JPH08329883A - Method and device for analyzing flight time - Google Patents

Abstract

PURPOSE: To provide a method and device for analyzing the flight time with which can be separated neutral particles from ions in better performance than conventional, reduced the possibility of turbulence application, and performed an analysis of high precision. CONSTITUTION: A pulsed beam 2 of ions produced by a pulse beam source 1 is passed through a detector 3 and cast onto a specimen 4, and particles 5 diffused from the specimen 4 are passed through a deceleration tube 6, in which the ions solely are decelerated selectively. Then the detection is made by the detector 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-of-flight analysis method and apparatus for measuring the time of flight of particles coming from an object to be measured, and more particularly, to analyzing the object to be measured from the velocity (energy) of the particles. The present invention relates to a suitable time-of-flight analysis method and apparatus.

[0002]

2. Description of the Related Art Heretofore, a time-of-flight analysis method has been known which analyzes the speed (energy) of particles by measuring the time of flight of the particles.

[0003] Such a time-of-flight analysis method includes, for example,
It is used for direct collision ion scattering spectroscopy (ICISS) and the like. In ICISS using this time-of-flight analysis method,
Since energy analysis is performed based on the difference in the arrival time of particles simultaneously scattered from the measured object, there is an advantage that the energy analysis can be performed regardless of the presence or absence of charge of the particles.

In such a method, an accelerating electrode is arranged between the object to be measured and the detector to accelerate only ions of the scattered particles, and the ions reach the detector before neutral particles. A method of separating ions and neutral particles as described above has been proposed in, for example, Japanese Patent Application Laid-Open No. 4-206432.

[0005]

However, even in the above-mentioned conventional technology, it is naturally required to be able to further separate neutral particles and ions better.
Also, for example, in order to better separate neutral particles and ions, it is necessary to increase the voltage applied to the accelerating electrode. However, if the voltage applied to the accelerating electrode is increased in this way, ionization of the residual gas occurs. However, noise is generated, and high-precision analysis cannot be performed. For this reason, it is desired that neutral particles and ions can be separated without applying a high voltage as much as possible.

[0006] The present invention has been made in view of such circumstances, and it is possible to separate neutral particles and ions better than before, and to reduce the possibility of disturbance. It is an object of the present invention to provide a time-of-flight analysis method and apparatus capable of performing more accurate analysis.

[0007]

According to a first aspect of the present invention, a detector disposed at a predetermined distance from an object to be measured detects particles flying from the object to be measured, and the particles fly. A time-of-flight analysis method for measuring time and analyzing the energy thereof, wherein a deceleration for selectively reducing the speed of ions among particles flying from the object to be measured between the object to be measured and the detector. Arranging a mechanism, so that neutral particles among particles flying from the measured object reach the detector before the ions, separating and detecting the ions and the neutral particles. It is characterized by.

According to a second aspect of the present invention, in the time-of-flight analysis method according to the first aspect, the object is irradiated with a beam to detect particles flying from the object.

According to a third aspect of the present invention, a detector disposed at a predetermined distance from the object to be detected detects particles flying from the object to be measured, and measures the flight time of the particles. A time-of-flight analyzer for analyzing the energy thereof, wherein a speed reduction mechanism for selectively reducing the speed of ions of particles flying from the object to be measured is provided between the object to be measured and the detector. The neutral particles among the particles flying from the object to be measured reach the detector before the ions, and the ion and the neutral particles are configured to be separated and detected. Features.

[0010]

According to the time-of-flight analysis method and apparatus of the present invention, neutral velocity of neutral particles can be reduced with a lower applied voltage than in the case of acceleration by selectively reducing the velocity of ions among particles flying from the object to be measured. And ions can be better separated, and more accurate analysis can be performed.

That is, the kinetic energy E of the particle
Is E = 1/2, where m is the mass of the particles and v is the velocity.
mv ² , when the same magnitude of the absolute value is applied to the ions in the acceleration direction and the deceleration direction, it is possible to change the velocity more greatly by applying the ions in the deceleration direction. The ions can be better separated. In addition, since only neutral particles are detected first, the analysis of neutral particles can be performed accurately.

[0012] Thus, when the target signal is on the heavier side (higher energy (faster flight time)), the measurement can be performed accurately without overlapping the signals.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the time-of-flight analysis method and apparatus of the present invention are applied to a time-of-flight analysis type medium energy ion scattering spectrometer will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an embodiment of the present invention. In this embodiment, a pulse beam 2 of ions generated by a pulse beam source 1 is provided at a central portion of a detector 3. The sample 4 is irradiated through the opening. Then, after the particles 5 scattered from the sample 4 pass through the speed reduction tube 6, the particles 5 are detected by the detector 3. An electric field is formed in the deceleration tube 6 by a voltage applied from the constant voltage power supply 7, and among the particles 5 scattered from the sample 4, only charged particles, that is, only ions, are selectively decelerated. It is configured as follows.

FIG. 2 shows the apparatus configuration of this embodiment in more detail. As shown in FIG. 2, the pulse beam source 1 includes a duoplasmatron ion source 10, an acceleration tube 11, a disktron It comprises a high voltage generator 12, a Q lens XY steerer 13, an analysis magnet 14, a collimator 15, a chopper 16, a chopping aperture 17, a Poschen lidar type electrostatic deflector 18, and the like.

The detector 3 is disposed in the analysis chamber 30, the sample 4 is disposed in the sample chamber 40, and the speed reduction tube 6 is disposed between the analysis chamber 30 and the sample chamber 40. I have. In this embodiment, the length between the sample 4 and the detector 3 is 60.9 cm, and the length of the reduction tube 6 is 24 cm.

Using the apparatus having the above structure, continuous 100 keV
From the helium ion (He ⁺ ), an ion pulse beam having a pulse width of 1.3 nanoseconds and a repetition frequency of 500 kHz was generated. Then, on a Si (001) surface, the room temperature is 0.1 mm.
A sample on which ² ML (1 ML = 6.78 × 10 ¹⁴ cm ⁻² ) of gold was deposited was irradiated with this ion pulse beam, and Si <0
FIG. 3 shows the measurement results of the time-of-flight spectrum obtained from the 01> axial direction.

The four measurement results shown in FIG. 1 show that the voltage applied to the deceleration tube 6 is +10.0 in order from the top.
The case of kV, +7.5 kV, +5.0 kV, and 0.0 kV is shown by correcting the delay time of the incident beam shown in Table 1. In these measurement results, the left side in the figure is Au
The right side is the scattering particles from Si, and the right side is the scattering particles from Si.

[Table 1] Table 1 shows that the voltage applied to the reduction tube 6 is +10.
It shows the results of calculating the delay time of the incident beam at 0 kV, +7.5 kV, +5.0 kV, and 0.0 kV, and the time difference between the scattered ions and the scattered particles. It can be seen that the calculation result and the calculation result match with high accuracy.

As described above, in the present embodiment, scattered ions and scattered particles can be satisfactorily separated, and a highly accurate analysis can be performed.

In the above embodiment, the case where the present invention is applied to a medium energy ion scattering spectrometer has been described. However, the present invention is not limited to this embodiment. Measurement of particles and measurement of elastic recoil particles SIMS (secondary ion
Of course, it can be applied to measurement of secondary particles in mass spectroscopy).

[0021]

As described above, according to the time-of-flight analysis method and apparatus of the present invention, neutral particles and ions can be better separated than before, and there is a possibility that disturbance is added. , And more accurate analysis can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a detailed configuration of one embodiment of the present invention.

FIG. 3 is a diagram showing a measurement result of a time-of-flight spectrum according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pulse beam source 2 ... Ion pulse beam 3 ... Detector 4 ... Sample 5 ... Scattering particles 6 ... Deceleration tube 7 ... Constant voltage power supply

Claims (3)

[Claims] 1. A flight for detecting particles flying from an object to be measured by a detector arranged at a predetermined distance from the object to be measured, measuring the time of flight of the particles, and analyzing the energy of the particles. In the time analysis method, a deceleration mechanism for selectively reducing the speed of ions among particles flying from the object to be measured is provided between the object to be measured and the detector, and A time-of-flight analysis method, wherein neutral ions among the flying particles reach the detector before the ions, and the ions and the neutral particles are separated and detected. 2. The time-of-flight analysis method according to claim 1, wherein the object is irradiated with a beam and particles flying from the object are detected. 3. A flight for detecting particles flying from the object to be measured by a detector arranged at a predetermined distance from the object to be measured, measuring the time of flight of the particles, and analyzing the energy of the particles. In the time analyzer, a deceleration mechanism for selectively reducing the speed of ions among particles flying from the object to be measured is provided between the object to be measured and the detector, and A time-of-flight analyzer characterized in that the neutral particles of the flying particles reach the detector before the ions, and the ions and the neutral particles are separated and detected. .