, and inclining the electron beam path. SOLUTION: An electron beam 2 emitted from an electron gun 1 is focused by focusing lenses 3a, 3b and is fed to a magnetic prism 4a forming a Castaing- Henry deflector, electrodes 4a, 4c, 4e for mirror-reflecting the electron beam 2 and an electrostatic deflector 4d. When the electrostatic deflector 4d is not operated, the electron beam 2 is vertically fed to the sample 7. When the electrostatic deflector 4d is operated, the electron beam 2 is fed to the sample at an incidence angle, and it has the same effect as inclining the sample 7 toward the electron beam 2. The sample 7 can be two-dimensionally moved by sample drive devices 8, 9, the movable quantity can cover the whole area of a semiconductor wafer, and the electron beam 2 can be deflected in an optional direction by the electrostatic deflector 4d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron microscope, and more particularly to a mirror type electron microscope which forms an image by using mirror reflection on a sample.

[0002]

2. Description of the Related Art A mirror type electron microscope is a Ludwig Reimer;
Transmission Electron Microscopy, Springer-Verlag
As described in 1993, this is a known technique since the 1930s. Also, RMTromp MCReuter; Design of
a new photo / low-energyelectron microscope for s
As described in urface studies, Ultramicroscopy 36 (1991) 99-106, a structure in which a mirror electrode and a magnetic field lens are combined has an example as an application of the mirror electron microscope.

[0003]

In a mirror-type electron microscope, a sample is placed on the bottom of a mirror electrode. This mirror electrode
The same voltage as the acceleration voltage is applied for use as a deceleration electrode. Therefore, the mechanism for mechanically tilting the sample must be complicated in view of the withstand voltage, and
It is even more difficult to tilt a large sample in any direction at a large angle.

[0004]

In the present invention, an electrostatic deflector is incorporated so as to deviate from the electron trajectory along the rotational symmetry axis of the mirror electrode, and the electron beam trajectory is tilted, so that the same effect as the sample tilt is obtained. Get.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a mirror electron microscope according to the present invention.

[0006] The electron beam 2 emitted from the electron gun 1 is converged by the converging lenses 3 a and 3 b and is incident on a Kasten-Henry deflector 4. The Kasten-Henry deflector 4 includes a magnetic prism 4a for changing the direction of an incident electron beam, electrodes 4b, 4c, 4e for mirror-reflecting the electron beam, and an electrostatic deflector 4d.

The electron beam 2 is bent 90 degrees by the magnetic prism 4a and travels to the electrode 4b. The light is mirror-reflected by the electrodes 4b, 4c and 4e. A voltage substantially equal to the acceleration voltage is applied to the electrode 4e. The sample 7 is on the electrode 4e. The reflected electron beam 2 has the surface information of the sample 7 and enters the magnetic prism 4a again. The electron beam 2 is bent again by the magnetic prism 4a and travels to the projection lenses 5a and 5b. After the magnification is adjusted by the projection lenses 5a and 5b, an image is formed on the fluorescent screen 6.

Next, the operation of the electrostatic deflector 4d will be described. When the electrostatic deflector 4d is not operating, the light is perpendicularly incident on the sample 7, but when the electrostatic deflector 4d is activated, the incidence of the electron beam 2 on the sample 7 is angled. That is, there is an effect that the sample 7 is inclined with respect to the electron beam 2.

The sample 7 and the electrode 4e are held by a sample driving device 8. The sample driving device 8 moves the sample 7 in one dimension.
Can be moved. The sample driving device 8 is held by the sample driving device 9. The sample driving device 9 can move the sample driving device 8 and the sample in a one-dimensional direction different from that of the sample driving device 8. The sample 7 can be moved two-dimensionally by the sample driving device 8 and the sample driving device 9. The movable amount of each of the sample driving devices 8 and 9 is an amount that can cover the entire area of the semiconductor wafer.

FIG. 2 is a plan view of the electrostatic deflector 4d.
The electrostatic deflector 4d is constituted by electrostatic deflectors 10a, 10b, 10c and 10d. Electrostatic deflection plates 10a and 10c, 1
A pair of 0b and 10d performs a deflection operation. By arbitrarily combining two pairs of deflection plates, the electron beam 2 can be deflected in an arbitrary direction.

[0011]

According to the present invention, it is possible to take a tilted image without tilting the sample, and it is possible to perform three-dimensional observation of the sample.

[Brief description of the drawings]

FIG. 1 is a schematic view of a mirror electrode of a mirror electron microscope according to the present invention.

FIG. 2 is a plan view of a deflection electrode for a mirror electrode according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Electron beam, 3a, 3b ... Convergent lens, 4
... Kasten-Henry type deflector, 5a, 5b ... Projection lens,
6 fluorescent plate, 7 sample, 8, 9 sample drive device, 10
a, 10b, 10c, 10d ... electrostatic deflection plates.

Claims (2)

[Claims] An electron gun for generating an electron beam; an electron optical system including a converging lens, a magnetic prism, a mirror electrode, and a projection lens; and a means for visualizing an image formed by the electron gun. A mirror type electron microscope comprising: a sample driving device capable of holding and moving a sample; and an electrostatic deflector incorporated in the mirror electrode. 2. A mirror-type electron microscope, wherein a semiconductor wafer can be held by the sample driving device.