JPS6212464B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for analyzing a sample by exciting a sample with a charged particle beam and analyzing a secondary particle beam emitted from the sample. Concerning improvements to the part that performs energy analysis of particle beams.

When a sample is bombarded with an electron beam or an ion beam, seed information about the sample can be obtained by performing energy analysis, mass spectrometry, etc. on the particle beam such as electrons and ions emitted from the sample. For example, when a sample is bombarded with an electron beam, atoms on the sample surface are excited and so-called Auger electrons are emitted. Measuring the energy of this Augier electron reveals the type of atom that emitted the Augier electron, and quantitatively detecting the Auger electron with a specific energy determines the density of the atom that emitted the Augier electron, that is, the content of a specific element on the sample surface. I understand.

FIG. 1 shows an example of a currently proposed comprehensive analytical device for performing the above-mentioned type of analysis. O is a source of electrons and ions, and either particle is emitted by switching. A is an accelerating electrode, L is an electron lens that focuses these charged particle beams onto the sample surface, and D is a deflection electrode that scans the sample surface with the particle beam.
S is a sample. The sample S is set at an angle so that the generated particle beam can easily enter the subsequent analysis section. 1 is the particle beam irradiation point on the sample S, 2 is the entrance slit of the energy analyzer 3, and l is an electron lens for focusing the image of the point 1 on the sample onto the slit 2. The energy analyzer 3 is a double hemispherical shell,
A voltage is applied between each hemisphere, and a voltage is formed between the hemispheres in the radial direction. Among the charged particles that entered this double spherical shell through slit 2, particles with a specific energy corresponding to the strength of the electric field travel in a group of trajectories whose center orbit is an arc passing through the middle of the double spherical shell. Particles that move along the spherical shell and have other energies that are concentrated on the exit slit 4 hit the spherical shell or collide at a point outside the exit slit 4. In this way, the energy analyzer 3 separates and extracts particles with a specific energy. The particle beam passing through the energy analyzer 3 and exiting from the exit slit 4 is focused again onto the entrance slit 11 of the mass spectrometer 5 by the lens ^l1 . The mass spectrometer 5 is a quadrapol type,
Only particles with a specific mass number go straight through the exit slit 6.
The particle beam can pass through the particle beam detector 7 and be detected. Reference numeral 14 denotes a particle beam detector placed laterally between the energy analyzer 3 and the mass spectrometer 5, and when only energy analysis is performed, the particle beam exiting the energy analyzer is detected by the repulsion electrode 12. It is detected by the detector 14 by bending it in the opposite direction.

The present invention enables the charged particle detectors 7 and 14 of each of the energy analyzer and the mass spectrometer to be shared by one detector 7 in the apparatus shown in FIG. The purpose of this invention is to eliminate the need for the lens ^l1 and the repulsion electrode 12. In this case, the exit slit 4 of the energy analyzer and the inlet slit 11 of the mass spectrometer
One slit will also be shared.

The present invention skillfully utilizes the properties of the Quadrupole mass spectrometer, which causes dispersion by mass number by applying a DC voltage and an alternating voltage to four parallel electrodes in a superimposed manner. However, when the DC voltage is removed, the charged particles move in a wavy manner, but they do not diverge and instead move in a straight line. The present invention will be explained below with reference to Examples.

FIG. 2 shows an embodiment of the present invention. The optical system of the charged particle beam that excites the sample is shown in a simplified manner. Also, parts corresponding to the configuration in FIG. 1 are given the same reference numerals. B is an excitation charged particle beam that irradiates the sample S, and 1 is the irradiation point. The energy analyzer 3 is a double spherical shell that is cut into the center of the hemisphere by θ (20° to 40°), and the tangent at the left end of the double spherical shell to the great circle that passes through the middle of this double spherical shell is Sample S
Passing through point 1 above, the right end surface of the double spherical shell is beam B
It is fixed so that the direction perpendicular to the double spherical shell, that is, the tangent at the right end of the spherical shell of the great circle passing through the middle of the double spherical shell, is parallel to the beam B. As is clear from the figure, if the great circle passing through the middle of the double spherical shell is extended as an arc on the left side, it will contact beam B, and the point of contact M will be located on the extension of the horizontal plane of the right end surface of the double spherical shell. It is a relationship. Since the point 1 on the sample S is a point source of the secondary particle beam, this point corresponds to the position of the entrance slit of the energy analyzer 3, even if no slit is used. Among the charged particles emitted from the point, those with a specific energy are an extension of the straight line connecting point 1 and the spherical center C of the double spherical shell of the energy analyzer, and a straight line that exits the energy analyzer 3 and extends vertically downward. They will converge at the intersection Q. The exit slit 4 of the energy analyzer 3 is located at the Q point, and this slit 4 also serves as the entrance slit of the subsequent quadrupole mass spectrometer 5. A quadrapol mass spectrometer consists of four parallel electrodes extending vertically, and a DC voltage of opposite polarity and a high-frequency alternating voltage are superimposed and applied to adjacent electrodes, and charged particles incident parallel to the electrodes are Among them, only particles with a specific mass number travel straight and particles with other masses diverge. 8 is an AC power supply that applies alternating voltage to the four electrodes of the quadrapol mass spectrometer, 9 is also a DC power supply, and switch 10
When the contact b side is set, alternating current and direct current are superimposed and applied to the mass spectrometer, and when the contact a side is set, only an alternating current voltage is applied. Reference numeral 6 represents an exit slit for taking out the particle beam that has come straight forward, and 7 represents a charged particle detector. If you eliminate the DC component of the voltage applied to the four electrodes in a quadrapol mass spectrometer and use only the AC component, the mass spectrometry function will disappear, but the slit 4
Charged particles having a tendency to diverge that have entered further can be made to travel substantially straight toward the exit slit 6 without being diverged. Therefore, when only energy analysis of charged particles is performed and mass spectrometry is not required, the detector 7 can be used as is by cutting off the DC component of the voltage applied to each electrode of the mass spectrometer 5.

Comparing the device of the present invention with the conventionally proposed device shown in FIG. By making it possible to add and subtract separately from the alternating current component, the same mass spectrometer can be used simply to make the incident beam go straight without causing it to diverge, and the lens and repulsion electrode between the energy analyzer and the mass spectrometer can be omitted. A single particle detector can be used in the energy analyzer and the mass spectrometer, and the configuration of the entire device can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of an analysis device that has already been proposed, and FIG. 2 is a longitudinal sectional side view of an embodiment of the device of the present invention. B...excitation ray beam, S...sample, 3...energy analyzer, 5...quadrapol mass spectrometer, 6...exit slit, 7...charged particle detector.

Claims (1)

[Claims] 1 In a type of analyzer that irradiates a sample with an excitation beam and analyzes the secondary particle beam emitted from the sample, the secondary particle beam analyzer is an energy analyzer, a quadrapol mass spectrometer, and a particle beam detector. The exit slit of the energy analyzer and the inlet slit of the mass spectrometer are shared by the same slit. A sample analysis device using a charged particle beam, characterized in that it is possible to select between applying only a charged particle beam.