JPS6342460Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an electron microscope equipped with an X-ray analyzer.

It is common practice to use the objective lens of a transmission imaging electron microscope with strong excitation and use it as a high-resolution scanning electron microscope. , often performs minute elemental analysis in samples. In this case, an energy dispersive X-ray spectrometer is usually used as a means for X-ray analysis. This type of X
A line spectrometer uses a semiconductor detector that is always maintained at a low temperature as its detection element. This semiconductor detector tends to deteriorate its X-ray detection characteristics when a high-energy electron beam is incident on it, so it is necessary to prevent the electron beam that is incident on the sample and reflected from entering the semiconductor detector. Become. By the way, when a transmission imaging electron microscope is used as a scanning electron microscope, the magnetic field of the objective lens is conveniently maintained at a strong excitation level, so that the reflection from the sample inserted approximately at the center of the objective lens magnetic field is The electrons are deflected by the magnetic field of the objective lens, and the number of reflected electrons that enter the semiconductor detector becomes extremely small. However, transmission imaging electron microscopes have various observation modes, and the excitation of the objective lens may be made extremely weak or zero. In such a case, it is necessary to remove the semiconductor detector or insert a shutter into its light-receiving surface, but if you forget to do this, a large amount of backscattered electrons will enter the semiconductor detector and damage it. An accident will occur.

The purpose of the present invention is to prevent damage to semiconductor detectors from reflected electrons.

The present invention provides an apparatus configured to guide X-rays generated from a sample inserted into the approximate center of an objective lens magnetic pole piece to a detection element of an energy dispersive X-ray spectrometer, in which the excitation intensity of the objective lens is below a certain value. and a means for supplying a deflection signal of a certain value or more to a deflection coil for deflecting the electron beam incident on the objective lens based on the detection signal from the means. There is.

The present invention will be explained in detail below using the drawings.

FIG. 1 shows an embodiment of the device of the present invention.
FIG. 2 is an enlarged view of the main part. In the figure, the path of the electron beam 2 emitted from the electron gun 1 is in the scanning image mode, and in this mode, the path of the electron beam 2 emitted from the electron gun 1 is in the scanning image mode. Two lens magnetic fields 6a and 6b are formed. The electron beam 2 that irradiates the sample 5 is narrowly focused on the sample surface by the focusing lens magnetic field 7 and the objective lens magnetic field 6a, and from the sample irradiation area, not only the X-rays 8 but also reflected electrons 9, secondary electrons, etc. are emitted. Occur. The position of the electron beam that irradiates the sample is determined by the deflection power supply 1.
The zero output can be changed arbitrarily by the deflection coil 12 supplied through the terminal a of the switch 11.
The deflection coil 12 is connected to a constant current power source 13 via a terminal b of a switch 11, and the switch 11 is switched by a switch control circuit 14. The switch control circuit 14 also includes a differential amplifier 16 to which the output is applied via the changeover switch 15.
controlled by. That is, when the output voltage of the lens power source 17 becomes lower than the reference power source 18, the differential amplifier 16 generates an output signal and switches the switch 11 to the b terminal. Reference numeral 19 denotes an energy dispersive X-ray spectrometer, and the X-ray spectrometer 19 is composed of a collimator 20, a window or shutter mechanism 21, a support tube 22, and a semiconductor detector 23, and is arranged near the sample 5. . The changeover switch 15 is turned on when the X-ray spectrometer is set to the X-ray detection state, and although this operation may be done manually, it is preferable to link it with operations such as removing the X-ray spectrometer.

In the apparatus configured as described above, the electron beam 2
The X-rays 8 generated from the sample 5 by the irradiation pass through the collimator 20, window or shutter mechanism 21, enter the semiconductor detector 23 in the support tube 22, are converted into electrical signals, and are converted into electrical signals by a measurement circuit (not shown). Elemental analysis is performed by However, since the reflected electrons 9 are deflected by the lens magnetic field 6a, they rarely pass through the collimator 20 like X-rays. Therefore, as long as scanning image mode observation is performed, damage to the semiconductor detector 23 caused by the backscattered electrons 9 does not pose a problem.

Next, when the operator removes the semiconductor detector 23 or weakens the output of the lens power supply of the objective lens below a certain value in order to perform observation in a mode other than the scanning image mode without inserting a shutter, the excitation intensity of the objective lens becomes different. detected by the dynamic amplifier 16;
The output signal is applied to the switch control circuit 14 via the changeover switch 15, and the switch 11 is connected to terminal b.
Connect to. As a result, a large value of deflection current is supplied from the constant current power source 13 to the deflection coil 12 to largely deflect the electron beam 2 so that the sample 5 is not irradiated with the electron beam. Therefore, it is possible to prevent reflected electron beams generated from the sample from entering the semiconductor detector 23 and damaging it. At this stage, the operator shifts the mounting position of the support tube 21, which is composed of a semiconductor detector, etc., or inserts a shutter into its detection surface, then turns the switch OFF, and then performs the desired observation. conduct.

As described above, the present invention protects the energy dispersive X-ray spectrometer incorporated in a transmission imaging electron microscope from backscattered electrons by a simple means, and provides an electron microscope equipped with an X-ray analyzer that is less likely to malfunction. do.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the device of the present invention, and FIG. 2 is an enlarged view of the main parts of the embodiment of the device shown in FIG. 1: Electron gun, 2: Electron beam, 3, 4: Objective lens magnetic pole piece, 5: Sample, 7: Focusing lens magnetic field, 8: X
line, 9: reflected electron, 10: deflection power supply, 13: constant current power supply, 14: switch control circuit, 16: differential amplifier, 17: lens power supply, 18: reference power supply, 1
9: X-ray spectrometer, 20: collimator, 21: shutter mechanism, 22: support tube, 23: semiconductor detector.

Claims (1)

[Scope of utility model registration request] In a device configured to guide X-rays generated from a sample inserted approximately at the center of an objective lens magnetic pole piece to a detection element of an energy dispersive X-ray spectrometer, the excitation intensity of the objective lens is below a certain value. and means for supplying a deflection signal of a certain value or more to a deflection coil for deflecting an electron beam incident on an objective lens based on a detection signal from the means. Electron microscope with analytical equipment.