JPH05129000A - Ion gun for recti-collision ion scattering spectroscopic use - Google Patents

Abstract

PURPOSE:To provide an ion gun for recti-collision ion scattering spectroscopic use able to make the scattering angle to 180 degree and the impact coefficient to zero, and to improve analytic accuracy. CONSTITUTION:An electromagnet 7 is provided along an ion channel to bend trajectories of ions emitted from an ion source 6. Trajectories 17 of ions scattered from an analysis sample 15 at a scattering angle of 180 degree are drawn and bended, and the ions are introduced in an energy analyser 8, wherein intensity of scattered ions and moreover emitted positions of ions are measured by a position detector 14 so that energy analysis can be carried out. The central axes of respective components are made to lie on a same plane, hence the scattering angle can be made to 180 degree and the impact coefficient can be made to zero so as to improve the position analysis accuracy of atoms constructing the sample surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a physical analysis of a solid surface,
The present invention mainly relates to a novel ion bombardment for direct collision ion scattering spectroscopy for performing accurate analysis of direct collision ion scattering effective for atomic structure analysis of a solid surface.

[0002]

2. Description of the Related Art In the direct collision ion scattering spectroscopy, a solid sample is irradiated with an ion beam having a constant energy in an ultrahigh vacuum chamber, and the energy of the scattered ions at a scattering angle of about 160 degrees is analyzed. It is a means for analyzing the atomic structure of the surface of the solid sample. Figure 3
It is explanatory drawing which shows the structural example of a conventional apparatus, and in order to analyze using this apparatus, the analysis sample 2 to be analyzed is irradiated with the ion beam whose energy is constant from the ion gun 1. The scattered ions are subjected to energy analysis in the energy analyzer 4 of the electrostatic energy analyzer 3 and detected by the secondary electron multiplier (channel tron) 5. The pulsed signal thus output is first amplified by a preamplifier and then filtered to remove noise such as high frequencies. Next, after being amplified again by the pulse amplifier, the scattered ion intensity is obtained by counting the pulse signals with the pulse counter, and the data is taken into the computer through the interface. The electrostatic energy analyzer 4 is operated by being controlled by a computer through an interface and an analyzer controller. Here, in the conventional device, it is impossible to dispose the ion gun 1 and the electrostatic energy analyzer 4 at the same place due to the geometrical structure, and therefore, in the conventional device, the scattering angle is 160 degrees. According to the degree, this is approximately referred to as direct collision ion scattering spectroscopy for analysis.

[0003]

However, when the scattering angle is set to about 160 degrees in this way, especially when the analysis sample is a compound, when incident ions collide with atoms constituting the analysis sample, Since the collision coefficient (impact parameter) scattered at that angle differs depending on the type of atom, there is a problem in that the position analysis accuracy of the atoms constituting the sample surface is not very good.

The present invention provides an ion gun which can eliminate the influence of the scattering angle of 180 degrees and the collision coefficient of zero to improve the analysis accuracy in the direct collision ion scattering spectrometer. It is intended.

[0005]

[Means for Solving the Problems] The present inventors have conducted diligent research to solve the above problems and achieve the above objects,
To complete the present invention by finding that the ion beam can be bent at a constant angle and the scattering angle can be set to 180 degrees by providing an electromagnet in the course of the ion beam emitted from the ion source to achieve the purpose. I arrived. That is, the present invention is directed to an ion source, an electromagnet for bending an ion orbit having a constant acceleration energy and a constant direction emitted by the ion source at a constant angle, and the same orbit of the emitted ions in the opposite direction. This is an ion gun for direct collision ion scattering spectroscopy, which is provided with a means for analyzing and detecting the energy of incident ions by the magnetic field of an electromagnet.

Each of the parts constituting the present invention may be a combination of conventionally used ones. As an electromagnet for forming a magnetic field, for example, a 20 cm × 20 cm area of the part corresponding to the passage of the ion beam is 1000. ~ 700
It is preferable that the magnetic field can be set so that the magnetic field is about 0 [A / m].

[0007]

Since the ion gun of the present invention is constructed in this way, when the ion beam emitted from the ion source passes through the uniform magnetic field of the electromagnet, the Lorentz force acting on the ion beam causes Fleming's left hand to act. The orbit is bent in the direction according to the law as an orbit 16 as shown in FIG. Next, this ion beam collides with the atoms constituting the analysis sample, and the ions scattered at a scattering angle of 180 degrees enter the ion gun from the ion irradiation port of the ion gun, pass through the magnetic field of the electromagnet, and pass through the analysis sample. The direction of the scattered ion is different from that of the ion beam irradiated to the analysis sample because the Lorentz force acts in a direction different from that of the ion beam irradiated to the analysis sample. Draw 17. Further, since the orbits of the scattered ions at this time are different when the respective energies are different, the position detector (PSD) 14 measures the scattered ion intensity as well as the position where this ion is detected. The energy analysis becomes possible.

[0008]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing in cross section one embodiment of the ion of the present invention, and FIG. 2 is a perspective view showing one embodiment of the ion gun of the present invention.

The ion gun of the present invention mainly comprises an ion source 6, an electromagnet 7 for bending the trajectory of an ion beam, an energy analysis section 8 by a magnetic field, and the like. Then, these central axes are in the same plane, and the ion source 6 and the energy analysis unit 8 are arranged to extend symmetrically with respect to the central axis of the ejection portion.

Next, each component will be described. The ion source 6 is of the electron impact type and is composed of the following parts. That is, by passing a current through the filament 9, the cathode 10 in contact with it
Are heated and an electric potential is applied between the cathode 10 and the anode 11, thereby accelerating the electrons emitted from the cathode 10 to several tens eV, and with this energy, collision ionization with the gas (He gas) supplied here Is performed to generate ions, and the generated ions are accelerated and emitted. Next, the electromagnet 7 is an ordinary electromagnet, is provided in a portion corresponding to the passage of the ion beam, bends the trajectory of the ion beam, and the ion beam passing through this magnetic field passes through the electrostatic lens 13 and the polarizing plate 12 to analyze the sample. It is designed to converge on 15 surfaces. Furthermore, the energy analysis unit 8
Can be an ordinary electrostatic energy analyzer, and ions that are bent by a magnetic field and ejected from the ejection part 18 and hit the analysis sample 15 and scattered at a scattering angle of 180 degrees pass through the ejection part 18 and are generated in the magnetic field. As described above, the energy is analyzed by the position detector 14 when the energy reaches the energy analysis unit 18, and the orbits of the scattered ions are also displaced when the energy of each scattered ion is different, so that the position at which the ions are emitted is also measured. It has become.

In this ion gun 6, for example, irradiation ions are He ⁺ ions of 1 KeV, and a region of 20 cm × 20 cm where the electromagnet 7 hits the passage of the ion beam has a magnetic field of about 2330 [A / m]. If the energy analyzer 8 is set to 400 eV to 1K,
It becomes possible to analyze He ⁺ scattered ions of eV, and it is possible to make the analysis accuracy of the atomic position of 0.01 angstrom or less even for a compound such as InP.

[0013]

According to the present invention, the orbit of emitted ions can be bent by the electromagnet, so that the central axes of the respective components can be in the same plane, and the scattering angle can be 180 degrees.
When the incident sample collides with the atoms that make up the analytical sample, the collision coefficient that scatters at that angle is different when the incident ion collides with the atom that constitutes the analytical sample. It is possible to improve the accuracy of position analysis of the atoms constituting the surface, and a remarkable effect is recognized.

[Brief description of drawings]

FIG. 1 is an explanatory view showing in cross section one embodiment of an ion gun for direct collision ion scattering spectroscopy of the present invention.

FIG. 2 is a perspective view showing an embodiment of an ion gun for direct collision ion scattering spectroscopy of the present invention.

FIG. 3 is an explanatory diagram showing an example of a conventional direct collision ion scattering spectrometer.

[Explanation of symbols]

 6 Ion source 7 Electromagnet 8 Energy analysis section 15 Analytical sample 16 Ejection ion orbit 17 Incident ion orbit

Claims (1)

[Claims] 1. An ion source, an electromagnet for bending an orbit of an ion having a constant acceleration energy and a constant direction emitted from the ion source at a constant angle, and the same orbit of the emitted ion is incident in the opposite direction. An ion gun for direct collision ion scattering spectroscopy, comprising: means for analyzing and detecting the energy of the generated ions by the magnetic field of an electromagnet.