JPH03176955A - Scanning type electron beam device - Google Patents

Abstract

PURPOSE:To obtain a smell-sized device with a magnetic field deflector and an electrostatic deflector by providing the electrostatic deflector made of a magnetic shield material so as to surround an electron beam passage between a sample and a focusing lens immediately above the sample. CONSTITUTION:When the observation multiplying factor is set to a high multiplying factor by a control circuit 13, a switching signal is fed to a switching unit 4 from the control circuit 13, and the scanning signal generated by a scanning signal generator 12 is fed to deflectors via amplifiers 6, 18 and a reverse amplifier 17 (19). An electron beam is deflected by a deflector 7 to scan a sample 8. Since the deflector 7 is provided between an objective lens 5 and the sample 8, the incorrect deflection by the interplying magnetic field of the electron beam is prevented. When the observation multiplying factor is set to a low multiplying factor, the electron beam is deflected by a magnetic field deflector 4, and the sample 8 is two-dimensionally scanned. The incorrect deflection of the electron beam is prevented by the magnetic shield effect of the deflector 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a scanning electron beam equipped with a deflector for irradiating an electron beam onto a desired position on a sample and for scanning an electron beam on a sample. Regarding beam equipment.

[Prior Art] Conventionally, a scanning Auger electron spectrometer having a configuration as shown in FIG. 2 has been known. In Fig. 2, 1 is an electron gun, 2 is a focusing lens, 4 is an electromagnetic deflector consisting of deflection coils 3x and 3y, 5 is an objective lens, 8 is a sample, 9 is an analyzer, 10 is an amplifier, and 11 is a cathode ray tube. , 12 is a scanning signal generator, 13 is a control circuit, and 15 is a deflection coil power supply.

The electron beam emitted from the electron gun 1 is focused onto the sample 8 by a focusing lens 2 and an objective lens 5. The scanning signal generator 12 generates a scanning signal based on the observation magnification and scanning speed set in the control circuit 13, and the scanning signal (sawtooth wave) is supplied to the deflection coil power source. From the deflection coil power supply, the deflection coil 3x,
An excitation current is supplied to 3y. As a result, sample 6
The electron beam irradiated to the sample is deflected, and the sample is two-dimensionally scanned by the electron beam.

Due to the scanning of the electron beam, Auger electrons and the like emitted from the sample are collected and spectrally analyzed by the analyzer 9 and detected. The detection signal is then supplied to a cathode ray tube 11 via an amplifier 10.

Since the cathode ray tube 11 is swept in synchronization with the scanning signal generated by the scanning signal generator 12, a two-dimensional Auger electron image or the like is displayed on the cathode ray tube 11.

[Problems to be Solved by the Invention] Now, in the scanning Auger electron spectrometer having the above-described configuration, in order to scan the electron beam on the sample, a magnetic field deflector 4 consisting of deflection coils 3X and 3y is provided. There is. Since the magnetic field type deflector 4 can largely deflect the electron beam, it is particularly suitable for low-magnification image observation in which a wide area on a sample is scanned for observation.

However, in the case of the magnetic field type deflector, since the frequency response of the deflection coil is poor, the deflection coil 3x is connected to the scanning signal generator 12 via the deflection coil power supply 15.

Even if the deflection signal supplied to 3y is a precise sawtooth wave, distortion of the deflection magnetic field may occur due to the response delay of the coil. In particular, when high-speed scanning on the order of TV rate is performed, since a sawtooth wave with a fast period is used, the influence of distortion of the deflection magnetic field is significant. Therefore, when performing point analysis by fixing the electron beam at a desired observation point specified during the high-speed scanning, the desired current (constant current) value in the scanning signal obtained during the scanning is applied to the deflection coil. Even if the electron beam is given, the electron beam may not be deflected to the desired point δ1 due to an error caused by the frequency response of the deflection coil.

Therefore, an electrostatic type deflector with good frequency response is sometimes used in place of the magnetic field type deflector with poor frequency response, but the electrostatic layer deflector can be used within a range of applied voltage that is easy to handle. There is a problem in that the electron beam cannot be deflected as greatly as a magnetic field type deflector.

Therefore, a scanning electron beam device including the magnetic field type deflector and an electrostatic layer deflector has been proposed, but in this case, there is a problem that the electron optical system becomes larger.

Furthermore, in Auger electron spectrometers and the like, a magnetic shield tube (not shown) is installed between the objective lens and the sample to prevent the electron beam irradiated onto the sample from being improperly deflected by a disturbance magnetic field. However, there is a problem in that the installation of the magnetic shield cylinder further increases the size of the optical system.

SUMMARY OF THE INVENTION An object of the present invention is to provide a compact scanning electron beam device equipped with a magnetic field deflector and an electrostatic layer deflector in consideration of the above-mentioned problems.

[Means for Solving the Problems] The present invention includes a focusing lens for focusing an electron beam emitted from an electron gun onto a sample, and a magnetic field deflector for scanning the electron beam on the sample. A scanning electron beam device characterized in that an electrostatic layer deflector made of a magnetic shielding material is provided to surround an electron beam path between the sample and a focusing lens directly above the sample. Device.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is an apparatus configuration diagram for explaining one embodiment of the present invention. In FIG. 1, the same components as in FIG. 2 are given the same numbers and their explanations are omitted. The embodiment shown in FIG. 1 is different from the conventional example in that an electrostatic layer deflector 7 made of a magnetic shielding material is provided between the objective lens and the sample.
A switch 14 is provided to select and use either the electrostatic deflector 7 or the magnetic field deflector 4.

The electrostatic layer deflector 7 includes an X-direction deflection plate 6x (6x-not shown) made of a magnetic shielding material, and a magnetic shield plate 61 arranged perpendicular to the X-direction deflection plate. '6
a Y-direction deflection plate 6y (6y-not shown) surrounding the electron beam path and made of a magnetic shielding material; and a magnetic shielding plate 6m arranged perpendicular to the Y-direction deflection plate. 6 m- surround the electron beam path. Here, the deflection plate to which a voltage is applied and the shield plate at ground potential are spaced apart from each other by about 0.5 to 1 mm for insulation.

In the apparatus configured as described above, when the observation magnification is set to a high magnification, for example, 200 times or more in the control circuit 13, a switching signal is supplied from the control circuit 13 to the switching device 14, and the scanning signal generator 12 The generated scanning signal is transmitted to amplifiers 16, 1g, and inverting amplifier 17.
A switch is switched so that the light is supplied to each deflection plate via 19.

Here, the scanning signal, for example in the X direction, is supplied to the electrostatic deflection plate 6
x-. Similarly, the scanning signal in the Y direction is sent to amplifier 1.
8 to the electrostatic deflection plate 6y on the positive side, and also supplied to the electrostatic deflection plate 6y- on the negative side (not shown) via an inverting amplifier 17 (not shown).

Thereby, the electron beam is deflected by the electrostatic deflector 7, and the sample is scanned by the electron beam.

Now, in the present invention, the electrostatic layer deflector 7 having the above-described configuration is provided between the objective lens and the sample. Therefore, the electron beam irradiated onto the sample is prevented from being improperly deflected by the disturbance magnetic field, so that the sample can be accurately irradiated and scanned with the electron beam.

On the other hand, when the observation magnification is set to a low magnification, for example, less than 200 times, in the control circuit 13, a switching signal is supplied from the control circuit 13 to the switching device]4, and the scanning signal generated in the scanning signal generator 12 is A signal is provided to the deflection coil power supply.

An excitation current is supplied from the deflection coil power supply to the deflection coil 3x3y. Thereby, the electron beam is deflected by the magnetic field deflector 4, and the sample is scanned two-dimensionally. In this case as well, the magnetic shielding effect of the electrostatic layer deflector 7 prevents the electron beam irradiated onto the sample from being improperly deflected by the disturbance magnetic field, making it possible to accurately irradiate and scan the sample. I can do it.

Note that the above-described embodiment is only one embodiment of the present invention, and the present invention can be implemented with various modifications. For example, in the embodiment described above, the electron beam path is surrounded by an X-direction deflection plate made of a magnetic shielding material and a magnetic shielding plate arranged orthogonally to the X-direction deflection plate, and the electron beam path is surrounded by a magnetic shielding material. The formed Y-direction deflection plate and the Y-direction deflection plate
The electron beam path is surrounded by magnetic shield plates arranged in a direction perpendicular to the direction deflection plate, and each is placed along the electron beam path to create an electrostatic layer deflector, or the electrostatic layer The deflector includes an X-direction deflection plate made of a magnetic shielding material and a Y-direction deflection plate made of a magnetic shielding material arranged perpendicular to the X-direction deflection plate so as to surround the electron beam path. It may be formed.

[Effects of the Invention] As is clear from the above description, the present invention includes a focusing lens for focusing an electron beam emitted from an electron gun onto a sample, and a focusing lens for scanning the electron beam on the sample. In the scanning electron beam device equipped with a magnetic field deflector, an electrostatic layer deflector made of a magnetic shielding material is provided to surround the electron beam path between the sample and the focusing lens directly above the sample. , a compact scanning electron beam device including a magnetic field deflector and an electrostatic layer deflector is provided. In addition, since the electrostatic layer deflector is made of a magnetic shielding material, the electron beam irradiated onto the sample will not be improperly deflected by a disturbance magnetic field, so the sample can be accurately irradiated or scanned by the electron beam. .

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of an apparatus for explaining a one-fire embodiment of the present invention, and Figure 2 is a diagram for explaining a conventional example. 1; Electron gun 2: Focusing lens 3x: X-direction deflection coil 3y: Y-direction deflection coil 4: Magnetic field deflector 5: Objective lens 6x, 6x-
: X direction deflection plates 6y, 6y : Y direction deflection plates 61, 61-: Magnetic shield plates 6m, 6m: Magnetic shield plates 7: Electrostatic layer deflector 8: Sample 9: Analyzer 10: Amplifier 11: Cathode ray tube 11a, llb: Cathode ray tube deflector 12: Scanning signal generator 13: Control circuit 14: Switcher 15: Deflection coil power supply 0

Claims (1)

[Claims] In a scanning electron beam device equipped with a focusing lens for focusing an electron beam emitted from an electron gun onto a sample, and a magnetic field deflector for scanning the electron beam on the sample, 1. A scanning electron beam device comprising an electrostatic deflector made of a magnetic shielding material so as to surround an electron beam path between the focusing lens and the focusing lens.