JPH03274528A - Auger electron spectroscopic device - Google Patents

Abstract

PURPOSE:To allow the Auger analysis of microparts with <=50nm diameter of an electron beam by providing an electron gun of an electric field release type, a double focusing optical system of the electron beam, a hemispherical electrostatic analyzer, and a position sensitive detector in the electron spectroscopic device which analyzes the elements contained in a sample. CONSTITUTION:The electron beam 2 generated from the electron gun 1 of the electric field radiation type is focused by the double focusing optical system consisting of two pieces of magnetostatic lenses 3,4 and is deflected by a deflecting electrode 5 so that the sample 6 is irradiated with this beam. The Auger electrons 7 generated from the elements contained in the sample 6 are focused by an electrostatic lens 10 and are subjected to an energy analysis by the hemispherical electrostatic analyzer 9. These electrons are detected by the position sensitive detector 10. The current quantity of the electron beam is greatly improved in the microdiameter of the beam by combining the electric field radiation type electron gun 1 and the double focusing optical system in such a manner. The element distribution analysis in the microregion of <=50nm is possible in this way and this device is effective for the research and development of semiconductor materials, superconducting materials, etc., and for the foreign matter analysis of microparts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an Auger electron spectrometer that analyzes elements in minute portions on the surface of a sample.

[Conventional technology]

In an Auger electron spectrometer, a sample is irradiated with an electron beam, Auger electrons generated from the sample surface are detected, and the composition of the sample surface is analyzed. By focusing the electron beam, it is possible to measure the elemental distribution in a microscopic area. A conventional Auger electron spectrometer is shown in FIG.

The electron beam 22 generated by the electron gun 21 is transmitted to the electron optical system 2.
3. After passing through the deflection electrode 24, the sample 25 is irradiated. Auger electrons 26 generated from the surface of the sample 25 by irradiation are energy analyzed by an electrostatic analyzer 27 and detected by an electron multiplier 28 (Shiki and Yoshi ml: Auger electron spectroscopy for users (Kyoritsu Shuppan) ) 1989 PP32-59).

In general, in an Auger electron spectrometer, the intensity of the Auger electrons obtained is weak compared to the background electron intensity. The background component is removed by differentiating the signal intensity distribution with respect to energy. The differential calculation described above is performed in the measurement system 29 by an electronic circuit or a computer.

[Problem to be solved by the invention]

The conventional technique described above has a problem in that it is difficult to analyze extremely small parts of 50 nm or less.1 The size of the minimum area that can be analyzed depends on the diameter of the electron beam 22. In conventional devices, the practical electron beam diameter was limited to 50 nm. This is because a thermal radiation type emitter is used as the electron gun 21. FIG. 6 shows the dependence of the electron beam diameter on the electron beam current measured with the conventional device 1.

The electron beam diameter strongly depends not only on the amount of electron beam current but also on the acceleration energy of the electrons, but even with an electron beam with an energy of 20 keV, which yields the smallest beam diameter, the amount of current that can be obtained with a beam diameter of 50 nm or less is was less than 0°5 nA, and it was not possible to obtain the sensitivity necessary for measuring Auger electrons. Further, even in analysis using a beam system of about 100 nm, the beam current amount is small and the obtained Auger electron intensity is very weak, so it is necessary to increase the measurement time and integrate the signal intensity.

For this reason, the voltage running speed of the electrostatic analyzer must be slowed down, and it takes time to measure the energy spectrum, and it takes an enormous amount of time to measure the two-dimensional elemental distribution (mapping) on the sample surface. Ta.

For example, 10μm×10μm with a beam diameter of 100nrn
In order to map the area, it is necessary to measure the energy spectrum at 100 x 100 points, and if it takes 0.5 seconds to measure one point, approximately 83 minutes of measurement time is required for all points.

During this time, if the sample position drifts, it becomes impossible to obtain accurate elemental distribution.

SUMMARY OF THE INVENTION An object of the present invention is to obtain an Auger electron spectrometer capable of performing Auger analysis of minute parts with an electron beam diameter of 50 nm or less.

[Means to solve the problem]

The above purpose is to use a field emission type electron gun in an Auger electron spectrometer that analyzes the elements contained in the sample by irradiating the sample with a focused electron beam and detecting the Auger electrons generated from the sample surface. This is achieved by equipping the electron beam with dual focusing optics, a hemispherical electrostatic analyzer and a position sensitive detector.

[Effect]

This device focuses the electron beam with a double focusing optical system consisting of two magnetostatic lenses, and then deflects it with a deflection electrode to irradiate the sample. Therefore, the amount of electron beam current can be significantly increased even if the beam diameter is small. improves. Furthermore, Auger electrons incident on the hemispherical electrostatic analyzer undergo dispersion according to their energy in the electric field in the analyzer, and reach the position-sensitive detector in a spread manner. By detecting these at once with the above detector, it is possible to
The energy spectrum near the Auger electron peak can be measured instantly. Note that when performing single-element mapping, a differential spectrum can be obtained by scanning a sample with an electron beam, measuring an energy spectrum near the peak energy at each scanning point, and using a computer.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram explaining the first embodiment of the Auger electron spectrometer according to the present invention, FIG. 2 is a diagram showing the relationship between the diameter of the electron beam and the amount of current in the above embodiment, and FIG. 4 is a diagram showing a spectrum, (a) is a diagram showing a spectrum near the energy peak, (b) is a diagram showing a differential spectrum, and FIG. 4 is a diagram explaining a second embodiment of the Auger electron spectrometer according to the present invention. be.

First Embodiment In FIG. 1 for explaining the first embodiment, 1 is a field emission type electron gun, 2 is an electron beam, 3 and 4 are magnetostatic lenses, and 5
6 is a deflection electrode, 6 is a sample, 7 is an Auger electron, 8 is an electrostatic lens, 9 is a hemispherical electrostatic analyzer, 10 is a position sensitive detector, 11 is a buffer memory, and 12 is a computer. Next, a method for analyzing microscopic parts using an Auger electron spectrometer will be explained.

The electron beam 2 generated from the field emission type electron gun 1 is 2
The sample 6 is focused by a double focusing optical system consisting of magnetostatic lenses 3 and 4 and deflected by a deflection electrode 5.
irradiate. Thereby, the Auger electrons 7 generated from the elements contained in the sample 6 are focused by the electrostatic lens 8, subjected to energy analysis by the hemispherical electrostatic analyzer 9, and detected by the position sensitive detector 10. By combining the field emission type electron gun 1 and the double focusing optical system, the amount of electron beam current was significantly improved even at a small beam diameter.

FIG. 2 shows the relationship between the diameter of the electron beam and the amount of current in this example. The extraction voltage of the electron beam is approximately 4kV,
Take an emission current of 100 μA and increase the accelerating voltage to 20 μA.
When set to kV, at a beam diameter of 50 nm, the current amount is approximately 10 nA, and even at a minimum beam diameter of 10 nm, the current amount is approximately 10 nA.
A current amount of nA was obtained. Compared to the conventional example shown in FIG. 5, this is about 30 times, 1
At 0 nm, the improvement is about 50 times.

Next, a method for detecting Auger electrons will be explained. First, the voltage of the hemispherical electrostatic analyzer 9 is set to a value that allows Auger electrons (energy Eo) of the target element to pass through. Auger electrons incident on the entrance of the hemispherical electrostatic analyzer 9 undergo dispersion according to their energy in the electric field in the analyzer.

In other words, Auger electrons with higher energy than Eo have less change in their orbits due to the electric field, so the A of the position sensitive detector 10
Auger electrons with lower energy than the EO undergo a larger trajectory change and reach the B side of the detector. By detecting the Auger electrons that have undergone the above energy dispersion at once with the position sensitive detector 10, the voltage of the hemispherical electrostatic analyzer 9 can be detected as shown in FIG.
) can instantly measure the energy spectrum near the Auger electron peak. The energy width that can be detected at one time by the hemispherical electrostatic analyzer 9 of this embodiment is 25 eV.

When performing element mapping, sample 6 is
, and at each scanning point, the peak energy (
Measure the energy spectrum near Ep). The energy spectrum at each measurement point is transferred to the computer 12 via the buffer memory 11, and then subjected to differential calculation.
A differential spectrum as shown in FIG. 3(b) is obtained.

Since the present invention does not require time for energy travel to measure differential spectra, element mapping can be performed at high speed. For example, considering mapping of 128 x 128 points, if it took 0.1 seconds to obtain the energy spectrum of one measurement point using the conventional method using energy tracing, in the present invention, it takes 0.1 seconds x 128 x 128 (71 hours) to obtain the energy spectrum of one measurement point. , which means a saving of about 26 minutes.

Second Embodiment FIG. 4 is a diagram illustrating an Auger electron spectrometer in a second embodiment of the present invention, in which 13 is a diffracted electron beam, 14
is a fluorescent screen, 15 is a reflection or diffraction spot, 1
6 is a detector. In this embodiment, while scanning the surface of the sample 6 with the electron beam 2, Auger electrons 7 are detected as in the first embodiment, and the electron beam 13 diffracted from the surface of the sample 6 is applied to the fluorescent screen 14. , the intensity of the spot 15 generated on the fluorescent screen 14 is detected by the detector 1.
Since the zero-diffraction electron beam 13 measured in step 6 sensitively reflects the crystalline state of the surface of the sample 6, it is possible to measure the crystallinity distribution in minute parts at the same time as analyzing the elemental distribution by detecting Auger electrons 7 on the sample surface. I can do it.

〔Effect of the invention〕

As described above, the Auger electron spectrometer according to the present invention irradiates a sample with a focused electron beam, detects Auger electrons generated from the sample surface, and analyzes elements contained in the sample. By having a field emission type electron gun, a double focusing optical system for the electron beam, a hemispherical electrostatic analyzer, and a position sensitive detector,
Element distribution analysis in a micro region of 50 nm or less, which has been difficult in the past, becomes possible, and it can bring great effects to the research and development of semiconductor materials, superconducting materials, etc., and to the analysis of foreign substances in micro parts.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the first embodiment of the Auger electron spectrometer according to the present invention, FIG. 2 is a diagram showing the relationship between the diameter of the electron beam and the amount of current in the above embodiment, and FIG. 4 is a diagram showing spectra, (a) is a diagram showing a spectrum near the energy peak, (b) is a diagram showing a differential spectrum, and FIG. 4 is a diagram illustrating a second embodiment of the Auger electron spectrometer according to the present invention. FIG. 5 is a diagram showing a conventional Auger electron spectrometer, and FIG. 6 is a diagram showing the electron beam current dependence of the electron beam diameter measured by the conventional device. 1... Field emission electron gun 2... Electron beam 3.4... Double focusing optical system 6... Sample 7... Auger electron 9... Hemispherical electrostatic analyzer 10... position sensitive detector

Claims (1)

[Claims] 1. In an Auger electron spectrometer that irradiates a sample with a focused electron beam, detects Auger electrons generated from the sample surface, and analyzes the elements contained in the sample, a field emission type electron gun and an electron beam are used. An Auger electron spectroscopy device characterized in that it is equipped with a dual focusing optical system, a hemispherical electrostatic analyzer, and a position sensitive detector.