JPS58200184A - Detecting device for reflected electron - Google Patents

Abstract

PURPOSE:To simplify the structure of the titled device and to enable an operation of high performance for a long time, by using a detecting element formed of a light element member. CONSTITUTION:An irradiation electron beam 9 passes through the hole of a pole piece 10a of an upper object lens above a stop plate 7 and then through the hole of the plate 7 and that of a detecting plate 8, and moves for scanning a sample 11, while irradiating the same. From the sample 11 a reflected electron 12 is generated, and it is detected by the plate 8. A transmission electron 13 which transmits through the sample 11 and advances straight passes through the hole of a pole piece 10b of a lower object lens and forms the image of the sample on a fluorescent plate. In this case, the detecting plate 8 is made of a light element metal such as aluminum or beryllium, and a reflected electron image formed when the sample 11 is scanned by the finely-restricted irradiation electron beam 9 is detected by the plate 8 and displayed by a monitoring device 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a backscattered electron detection device installed in a sample chamber of a transmission electron microscope, and particularly relates to an improvement in its detection section.

A portion of the electron beam that irradiates the sample passes through the sample, and a portion becomes reflected electrons and is scattered. The backscattered electrons reflected and scattered by this sample are detected by a backscattered electron detector installed around the electron beam path just above the sample. The detection section of a conventional reflection electron detector is constructed using a semiconductor element that has good absorption efficiency of reflected electrons. In addition, in the mode to obtain a backscattered electron image of the sample, the sample current is reduced to 10''''A or less, but in the mode to obtain a transmitted electron image of the sample, the sample current is reduced to 10-7 to 1O-8A. It is increasing.

When a large amount of electron beam is reflected by a thick film sample or the like in this mode for obtaining a transmitted electron image, the semiconductor element is destroyed by this large amount of reflected electrons. Conventionally, in order to avoid this, it was necessary to remove the backscattered electron detector from the electron beam path except in the backscattered electron image detection mode.

Further, a backscattered electron detector using a semiconductor element has a complicated structure and is expensive. That is, the conventional backscattered electron detector requires a mechanism for moving it depending on the measurement mode, and has the disadvantage that it is expensive.

The purpose of this project is to eliminate the drawbacks of the conventional technology and provide a backscattered electron detector that is inexpensive and has a long life.The main feature of this project is to eliminate the drawbacks of the conventional technology and provide a backscattered electron detector that is inexpensive and has a long life. The reason is that it was configured using .

FIG. 1 is an explanatory diagram of a backscattered electron detection apparatus which is an embodiment of the present invention, and shows a cross-section of the vicinity of a sample chamber 5 of a transmission electron microscope. A cylindrical body 3 is inserted through an O-ring 2 into a horizontal hole provided in a side wall 1 of a transmission electron microscope. A diaphragm plate 7 and a detection plate 8 are attached to the upper surface of the projection at the tip of the cylinder 3 via an insulator 5, and are fixed with screws 6. A small hole is provided at each tip of the aperture plate 7 and the detection plate 8 to allow the irradiation electron beam 9 to pass therethrough.

The irradiated electron beam 9 passes through the hole in the pole piece 10a of the upper objective lens located above the aperture plate 7, and then passes through the hole in the aperture plate 7 and the hole in the detection plate 8, irradiating the sample 11 while scanning. do. Reflected electrons 12 are generated in the sample 11 and detected by the detection plate 8, and the transmitted electrons 13 that have passed through the sample 11 and proceeded straight pass through the hole in the pole piece 10b of the lower objective lens and form a sample image on the fluorescent plate. make.

The reflected electron signal from the sample surface detected by the detection plate 8 is sent to the terminal plate 14. Lead wire 15a, hermetic seal 16. The signal is transmitted to the connection terminal 18 via the lead wire 15b. The signal input to this connection terminal 18 is amplified by an amplifier 19 and sent to an observation device 20, where it is displayed. Note that 17 is an O-ring that makes the periphery of the hermetic seal 16 airtight, and the water metal 21 that holds the hermetic seal 16 is fixed to the cylinder body 3 with a set screw 4, and is attached to the side wall 1 with a screw 22. Fixed. Furthermore, when the switch of the observation device 20 is switched, a sample image is generated on the fluorescent plate by the transmitted electron beam 15 that has passed through the sample 11.

Since the detection plate 8 is a plate made of a light element metal such as aluminum or beryllium, the backscattered electron image generated when the sample 11 is scanned with the narrowly focused electron beam 9 is reflected on the detection plate 8.
is detected and amplified and displayed on the observation device 20. In addition, to switch to the observation mode of the transmitted sample image, the mode changeover switch of the observation device 20 is switched to stop the backscattered electron detection device, and the fluorescent light 1 plate installed at the bottom of the barrel 3 of the electron microscope body is set. Create a transmission sample image. At this time, a large amount of backscattered electrons collide with the detection plate 8, but since the electrical system of the backscattered electron detection device is cut off and does not operate, it will not be damaged.

In a conventional backscattered electron detection device using a semiconductor detection element, it was necessary to remove the semiconductor detection element from the electron beam path when switching modes, but in this embodiment, the detection plate 8 can remain fixed regardless of the mode change. . Therefore, a mechanism for moving the detection member is not required, and manufacturing costs can be significantly reduced.

Further, since there is no need to move the detection member when switching modes, the operation is simplified, and since the detection plate 8 is a single aluminum plate, it can be used semi-permanently. As a result, an advantage can be obtained that it can be provided at about 1/100th the price of a conventional single reflector tube detector.

By installing the backscattered electron detection device of this embodiment close to a light metal plate such as aluminum above the sample, it can be constructed at an extremely low cost and has advantages such as easy operation.

FIG. 2 is an explanatory diagram of a backscattered electron detection device according to another embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. In this case, the aperture plate 7 and the detection plate 8 are connected to the tube 23 by the pole pieces 10a, 10bK of the objective lens.

In this way, the O-ring 2 and cylinder body 3 used in the apparatus shown in FIG. 1 are not needed, and the structure is advantageously simplified.

FIG. 3 is a cross-sectional view of a main part of a backscattered electron detection device according to still another embodiment of the present invention. It is wound around the stand 24 and pulled out.

That is, in the case of the apparatuses shown in FIGS. 1 and 2, the sample 11 was supported separately on a sample support stand 24 (not shown), but in this case, there is an advantage that the sample support stand 24 can be shared and simplified. can get.

Although the detection plate 8 of the above-mentioned embodiments uses an aluminum plate, a light material such as beryllium or carbon may be processed into a plate shape and used instead of aluminum.

Claims (1)

[Claims] 1. In a backscattered electron detection device such as an electron microscope, which has a backscattered electron detection element that is installed around an electron beam path to face the surface of a sample and detects backscattered electrons reflected from the sample, A backscattered electron detection device characterized in that the backscattered electron detection element is constructed using a detection plate made of a light element material. 2. The backscattered electron detection device according to claim 1, wherein the light element member is any one of aluminum, beryllium, and carbon.