JPS6326925Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron probe device, and particularly to an electron probe device that can obtain a reflected electron beam image with good spatial resolution.

When a sample is irradiated with a narrowly focused electron beam, the electrons incident on the sample undergo repeated elastic scattering and inelastic scattering, and some escape from the sample as backscattered electrons (backscattered electrons). Among the backscattered electrons, those that collide with sample atoms many times escape to the outside of the sample from the sample position away from the incident point of the irradiated electron beam, and therefore, these electrons have a negative effect on the spatial resolution of the backscattered electron beam image. give.

This invention was made in view of the above points,
It takes advantage of the fact that the energy of reflected electrons is lost depending on the number of collisions with sample atoms, and the electron beam is used to analyze the sample by irradiating the sample with an electron beam and detecting the electrons from the sample. The probe device includes an energy dispersive electron detector for detecting reflected electrons from the sample, a deflection means for deflecting the reflected electrons and guiding them to the detector, and a combination of the deflection means and the detector. an X-ray shielding plate disposed between the detector and having an electron transmission hole; a pulse height analyzer to which the detection signal of the detector is guided to obtain a signal based on reflected electrons with a specific energy; and an X-ray shielding plate with an electron transmission hole; This is characterized in that a backscattered electron image of the sample is obtained using a signal based on .

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, an electron beam EB generated from an appropriate electron gun is narrowly focused onto a sample 2 by a converging lens 1. The electron beam EB is deflected by a deflection coil 4 to which a scanning signal is supplied from the scanning signal generating circuit 3, and as a result, the sample surface is scanned by the electron beam. A part of the electrons generated from the sample 2 by irradiating the sample 2 with the electron beam EB are deflected by the electrostatic deflection plate 5, and are transmitted through the opening 7 of the shielding plate 6 to a silicon semiconductor in which, for example, lithium is diffused. The beam enters an energy dispersive electron detector 8 consisting of:
The shielding plate 6 is made of an X-ray absorbing material such as lead, and is removably disposed in front of the detector 8. Although not shown, the detector 8 is cooled with liquid nitrogen. The detector 8 outputs a pulse having a height corresponding to the energy of each incident electron, and the pulse signal is supplied to a pulse height analyzer 9. The pulse signal of a specific height selected by the pulse height analyzer 9 is converted into an analog signal by a rate meter 10, and a display device 11 such as a cathode ray tube to which a scanning signal is supplied from the scanning signal generating circuit 3 is converted into an analog signal by a rate meter 10. supplied to

In the configuration as described above, the electron beam to the sample 2
Electrons are generated from the sample by EB irradiation, and the electrons have a wide energy distribution. FIG. 2 shows the energy distribution of this electron, and the peak P is based on reflected electrons that are elastically scattered by the incident electrons with atoms on the surface of the sample, and its energy is equal to the energy of the incident electrons.
Electrons with energy lower than the peak P are inelastically scattered inside the sample, and some of their energy is lost.The electrons that are scattered at a deeper position from the sample surface and escape to the outside of the sample have more energy. Big loss. Electrons having the energy distribution shown in FIG. 2 are deflected by a deflection plate 6 and detected by an energy dispersive detector 8, and a pulse signal having a height corresponding to the energy of the electrons is sent to a pulse height analyzer 9. supplied to Here, if the pulse height analyzer selects only pulse signals based on electrons with energy A shown in FIG. 2 and supplies them to the display device 11 via the rate meter 10, the display device displays a reflected electron beam image of the sample However, this image is based only on the backscattered electrons that are elastically scattered on the surface of the sample 2, and is based on the electrons that are inelastically scattered inside the sample and escape from the sample position away from the incident point of the irradiated electron beam. Since the base signal is removed, the spatial resolution is extremely good.

For example, the electron with energy B shown in Figure 2 is
These are reflected electrons that have reached a certain depth D from the sample surface and are inelastically scattered.If only the pulse signal based on the electrons with energy B is selected by the pulse height analyzer 9, the depth D of the sample 2 can be detected. It is possible to obtain a backscattered electron image based on a signal containing a large amount of information.

In the embodiment described above, the opening 7 is provided in the front surface of the detector 8.
A shielding plate 6 having a
This prevents X-rays from entering the detector and prevents the generation of noise signals due to X-rays. Furthermore, if the shielding plate 6 is removed from the front of the detector 8 and the X-rays from the sample are detected by the detector 8, X-ray analysis of the sample can also be performed.

The present invention has been described in detail above, and the present invention can significantly improve the spatial resolution of backscattered electron beam images, and furthermore, the backscattered electrons can be used to analyze the depth of the sample without the influence of X-ray noise. This can be done in the same condition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the energy distribution of reflected electrons from a sample. 1: Converging lens, 2: Sample, 3: Scanning signal generation circuit, 4: Deflection coil, 5: Electrostatic deflection plate, 6: Shielding plate, 7: Aperture, 8: Electron detector, 9: Wave height analyzer, 10 : Rate meter, 11: Display device.

Claims (1)

[Scope of utility model registration request] An electron probe device that analyzes a sample by irradiating the sample with an electron beam and detecting electrons from the sample includes an energy dispersive electron detector for detecting reflected electrons from the sample; Deflection means for deflecting reflected electrons and guiding them to the detector;
An X-ray shielding plate disposed between the deflection means and the detector and having an electron transmission hole, and a wave height analysis for guiding the detection signal of the detector and obtaining a signal based on reflected electrons of a specific energy. and an electron probe device configured to obtain a backscattered electron image of the sample using a signal based on the backscattered electrons of the specific energy.