JPH065237A - Position detector and electron microscope device including the same - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the operability of a position detector for detecting the deflection of an electron beam used in a scanning transmission electron microscope or the like. [Structure] Light 4 emitted by a charged particle beam 1 incident on a scintillator 2 is guided to the outside of a vacuum and is sent to a light guide 6 and a photomultiplier tube 7 installed outside the vacuum by using an optical lens 5. The light guide 6 and the photomultiplier tube 7 are integrated, a rotation mechanism 11 is provided, and the entire detector is surrounded by a light shield 21. [Effect] Since the detector is at atmospheric pressure, replacement and maintenance work can be performed very easily. Further, it is possible to easily change the direction of the detector according to the deflection direction of the electron beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a position detector for an electron beam attached to a scanning transmission electron microscope, and for example, a division for detecting a deflection due to a Lorentz force applied when the electron beam passes through a sample. Type detector.

[0002]

2. Description of the Related Art A scanning transmission electron microscope is capable of narrowing an electron beam to a very small size. It is possible to investigate various magnetic structures with very high resolution. The deflection of the electron beam is detected by taking the difference signal from the split position detector. This is Ultra Microscopy, Volume 3 (1978) 203-214, (Ultr
amicroscopy 3 (1978) 203-214, Thedirec
t determination of magnetic domain wall profiles
by differentialphase contrast electron microscop
As shown in y), the scintillator divided into two is irradiated with the electron beam, and the light emitted there is divided into each photomultiplier tube by the light guide and introduced.
Amplify. The difference between the signals is detected as a position signal of the electron beam. This position signal corresponds to the deflection angle of the electron beam, which can correspond to the magnitude and orientation of the magnetic induction in the sample.

[0003]

The prior art is an excellent method capable of detecting a minute position change of the electron beam.
There are problems in the following points.

First, in the prior art, the scintillator and the light guide are integrated, and since they are installed in a vacuum, when performing maintenance or replacement of the detector, the electron microscope apparatus The vacuum must be broken and the operability is very poor.

Second, although the direction of deflection of the electron beam does not necessarily coincide with the direction in which the detector has good sensitivity, in the prior art, the scintillator is fixed in a vacuum and the direction of the detector can be easily changed. I can't.

An object of the present invention is to improve the operability when performing maintenance or replacement of the split type detector.
Another object of the present invention is to provide means capable of easily matching the sensitive direction of the detector and the deflected direction of the charged particle beam.

[0007]

According to the present invention, a light emitted from a scintillator is guided to the outside of a vacuum, and further guided to a divided light guide and a photomultiplier tube by an optical lens to detect the detector outside the vacuum. It is the one that can be operated.

Further, by attaching a rotating mechanism to the detector, the deflection direction of the charged particle beam and the direction with good sensitivity of the detector can be made to coincide with each other.

[0009]

[Operation] Since the main part of the detector is outside the vacuum, maintenance of the detector and
Can be exchanged. Further, since the rotation mechanism is provided, the direction with good sensitivity of the detector can be easily oriented to the deflection direction of the electron beam.

[0010]

FIG. 1 shows an embodiment of the position detector according to the present invention. In the figure, the electron beam 1 incident on the scintillator 2 converts its energy into light,
The light is transmitted through the light transmitting window 3. The light 4 is imaged on the light incident surface of the light guide 6 by the optical lens. The light guide 6 is divided into four, and the light 4 entering each light guide 6 has a photomultiplier tube 7, a bleeder 8, and a preamplifier 1.
It is amplified by 5 and sent to the arithmetic circuit. The optical lens 5 and the stage 13 can be moved up and down, and can be adjusted so that the light 4 generated by the scintillator 2 is imaged on the light incident surface of the light guide 6. Light guide 6, photomultiplier tube 7, preamplifier 15
Can be horizontally moved and rotated by the xyθ goniometer 11, so that the incident position of the light 4 can be moved to the optimum position of the detector. Further, the sensitivity of the detector is best in the direction perpendicular to the line that divides the light guide 6, so that it can be rotated in accordance with the direction in which the irradiation position of the electron beam 1 changes. These movements can be adjusted from the outside of the shield 21 by the universal joint 10 and the knob 12 while watching the signal output.

FIG. 2 shows an example in which the split position detector described above according to the present invention is replaced with a semiconductor position detector. Since the inside of the shield 21 is at atmospheric pressure, replacement work can be performed without breaking the vacuum of the electron microscope. Further, the replacement work only needs to replace the light guide 6, the photomultiplier tube 7, and the preamplifier 15, and the work can be carried out very easily. After the replacement, the stage 4 is vertically moved so that the light 4 generated by the scintillator 2 is adjusted to form an image on the light incident surface of the semiconductor position detector 24, and the cable 17 is connected to enable the use.

FIG. 3 is a schematic diagram of a system in which the position detector described in FIGS. 1 and 2 is incorporated in an electron microscope. The electron beam 1 is deflected by the deflector 104 controlled by the beam deflection circuit 109, and scans the sample 105. The position detector 108 detects the deflection of the electron beam 1 due to the Lorentz force received when passing through the sample 105. Here, since the objective lens 106 faces the deflection center of the electron beam by the deflector 104, a signal due to beam deflection does not appear in the position detector 108. Further, the imaging lens 107 can adjust the size of the spot of the electron beam incident on the position detector 108. The position signal calculation circuit 110 calculates the difference between the respective divided signals obtained by the position detector 108, and uses this difference as the position signal. Then, the information is displayed on the display device 111 together with the information on the beam irradiation position from the beam deflection circuit 109. on the other hand,
A scanning transmission electron microscope image can also be obtained by taking the sum of the signals in the position signal calculation circuit 110.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to these and various modifications can be made. For example, although the embodiment has been described as applied to a scanning transmission electron microscope, it can be applied to a conventional transmission electron microscope or a position detector used in an ion beam apparatus.

[0014]

According to the present invention, a position detector having a rotating function can be installed outside the vacuum device to obtain a position detector with good operability.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a position detector according to the present invention.

FIG. 2 is an explanatory diagram in which a split type detector is replaced by a semiconductor position detector according to the present invention.

FIG. 3 is an explanatory diagram in which the position detector according to the present invention is incorporated into a scanning transmission electron microscope.

[Explanation of symbols]

1 ... Electron beam, 2 ... Scintillator, 3 ... Light transmission window, 4
... light, 5 ... optical lens, 6 ... light guide, 7 ... photomultiplier tube, 8 ... bleeder, 10 ... universal joint, 11 ... xyθ goniometer, 12 ... knob, 13 ...
Stage, 15 ... Preamplifier.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokushige Igarashi 1-280, Higashi Koigokubo, Kokubunji, Tokyo Metropolitan Research Center, Hitachi, Ltd.

Claims (3)

[Claims] 1. A charged particle is produced by irradiating a scintillator with a charged particle beam and emitting light to an independent light guide and a photomultiplier tube, which are divided into two or four, and take the difference between the amplified signals. In a division type position detector for detecting a minute position change of a line, the light emitted from the scintillator is imaged on the light guide by using an optical lens, so that the light guide and the photomultiplier tube are A position detector characterized by being separated from the scintillator. 2. The position detector according to claim 1, comprising a mechanism capable of rotating the light guide and the photomultiplier tube. 3. An electron microscope apparatus equipped with the position detector according to claim 1.