JP2003021609A - Parallel magnetic field type rutherford back scattering analyzer, energy spectrum measuring method for scattered ion using it and crystal axis detecting method for sample using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To align a crystal axis and an ion beam by segregating scattered ions different in the number of convergences, easily measuring an energy spectrum in high resolution and detecting the crystal axis of a sample without labor and causing contamination in the sample in regard to a parallel magnetic field type Rutherford back scattering analyzer converging scattered ions back- scattered from a sample entered by the ion beam to a beam axis by a magnetic field parallel with the ion beam. SOLUTION: The scattered ions are segregated to improve penetration of scattered ions with a small angle of incidence by using a pair of cylindrical members arranged in parallel with the beam axis of the ion beam with a predetermined interval. By using a two-dimensional scattered ion detector 8, the energy spectrum is measured on the basis of a detection position of the scattered ions, the crystal axis of the sample is detected on the basis of a detection amount distribution of the scattered ions, and the crystal axis and the beam axis of the ion beam are aligned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel magnetic field type Rutherford backward for converging scattered ions backscattered by a sample into which an ion beam of high and medium energy is incident on a beam axis by using a magnetic field parallel to the ion beam. The present invention relates to a scattering analyzer.

[0002]

2. Description of the Related Art For example, in Japanese Unexamined Patent Publication No. 7-190963 (Gazette 1), scattered ions backscattered by a sample to which an ion beam of high and medium energy is incident are beamed by using a magnetic field parallel to the ion beam. A parallel-field, Rutherford backscattering analyzer focusing on an axis is described. FIG. 3 shows a schematic configuration of the Rutherford backscattering analyzer described in the above publication. As shown in Figure 3, 400k
The helium ion beam 2 emitted from the ion source 1 supplied with a high voltage of about V is accelerated by the voltage applied to the accelerating tube 3 while passing through the accelerating tube 3, and travels toward the sample 4. Scattering ions 5 elastically scattered on the surface of the sample 4
Is bent by a magnetic field parallel to the beam axis of the ion beam 2 generated by an electromagnet 6 composed of a solenoid coil 61 and a magnet yoke 62, and repeatedly comes into contact with (converges to) the beam axis while performing a spiral motion.
Draw a trajectory. An iris type slit 7 (aperture) is arranged so that the scattered ion 5 having a specific energy and a specific scattering angle passes through the ion beam 2 at a position where the scattered ion 5 converges on the beam axis. Only the scattered ions 5 having the energy of 1 are discriminated, and the scattered ions 5 diverging again are detected by the two-dimensional scattered ion detector 8 to obtain the energy spectrum. Sample 4 based on the energy spectrum thus obtained
It is possible to identify the component elements of and the composition analysis in the depth direction (ion channeling analysis). The scattered ion detector 8 may be, for example, a microchannel plate in which a large number of two-dimensional fine detection tubes are arranged.
A simplified appearance of the scattered ion detector 8 is shown in FIG.
As shown in FIG. 4, the scattered ion detector 8 has a small opening 81 at its center for passing the ion beam 2.
It has a donut shape. It is possible to measure the position of the scattered ions 5 that have passed through the slit 7 by means of fine detection tubes arranged in a two-dimensional array on the surface of the scattered ion detector 8. The scattered ions 5 of the same energy and the same energy scattered from the surface of the sample 4 are
After once converging at the position of the slit 7, it again diverges and enters the position at a distance R from the center of the detector. Since the scattered ions 5 having different energies converge at the position of the slit 7, the scattering angles are different. Therefore, the energy can be determined by the distance R. At this time, the magnetic field strength is changed for each energy of the scattered ion 5 to be measured, or the magnetic field strength is kept constant, and the distance between the sample 4 and the scattered ion detector 8 or the slit 7 is changed to The scattered ions 5 detected by the detector 8, that is, the scattered ions 5 passing through the slit 7 are selected for each energy, and the energy spectrum of the scattered ions 5 is measured.

On the other hand, in the channeling measurement of scattered ions 5 by the Rutherford backscattering analyzer, the crystal axis of the sample 4 is detected before the measurement and the axes are aligned so that the crystal axis and the beam axis of the ion beam 2 coincide with each other. There is a need. Conventionally, as a method of detecting the crystal axis of the sample 4, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 346412 (Gazette 2), X
A method of detecting the crystal axis of the sample 4 by using line reflection, and as shown in the prior art in paragraphs 0006 to 0007 of the publication 2, the scattered ions 5 are detected at each rotational position while rotating the sample 4. Then, there is a method of detecting the crystal axis of the sample 4 based on the detected amount of the scattered ions 5 detected.

[0004]

However, in the configuration as shown in FIG. 3, scattered ions 51, 52, 53, 54, ... Having different numbers of convergence pass through the slit 7 as shown in FIG. . Note that reference numeral 51 indicates that the number of convergences is 1
The number 52 of scattered ion trajectories, the number 52 of scattered ion trajectories with two convergence times, the number 53 of scattered ion trajectories with three convergence times, and the number 54 of scattered ion trajectories with four convergence times. Represents each orbit. Of course, there are scattered ions whose number of convergence is 5 or more, but they are not shown in FIG.
The arrow B indicates the direction of the magnetic field. When the scattered ions having different convergence times pass through the slit 7, the scattered ions having different energies are incident on the scattered ion detector 8. For example, as shown in FIG. 6, on the concentric circle of 75 mm from the center of the scattered ion detector 8, in the scattered ions 51, 52, 53, 54, the ions of scattered energy 400, 100, 50, 30 keV are incident. It became difficult to analyze the energy.

Further, in the method of measuring the energy spectrum of the scattered ions 5 by changing the magnetic field strength and the positional relationship among the sample 4, the scattered ion detector 8 and the slit 7, the stability after the magnetic field strength is changed is obtained. However, there is a problem in that it takes time and effort to position and position the sample 4 and the like.
Further, there is a problem that it is difficult to measure the energy spectrum of the scattered ions 5 with high resolution due to the restriction of the accuracy of changing the magnetic field strength and the positioning accuracy of the sample 4. For example, when the scattered ions 5 are He ⁺ ions, the distance L from the surface of the sample 4 to the position where the He ⁺ ions contact the beam axis (z axis) (that is, the distance between the sample 4 and the slit 7) is It is represented by the equation (a1).

[Equation 1] Where m is the mass of the scattered ions 5, qe is the charge of the scattered ions, ω _c is the cyclotron frequency, v is the ion velocity, and θ
Represents the scattering angle of the scattered ions 5, E represents the energy of the scattered ions 5, and B represents the magnetic field strength (the same applies hereinafter). Here, with respect to He ⁺ ions having the same scattering angle, in order to select ions of 300 keV and ions of 299 keV (energy resolution ΔE / E = 0.3%), for example, energy at a magnetic field strength B of about 2 Tesla is used. When detecting the spectrum, the required amount of change in the magnetic field strength B is only 33.4 gau.
It is as small as ss (= 2−2 × √ (299/300) [Tesla]), and it is difficult to stably control such a minute change in the magnetic field strength B. When the distance between the sample 4, the slit 7, and the scattered ion detector 8 is changed, the following equation (a2) is used.

[Equation 2] However, t is an elapsed time from when the scattered ions 5 are scattered on the surface of the sample 4 until they reach the scattered ion detector 8, x,
y and z are coordinates (that is, the position where the scattered ion 5 reaches the scattered ion detector 8) with the beam axis as the z axis (ie,
z = L), r is the scattered ion 5 is the scattered ion detector 8
It represents the distance from the z-axis (beam axis) of the position reached above (the same applies hereinafter). Here, assuming that the scattered ion detector 8 is annular as shown in the publication 1 and r is constant, the time t is expressed by the following equation (a3).

[Equation 3] By substituting this equation (a3) into the equation of z in the equation (a2), the following equation (a4) is derived.

[Equation 4] Further, since the scattered ions are in contact with the z axis (beam axis O) at the position of the slit 7, if the time until the scattered ions reach the scattered ion detector 8 after passing through the slit 7 is t1. , L = vcos θ · t1. Substituting this into the expression r in expression (a2) leads to expression (a5) below.

[Equation 5] Here, L∝v, and if the distance L is changed, the v of the scattered ions converged at the distance L also differs, so the distance 1 between the slit 7 and the scattered ion detector 8 must also be changed. I understand. For example, the same scattering angle 4
For He ⁺ ions of 5 °, in order to select 300 keV ions and 299 keV ions, L was set to 0.
It is necessary to change it by 584 mm, but the change amount of l at that time is as small as 0.145 mm. Further distance L,
The amount of change in l depends on the velocity v of the scattered ions 5 (L for selecting 299 keV and 298 keV,
The amount of change in l is 0.594 mm and 0.173 m, respectively.
m), it is difficult to stably control this minute distance.

Further, the crystal axis detecting method of the sample disclosed in the above-mentioned publication 2 requires an X-ray source and an X-ray detector, and
It is necessary to change the installation positions of the X-ray source and the X-ray detector depending on the crystal orientation, which causes a problem that the device becomes large and the cost becomes high. In addition, when measuring the crystal axis, it is necessary to adjust the axis while monitoring the X-ray, and there is a problem that this axis alignment takes time. Further, in the method disclosed in the publication 2 as the prior art, as shown in the publication 2,
There is a problem that it takes a lot of time to detect scattered ions while rotating the sample by 360 °, and that the sample surface is contaminated by constantly irradiating the ion beam during the scattered ion detection work for axis alignment. It was

Therefore, in order to solve the problems in the prior art, the present invention improves the parallel magnetic field type Rutherford backscattering analyzer so that the ion beam is parallel to the sample and the slit for energy discrimination. A movable plate-shaped slit having a plate shape, which is arranged so as to be movable and has an opening for passing an ion beam incident on the sample from the scattered ion detector side, and the slit between the sample and the movable plate slit. The number of convergences is increased by providing a movable cylindrical slit having a cylindrical shape, which is arranged so as to be movable in parallel with the ion beam and has an opening through which the ion beam incident on the sample from the scattered ion detector side passes. Discriminating scattered ions of different wavelengths, performing appropriate energy analysis, and easily performing high-resolution energy spectrum measurement, and Parallel magnetic field type Rutherford backscattering analyzer capable of detecting the crystal axis of the sample and aligning the crystal axis with the ion beam without causing contamination of the sample and the crystal axis of the sample in the apparatus It is intended to provide a detection method.

[0008]

In order to achieve the above object, the present invention provides a scattered ion detector for detecting scattered ions backscattered by a sample on which an ion beam is incident, and the ion beam. A magnetic field generating means for generating a magnetic field parallel to at least the sample from the sample to the scattered ion detector, and disposed between the sample and the scattered ion detector at a predetermined position with respect to the scattered ion detector. , The ion beam incident on the sample from the scattered ion detector side is passed, and the scattered ion having a specific energy and a scattering angle converged on the beam axis of the ion beam by the magnetic field of the magnetic field generation means is A parallel magnetic field type Rutherford rear having a plate-shaped discrimination slit having an opening for passing to the scattered ion detector side In the turbulence analyzer, an opening is provided between the sample and the discrimination slit so as to be movable in parallel with the ion beam, and has an opening for passing an ion beam incident on the sample from the scattered ion detector side. Plate-shaped movable plate-shaped slit, and an ion beam which is arranged between the sample and the movable plate-shaped slit so as to be movable parallel to the ion beam, and which is incident on the sample from the scattered ion detector side. It is configured as a parallel magnetic field type Rutherford backscattering analysis device, characterized in that it comprises a cylindrical movable cylindrical slit having an opening for passing through. In this invention, a plate-shaped movable plate-shaped slit having an opening for passing an ion beam incident on the sample from the scattered ion detector side is moved in parallel with the ion beam between the sample and the discrimination slit. A movable cylindrical slit having an opening for passing an ion beam incident on the sample from the scattered ion detector side, the ion beam being interposed between the sample and the movable plate slit. It is arranged so that it can move in parallel with.
If the positional relationship between the movable plate-shaped slit and the movable cylindrical slit is appropriately set, the scattered ions with the number of convergence times other than the specific number of times of the scattered ions that pass through the discrimination slit are moved by the movable member. It can be applied to the plate-shaped slit or the movable cylindrical slit to prevent the movable plate-shaped slit from reaching the scattered ion detector side.
For this reason, it becomes possible to preferably perform energy analysis. In the parallel magnetic field type Rutherford backscattering analyzer, the axial length Ls of the movable cylindrical slit is, for example, 1 / 6L <Ls <1 / 3L with respect to the distance L between the discrimination slit and the sample. Are established to satisfy the relationship. Further, if the scattered ion detector is a two-dimensional ion detector, that is, if it can detect the detection position of the scattered ions on the detection surface of the scattered ion detector, the scattered ion detector It is also conceivable that the apparatus is provided with an energy spectrum measuring means for measuring the energy spectrum of the scattered ions based on the detected position of the scattered ions detected. Accordingly, the scattered ions having different detection positions (specifically, the distance from the beam axis of the ion beam) can be simultaneously detected for each of the possessed energies, so that the magnetic field generation means can be set for each energy of the scattered ions to be measured. Magnetic field strength and the sample,
It is not necessary to change the distance between the discrimination slit and the scattered ion detector, and the energy spectrum of the scattered ions can be measured by one measurement. As the two-dimensional ion detector, for example, a microchannel plate in which a plurality of fine detection tubes are arranged in a two-dimensional manner, a plurality of one-dimensional (linear) ion detectors in an arrangement, and the like can be considered.

Further, a scattered ion detector for detecting scattered ions backscattered by the sample into which the ion beam is incident, and a magnetic field parallel to the ion beam are generated at least from the sample to the scattered ion detector. The ion beam that is disposed at a predetermined position with respect to the scattered ion detector between the magnetic field generation means and the sample and the scattered ion detector, and that is incident on the sample from the scattered ion detector side A plate-like plate having an opening for passing the scattered ions having a specific energy and a scattering angle converged to the beam axis of the ion beam by the magnetic field of the magnetic field generating means to the scattered ion detector side. A parallel magnetic field type Rutherford backscattering analyzer comprising a discrimination slit, wherein the scattered ion detector is 2 Also conceivable that it is configured as a parallel magnetic field type Rutherford backscattering analysis apparatus which is a source of an ion detector. As a result, as described above, since the scattered ions whose detection positions are different depending on the possessed energy can be simultaneously detected, the energy of the scattered ions is detected based on the detected position of the scattered ions detected by the scattered ion detector. If the energy spectrum measuring means for measuring the spectrum is provided, it is possible to measure the energy spectrum of the scattered ions with one measurement.

It is also conceivable that the apparatus further comprises crystal axis detecting means for detecting the crystal axis of the sample based on the detected amount distribution of scattered ions detected by the scattered ion detector. In this case, the crystal axis detecting means detects a plurality of belt-like low detection amount regions formed in a portion where the detection amount of the scattered ions is relatively low, and the crystal of the sample is detected based on the low detection amount regions. It is conceivable to detect the axis, and the crystal axis detecting means further comprises a center position of a portion where the plurality of low detection amount regions intersect with each other and a beam axis of the ion beam passing through the scattered ion detector. It is conceivable to detect the crystal axis of the sample based on the deviation. This is because the detection amount of the scattered ions scattered in the direction along the crystal plane of the sample is relatively low due to the so-called blocking phenomenon in which the scattering of ions is blocked by the constituent atoms of the sample, and thus the scattered ions From the detection amount distribution of (1), the directions of the plurality of crystal planes and the crystal axes that are the axes intersecting the crystal planes are detected (specified). As a result, the crystal axis of the sample can be detected by detecting the scattered ions once without using an X-ray source or the like. Further, if an incident angle adjusting means for adjusting the angle at which the beam axis of the ion beam is incident on the sample based on the detection result of the crystal axis detecting means is provided, the beam axis coincides with the crystal axis of the sample. It becomes possible. Further, the present invention is
Even if it is considered as a method for measuring an energy spectrum of scattered ions using the parallel magnetic field type Rutherford backscattering analyzer having the scattered ion detector which is a two-dimensional ion detector, or a method for detecting a crystal axis of a sample. Good.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments are specific examples of the present invention and are not of the nature to limit the technical scope of the present invention. FIG. 1 is a diagram for explaining a main part of a parallel magnetic field type Rutherford backscattering analyzer according to the embodiment of the present invention. The basic configuration of the parallel magnetic field type Rutherford backscattering analysis apparatus according to the embodiment of the present invention is the same as that of the conventional parallel magnetic field type Rutherford backscattering analysis apparatus.
FIG. 1 shows an ion beam 2, a sample 4, and an electromagnet (a concrete example of a magnetic field generating means) 6, an iris type slit (of a discrimination slit) similar to the conventional parallel magnetic field type Rutherford backscattering analyzer. (Specific example) 7 and a scattered ion detector 8 and a characteristic configuration of a parallel magnetic field type Rutherford backscattering analyzer according to the embodiment of the present invention. The scattered ion detector 8 is for detecting scattered ions backscattered by the sample 4 on which the ion beam 2 is incident, and the electromagnet 7 is in the direction of arrow B parallel to the ion beam 2. A facing magnetic field is generated at least from the sample 4 to the scattered ion detector 8. Further, the iris type slit 7 is arranged between the sample 4 and the scattered ion detector 8 at a predetermined position with respect to the scattered ion detector 8, and the scattered ion detector 8
The ion beam 2 incident on the sample 4 from the side is passed, and the scattered ion having a specific energy and a specific scattering angle converged on the beam axis of the ion beam 2 by the magnetic field of the electromagnet 6 is detected by the scattered ion detector. It is a disk-shaped object having an opening 71 for passing it to the 8 side. (Discrimination of Scattered Ions with Different Focusing Numbers) The parallel magnetic field type Rutherford backscattering analysis apparatus according to the embodiment of the present invention is characterized in that it is provided between the sample 4 and the iris type slit 7. A disk-shaped disk-shaped slit (movable plate-shaped slit) which is arranged so as to be movable in parallel with the ion beam 2 and has an opening 91 for passing the ion beam 2 incident on the sample 4 from the scattered ion detector 8 side. Specific example 9), and the ions which are arranged between the sample 4 and the disk-shaped slit 9 so as to be able to move parallel to the ion beam 2, and which are incident on the sample 4 from the scattered ion detector 8 side. It is a point that a cylindrical cylindrical slit (a specific example of a movable cylindrical slit) 10 having an opening 101 through which the beam 2 passes is provided.

Hereinafter, the details of the parallel magnetic field type Rutherford scattering analyzer according to the embodiment of the present invention will be described. Generally, in a uniform parallel magnetic field, charged particles generated from minute points always converge on an axis parallel to the magnetic field.
In other words, regarding the parallel magnetic field type Rutherford backscattering analyzer, in a uniform and parallel magnetic field directed in the direction of arrow B generated by the electromagnet 6, the sample 4 on which the ion beam 2 parallel to the magnetic field is incident. The scattered ions scattered by the beam always converge on the beam axis of the ion beam 2. Further, when the distance between the sample 4 and the iris type slit 7 is represented by L, the scattered ions passing through the opening 71 of the iris type slit 7 have an interval (L / N, However, N is an integer) and converges with respect to the beam axis. The integer N is the number of convergences. A part of the large number of scattered ions having different numbers of convergence N collides with the cylindrical slit 10. The axial length of the cylindrical slit 10 is L
When represented by s, scattered ions having a focusing period of N times or more that satisfy the following expression (1) always collide with the cylindrical slit 10 and do not reach the iris slit 7 because the focusing period is short. Ls> L / N (1) For example, if the axial length Ls of the cylindrical slit 10 is set so as to satisfy the following expression (2), all scattered ions that converge six times or more can be excluded. L / 6 <Ls <L / 3 (2) Further, when the number of times of focusing is even, the scattered ions always converge at a position corresponding to the center between the sample 4 and the iris type slit 7. For this reason, if the cylindrical slit 10 is arranged at a position corresponding to the center between the sample 4 and the iris slit 7, the cylindrical slit 10 is caused to collide with scattered ions having an even number of convergence times, and It can be prevented from reaching the iris type slit 7. Further, if the disk-shaped slit 9 is arranged on the side of the sample 4 from the vicinity of the iris-shaped slit 7 to the position where the ions having the number of times of convergence of 1 do not pass through the aperture 91, the scattered ions having the number of times of convergence of 1 time. Can be prevented from reaching the iris type slit 7 by colliding with the disc type slit 9. After all, if the cylindrical slit 10 that satisfies the above equation (2) is used, the number of convergences is 1, 2 by appropriately setting the positional relationship between the cylindrical slit 10 and the iris slit 7. , 3, 5 scattered ions can be discriminated.

In order to specifically explain that discrimination is possible, FIG. 2 shows three examples of the positional relationship between the cylindrical slit and the disc slit. Note that, as in FIG. 5, FIG.
Reference numeral 51 indicates a trajectory of scattered ions having one convergence time, and reference numeral 52 denotes a trajectory of scattered ions having two convergence times,
Reference numeral 53 represents the trajectories of scattered ions whose number of convergence is three, and reference numeral 54 represents the trajectories of scattered ions whose number of convergence is four. If the cylindrical slit 10 satisfies the above equation (2), scattered ions having the number of convergence of 6 or more collide with the cylindrical slit 10 and do not reach the iris slit 7. In the following, only scattered ions whose number of times of focusing is 5 or less will be considered. For example, in the example of FIG. 2A, the tip 102 of the cylindrical slit 10 is located slightly on the sample 4 side from a position corresponding to the center between the sample 4 and the iris slit 7. Further, the disc-shaped slit 9 is retracted to the closest position to the iris-type slit 7. In this arrangement, the cylindrical slit 10 blocks the central position between the sample 4 and the iris slit 7, so that the scattered ions 52, 54 having an even number of focusing times collide with the cylindrical slit 10. . When the number of times the scattered ions 5 converge is 3, the scattered ions 5 converge at a position L / 6 from the center position between the sample 4 and the iris type slit 7. Since the axial length Ls of the cylindrical slit 10 is larger than L / 6,
In the arrangement of the cylindrical slit 10 in (a), the scattered ions 53 having the number of convergences of 3 also collide with the cylindrical slit 10.
Although the trajectory of the scattered ions 5 when the number of times of focusing is 5 is not shown in FIG. 2, it corresponds to the position where the scattered ions with the number of times of focusing 5 are converged and the center between the sample 4 and the iris type slit 7. Since the distance from the position is smaller than that of the scattered ion 53 having the number of convergence of 3, the scattered ion having the number of convergence of 5 also collides with the cylindrical slit 10. Figure 2
Summarizing the example of (a), the cylindrical slit 1
With 0, all scattered ions whose number of convergence is two or more are blocked. At this time, if the disk-shaped slit 9 is retracted in the immediate vicinity of the iris-shaped slit 7, the scattered ions 51, which converge once, pass through the opening 91 of the disk-shaped slit 9, and only the scattered ions 51 are collected. Reaches the iris type slit 7. That is, in the example of FIG.
Only the scattered ions 51 whose number of times of focusing is once are discriminated. Further, in the example of FIG. 2B, the sample 4 has such a size that the rear end 103 of the cylindrical slit 10 does not block the center position between the sample 4 and the iris slit 7.
It is located on the side. Further, the disc-shaped slit 9 is
It is arranged at a position corresponding to the center between the sample 4 and the iris type slit 7. In this arrangement, the scattered ions 51, which converge once, collide with the disk-shaped slit 9 and do not reach the iris-shaped slit 7. Also,
The scattered ions having the number of convergences of 3, 4, and 5 collide with the cylindrical slit 10 and do not reach the iris slit 7. In the example of FIG. 2B, the disk-shaped slit 9 blocks the scattered ions having the number of times of convergence of 1, and the cylindrical slit 10 has the number of times of convergence of 3, 3.
4, 5 scattered ions are blocked. At this time, only the scattered ions 52 having the number of times of convergence of 2 do not collide with the cylindrical slit 10 and pass through the opening 91 of the disk slit 9. That is, in the example of FIG. 2A, the number of convergences is 2
Only scattered ions 52 are discriminated. Moreover, FIG.
In the example of (c), the center position of the cylindrical slit 10 is arranged at the center position between the sample 4 and the iris type slit 7. Further, the disk-shaped slit 9 is arranged at a position on the side of the sample 4 apart from the immediate vicinity of the iris-shaped slit 7. In this arrangement,
The scattered ions 51, which converge once, collide with the disk-shaped slit 9 and do not reach the iris-shaped slit 7. Further, since the cylindrical slit 10 blocks a position corresponding to the center between the sample 4 and the iris slit 7, the scattered ions 52 and 54 having an even number of convergences collide with the cylindrical slit 10. Also, the number of convergences is 3
Since the axial length Ls of the cylindrical slit 10 is smaller than L / 3, the scattered ions 53 of 6 do not collide with the cylindrical slit 10. Further, the scattered ions having the number of convergences of 5 are located at a position where they are converged by the sample 4 from the scattered ions 53.
It is close to the position between the iris type slit 7 and the iris type slit 7, and may collide depending on the axial length Ls of the cylindrical type slit 10. If the axial length Ls of the cylindrical slit 10 is smaller than L / 5, scattered ions having a focusing frequency of 5 do not collide. At this time, if the disk-shaped slit 9 is arranged so that either the scattered ion 53 having the number of times of convergence of 3 or the scattered ion having the number of times of convergence of 5 passes through the opening 91, the other one is the disk-type slit 9
Therefore, scattered ions having a focusing frequency of 3 or 5 can be discriminated. Thus, in the parallel magnetic field type Rutherford backscattering analyzer according to the embodiment of the present invention,
A disk-shaped slit having an opening for passing an ion beam incident on the sample from the scattered ion detector side is arranged between the sample and the iris type slit so as to be movable in parallel with the ion beam, and the scattering A cylindrical slit having an opening for passing an ion beam incident on the sample from the ion detector side is arranged between the sample and the cylindrical slit so as to be movable in parallel with the ion beam, and further, Axial length Ls of cylindrical slit
Is determined so as to satisfy the relationship of 1 / 6L <Ls <1 / 3L with respect to the distance L between the scattered ion detector and the sample, so that the number of convergences is 1, 2, 3, 5 Ions can be discriminated. As a result, it becomes possible to preferably perform energy analysis. The above-described embodiment is a preferred example, and the movable plate-shaped slit and the movable cylindrical slit in the present invention are not limited to the configurations of the disc-shaped slit and the cylindrical slit, respectively.

(Energy spectrum measurement of scattered ions
Next, as the scattered ion detector 8, its central portion
Two-dimensional with an opening through which the ion beam 2 passes
Of Scattered Ions Using Other Ion Detectors
The method of (sorting) will be described. The scattered ion detector
When a two-dimensional ion detector is used as 8,
Magnetic field strength by the electromagnet 6, the sample 4 to the slit
7-It is necessary to change the distance between the scattered ion detectors 8
There is no. This will be described below. The scattered ions
The ion at the position where the particle has reached the scattered ion detector 8
The distance r from the beam axis of the beam 2 is as described above (a5).
It is represented by a formula. Where r is a two-dimensional ion detector
Position of ions detected by the scattered ion detector 8
From (x, y) (z axis = beam axis), r = √ (x
²+ Y²), So if r is found, equation (a5)
To that position (the position where the distance from the beam axis is r)
The energy of the scattered ions that have reached is obtained. That
For example, He with the same scattering angle⁺About Aeon, 2
Ions of 300 keV and 29 under magnetic field strength around Tesla
Select ions with 9 keV (energy resolution ΔE / E
= 0.3%), the scattered ion detector 8
Position detection resolution (for example, the microchannel
Distance between the fine detection tubes) is about 0.33 mm
The degree is enough, and the position detection resolution of this level is 2
It is easy to construct a two-dimensional ion detector. Temporary
And the distance L between the sample 4 and the slit 7 is 350 m
m, distance between the slit 7 and the scattered ion detector 8
1 is 120 mm, the magnetic field strength B is 2 Tesla, and the scattering is
The radius of the detection range of the ion detector 8 is 100 mm,
If the position detection resolution is 0.33 mm, it is less than 1 keV.
With the energy resolution ΔE / E, 150 keV to 30
Scattering He in the range of 0 keV ⁺Ions can be measured at once
It has become possible to obtain
The obtained data can be obtained by one measurement. By this
Change the magnetic field strength and the positional relationship of the sample 4, etc.
It saves labor and shortens the ion irradiation time to the sample.
Therefore, contamination of the sample surface can be minimized.
In addition, the secondary such as the micro channel plate
The original position detection resolution of the scattered ion detector 8 is 0.3.
It is possible to make it smaller than 3 mm.
Obtains energy resolution below 1 keV, which was difficult
It is also possible. Detection position of the above-mentioned scattered ions
Energy calculation based on
Measurement) by, for example, the scattered ion detector 8
Calculation with an interface for capturing detection data
Machine (an example of the energy spectrum measuring means)
Just run it.

(Detection of Crystal Axis of Sample, Alignment of Axis) Next, as the scattered ion detector 8, a secondary ion detector having an opening for passing the ion beam 2 in the center thereof is used. The detection of the crystal axis of the sample 4 and the alignment of the crystal axis with the beam axis of the ion beam 2 will be described. FIG. 7 is a diagram showing a schematic configuration of a parallel magnetic field type Rutherford backscattering analyzer using a two-dimensional ion detector as the scattered ion detector 8 and a distribution of the amount of detected ions on the scattered ion detector 8. . When the beam axis of the ion beam 2 does not match (shifts) with the crystal axis of the sample 4, the crystal plane of the sample 4 is caused by a so-called blocking phenomenon in which the scattering of ions is blocked by the constituent atoms of the sample 4. The detected amount of the scattered ions scattered in the direction along is low. Therefore, for example, the beam axis of the ion beam 2 is <111 of the sample 4.
> If there is a slight deviation from the axis, the scattered ion detector 8
When the distribution of the detected amount of the scattered ions detected by the above is shown as a concentration distribution (a white portion is a portion where the detected amount of the scattered ions is low), as shown in FIG. 7 (8a), A plurality of belt-like low detection amount regions (hereinafter, referred to as low detection amount line Llow) formed in a portion where the detection amount is relatively low (including detection amount = 0) are formed. As a method of specifying the low detection amount line Llow, for example, a method in which a portion having a predetermined ratio or less with respect to the average detection amount of the whole is set as the low detection amount line Llow can be considered. Since each of the low detection amount lines Llow corresponds to each of the crystal planes of the sample 4, the beam axis O of the ion beam 2 is
The deviation between the center position O1 (intersection point) of the portion where the low detection amount line Llow intersects with each other represents the deviation between the beam axis O and the crystal axis (<111> axis) of the sample 4. Therefore, by detecting the distribution of the scattered ions only once before the measurement of the sample 4, the beam axis O
If the deviation (relative positional relationship) between the low detection line Llow and the intersection point O1 is known, the beam axis O and the sample can be adjusted by adjusting the angle at which the ion beam 2 is incident on the sample 4 by the deviation. The crystal axes of 4 can be matched (aligned).

A method of axis alignment based on the deviation between the beam axis O and the intersection O1 of the low detection line Llow will be described below. First, on the scattered ion detector 8, the distance r between the position (x, y) at which the scattered ions are detected (the beam axis O is the z axis) and the beam axis O is as described above (a4 ) Is represented by the formula. Further, an angle in the detection surface (xy plane) direction of the scattered ion detector 8 (that is, an angle when viewed from the beam axis O direction as shown in FIG. 9) is ψ (see FIG. 8), The detection position (x,
If y = ψ _b ′ in y), the angular component ψ _b of the scattering angle θ of the scattered ions in the direction parallel to the detection surface of the scattered ion detector 8 is obtained as follows. Similarly to the case of deriving the equation (a5) described above, if the time required for the scattered ions to reach the scattered ion detector 8 after passing through the slit 7 is t1, then l = vcos θ · t1
By substituting this into the expressions x and y in the expression (a2), the following expression (a6) regarding the difference Δψ _b (see FIG. 9) between ψb and ψ _b 'is derived.

[Equation 6] From this equation (a6), ψ _b can be obtained by the following equation (a7).

[Equation 7] From equations (a5) and (a7), from the position information of the intersection O1 of the low detection line Llow, the energy of the scattered ions and the angular component θ _b of the scattering angle θ of the scattered ions in the direction perpendicular to the sample surface are obtained. , The angle component ψ _{b in the} direction parallel to the sample surface can be obtained. Therefore, a predetermined incident angle adjusting means (not shown) for adjusting the angle of the sample with respect to the beam axis (that is, the angle at which the beam axis is incident on the sample) is used to move the sample to the axis in the ψ _b direction and the beam. By tilting (adjusting) the adjustment angle φ = θ _b along the plane including the axis, the beam axis and the crystal axis of the sample can be matched. In this way, axis alignment can be performed based on the deviation (that is, the coordinates (x, y)) between the beam axis O and the intersection O1 of the low detection line Llow. The detection of the crystal axis of the sample based on the detected amount distribution of the scattered ions and the calculation of the adjustment angle by the incident angle adjusting means are provided with an interface for taking in the detected amount data by the scattered ion detector 8, for example. It may be executed by a computer or the like (an example of the crystal axis detecting means). FIG. 10 shows the distribution of the amount of detected ions on the scattered ion detector 8 when the crystal axis of the sample and the beam axis O are made to coincide with each other by the method described above. Of the low detection amount). As shown in FIG. 10, it can be seen that the intersection O1 of the low detection amount line Llow and the beam axis O coincide with each other.

[0017]

As described above, according to the present invention, a plate-like movable plate-shaped slit having an opening for passing an ion beam incident on the sample from the scattered ion detector side is provided between the sample and the discrimination slit. A movable cylindrical slit having an opening through which the ion beam incident on the sample from the side of the scattered ion detector is passed, the movable cylindrical slit being disposed so as to be movable in parallel with the sample. Since it is arranged between the plate-shaped slit and the plate-shaped slit so as to be able to move in parallel with the ion beam, if the positional relationship between the movable plate-shaped slit and the movable cylindrical slit is set appropriately, the discrimination slit can be formed. Scattered ions having a specific number of times of focusing other than the specific number of focused ions to be passed are applied to the movable plate-like slit or the movable cylindrical slit, and the movable plate-like slit is used to It can be prevented from reaching the turbulent ion detector side. For this reason, it becomes possible to preferably perform energy analysis. Further, in the parallel magnetic field type Rutherford backscattering analyzer, the axial length Ls of the movable cylindrical slit is, for example, 1 / 6L <Ls with respect to the distance L between the scattered ion detector and the sample. <
If it is determined that the relationship of 1 / 3L is satisfied, it becomes possible to discriminate scattered ions having the number of convergences of 1, 2, 3, and 5.

If a two-dimensional ion detector having an aperture for passing the ion beam incident on the sample is used as the scattered ion detector, a wide range of energy spectrum can be measured by one measurement. The number of steps can be greatly reduced, and the ion beam irradiation time to the sample can be shortened, so that contamination of the sample surface can be minimized. Further, by increasing the position detection resolution of the scattered ion detector (for example, 0.33 mm or less), it becomes possible to measure the energy energy spectrum with a high resolution of 1 keV or less, which has been difficult in the past. Further, by using the two-dimensional ion detector, there is no need to provide an X-ray source and an X-ray detector, or to perform scattered ion detection for a long time while rotating the sample. The crystal axis of the sample can be detected and the axis of the crystal axis of the sample can be aligned with the ion beam in a short time and while minimizing the contamination of the sample surface.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a main part of a parallel magnetic field type Rutherford backscattering analyzer according to an embodiment of the present invention.

FIG. 2 is a diagram for specifically explaining discrimination of scattered ions having different numbers of times of focusing.

FIG. 3 is a diagram showing a schematic configuration example of a conventional parallel magnetic field type Rutherford backscattering analyzer.

FIG. 4 is a diagram showing an example of a simple appearance of a scattered ion detector.

FIG. 5 is a diagram showing trajectories of scattered ions having different numbers of convergences.

FIG. 6 is a diagram showing the relationship between the energy of scattered ions and the distance from the center of the scattered ion detector for each scattered ion having a different number of convergences.

FIG. 7 is a diagram showing a schematic configuration of a parallel magnetic field type Rutherford backscattering analyzer using a two-dimensional ion detector as a scattered ion detector and a distribution of an amount of detected ions on the scattered ion detector.

FIG. 8 is a diagram showing a scattering angle of scattered ions from a sample surface viewed from the beam axis direction of the ion beam.

FIG. 9 is a diagram showing the difference between the scattering angle of scattered ions and the angle at the position where the scattered ions reach the detector as seen from the beam axis direction of the ion beam.

FIG. 10 is a diagram showing the distribution of the amount of detected ions on the scattered ion detector when the crystal axis of the sample is aligned with the beam axis of the ion beam.

[Explanation of symbols]

2 ... Ion beam 4 ... Sample 6 ... Electromagnet 7 ... Iris type slit (aperture) 8 ... Scattering ion detector 9 ... Disk type slit 10 ... Cylindrical slits 91, 101 ... Aperture O ... Ion beam beam axis 8a ... Scattering ions Ion detection amount distribution (concentration distribution) on the detector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenichi Inoue             1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kobe Steel Co., Ltd.Kobe Research Institute F term (reference) 2G001 AA05 BA15 CA05 DA09 GA02                       GA10 GA14 KA08 SA01 SA30                 5C033 RR04 RR10                 5C038 KK12 KK13 KK17 KK20

Claims (13)

[Claims] 1. A scattered ion detector for detecting scattered ions backscattered by a sample into which an ion beam is incident, and a magnetic field parallel to the ion beam is generated at least from the sample to the scattered ion detector. The ion beam that is disposed at a predetermined position with respect to the scattered ion detector between the magnetic field generation means and the sample and the scattered ion detector, and that is incident on the sample from the scattered ion detector side A plate-like plate having an opening for passing the scattered ions having a specific energy and a scattering angle converged to the beam axis of the ion beam by the magnetic field of the magnetic field generating means to the scattered ion detector side. In a parallel magnetic field type Rutherford backscattering analyzer comprising a discrimination slit, the sample and the discrimination slit are A cylindrical movable cylindrical slit having an opening which is arranged so as to be movable in parallel with the ion beam and which allows an ion beam incident on the sample from the scattered ion detector side to pass therethrough; A cylindrical movable cylindrical slit provided between the movable plate-shaped slit and the movable plate-shaped slit so as to be movable in parallel with the ion beam, and having an opening for passing the ion beam incident on the sample from the scattered ion detector side. And a parallel magnetic field type Rutherford backscattering analyzer. 2. A length L of the movable cylindrical slit in the axial direction.
The parallel magnetic field type Rutherford backscattering analyzer according to claim 1, wherein s is set to satisfy a relationship of 1 / 6L <Ls <1 / 3L with respect to a distance L between the discrimination slit and the sample. . 3. The parallel magnetic field type Rutherford backscattering analyzer according to claim 1, wherein the scattered ion detector is a two-dimensional ion detector. 4. The energy spectrum measuring means for measuring the energy spectrum of the scattered ions based on the detection position of the scattered ions detected by the scattered ion detector. A parallel magnetic field type Rutherford backscattering analyzer according to 1. 5. A scattered ion detector for detecting scattered ions backscattered by a sample into which an ion beam is incident, and a magnetic field parallel to the ion beam is generated at least from the sample to the scattered ion detector. The ion beam that is disposed at a predetermined position with respect to the scattered ion detector between the magnetic field generation means and the sample and the scattered ion detector, and that is incident on the sample from the scattered ion detector side A plate-like plate having an opening for passing the scattered ions having a specific energy and a scattering angle converged to the beam axis of the ion beam by the magnetic field of the magnetic field generating means to the scattered ion detector side. In a parallel magnetic field type Rutherford backscattering analyzer comprising a discrimination slit, the scattered ion detector is a two-dimensional A parallel magnetic field type Rutherford backscattering analyzer characterized by being an ion detector. 6. The parallel magnetic field according to claim 5, further comprising energy spectrum measuring means for measuring an energy spectrum of the scattered ions based on a detection position of the scattered ions detected by the scattered ion detector. Rutherford backscatter analyzer. 7. The crystal axis detecting means for detecting the crystal axis of the sample based on the detected amount distribution of scattered ions detected by the scattered ion detector.
5. A parallel magnetic field type Rutherford backscattering analyzer according to any one of 1. 8. The crystal axis detecting means detects a plurality of belt-like low detection amount regions formed in a portion where the detection amount of the scattered ions is relatively low, and the sample is detected based on the low detection amount regions. 8. The parallel magnetic field type Rutherford backscattering analyzer according to claim 7, which detects the crystal axis of the. 9. The sample according to claim 1, wherein the crystal axis detection means is based on a deviation between a center position of a portion where a plurality of the low detection amount regions intersect with each other and a beam axis of the ion beam passing through the scattered ion detector. 9. The parallel magnetic field type Rutherford backscattering analyzer according to claim 8, which detects the crystal axis of the. 10. The incident angle adjusting means for adjusting the angle at which the beam axis of the ion beam is incident on the sample based on the detection result of the crystal axis detecting means. A parallel magnetic field type Rutherford backscattering analyzer according to 1. 11. A scattered ion detector for detecting scattered ions backscattered in a sample into which an ion beam is incident, and a magnetic field parallel to the ion beam is generated at least from the sample to the scattered ion detector. The ion beam that is disposed at a predetermined position with respect to the scattered ion detector between the magnetic field generation means and the sample and the scattered ion detector, and that is incident on the sample from the scattered ion detector side A plate-like plate having an opening for passing the scattered ions having a specific energy and a scattering angle converged to the beam axis of the ion beam by the magnetic field of the magnetic field generating means to the scattered ion detector side. Energy spectrum of scattered ions using a parallel magnetic field type Rutherford backscattering analyzer equipped with a discrimination slit A parallel magnetic field, which is a measuring method, wherein an energy spectrum of the scattered ions is measured based on a detection position of the scattered ions detected by the scattered ion detector which is a two-dimensional ion detector. Spectrum measurement method for scattered ions using a Rutherford backscattering analyzer. 12. A scattered ion detector for detecting scattered ions backscattered by a sample into which an ion beam is incident, and a magnetic field parallel to the ion beam is generated at least from the sample to the scattered ion detector. The ion beam that is disposed at a predetermined position with respect to the scattered ion detector between the magnetic field generation means and the sample and the scattered ion detector, and that is incident on the sample from the scattered ion detector side A plate-like plate having an opening for passing the scattered ions having a specific energy and a scattering angle converged to the beam axis of the ion beam by the magnetic field of the magnetic field generating means to the scattered ion detector side. A method for detecting a crystal axis of a sample using a parallel magnetic field type Rutherford backscattering analyzer comprising a discrimination slit, comprising: A parallel magnetic field type Rutherford backscattering analyzer characterized in that the crystal axis of the sample is detected based on the detected amount distribution of scattered ions detected by the scattered ion detector which is the next ion detector. Method for detecting crystal axis of used sample. 13. A center position of a portion where a plurality of strip-shaped low detection amount regions formed at a portion where the detection amount of the scattered ions by the scattering ion detector is relatively intersect with each other, and the scattering ion detector 13. The method for detecting a crystal axis of a sample using a parallel magnetic field type Rutherford backscattering analyzer according to claim 12, wherein the crystal axis of the sample is detected based on a deviation between the beam axis of the ion beam passing through and the beam axis.