JPH10312766A - Ion scattering spectroscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small ion scattering spectroscope shortened in length in the axial direction and reduced with the number of electrodes and number of part items by integrating a chopping mechanism chopping a beam into pulses and an ion source, and making it movable in the direction perpendicular to the axis of a coaxial detector. SOLUTION: An ion source 21 and a chopping electrode 2 positioned by mechanical machining are made integrally movable in the direction perpendicular to the axis of an ion beam so that the ion beam passes through the center of the chopping electrode 2 by molded bellows 3 and a moving stage 4. The moving stage 4 is driven, and the ion source 21 and chopping electrode 2 are moved against a chopping aperture 25 for positioning so that the ion beam passes through the chopping aperture 25. The molded bellows 3 are deformed to follow the movement and keep the internal decompressed state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion scattering spectrometer for colliding ions with a sample and detecting scattered ions for element identification.

[0002]

2. Description of the Related Art Ion scattering spectroscopy (Ion scattering spectroscopy) for performing elemental analysis of a sample surface by irradiating a sample with an ion beam having a constant energy and good parallelism and detecting ions scattered at a predetermined detection angle. ISS: Ion Scat
tering Sperctroscopy) is known, and the scattering angle is 18
Direct impact ion scattering spectroscopy (ICISS: Quantitative) by detecting ions scattered near 0 °
Impact-Collision Ion Scattering Sperctroscopy) was developed, and the ion source and detector were arranged coaxially to make the scattering angle completely 180 °.
ct-Collision Ion Scattering Sperctroscopy) has been developed.

FIG. 6 is a schematic configuration diagram of a coaxial direct impact ion scattering spectrometer. 6, the coaxial direct impact ion scattering spectrometer has an ion source 21, a coaxial detector 26, and a sample 11 arranged coaxially, and controls opening and closing of an ion beam emitted from the ion source 21 by a chopping electrode 22. The sample is made incident on the sample 11 and ions scattered in the 180 ° direction are detected by the coaxial detector 26, and a start signal from the chopping control device 32 for controlling the chopping electrode 22 is obtained through the preamplifier 40 from the coaxial detector 26. TDC (Time to Digital Conv.)
eter) 41 to measure the flight time of the scattered ions,
The data processor 42 performs element identification of the sample. In the above apparatus, the deviation of the direction of the ion beam emitted from the ion source in the direction perpendicular to the axis (broken line in the figure) is corrected, and the ion beam passes through the chopping electrode 22 or the chopping aperture 25 and is transferred to the sample 11. A beam position adjusting mechanism such as a beam deflecting electrode 23, 24 called a steerer is provided so as to be directed. In general, a coaxial direct impact ion scattering spectrometer has a lens system 7 arranged along the axis to focus the ion beam.

[0004] Since the chopping electrode and the ion source are constituted by mechanisms independent of each other and are fixed to separate flanges, it is necessary for the ion beam emitted from the ion source to pass through the center between the chopping electrodes. Therefore, a beam adjusting mechanism combining a beam deflection electrode is required.

For example, in the adjustment of the beam position by an electric field, the beam deflection electrodes 23 and 24 are constituted by two pairs of electrodes provided to face each other in the X and Y directions. Insulated and installed. Each electrode is taken out to the outside through a feedthrough opened in the case 20 and connected to an applied voltage power supply.

The above-mentioned apparatus includes an ion controller 31, power supplies 33 and 34, and a detector power supply 36 for supplying power to each section, and further includes a chopping electrode, an ion beam position adjusting mechanism, and a coaxial detector inside. Case 2 to store
0 is an oil rotary pump 50, turbo molecular pumps 51 and 52
And so on. Further, a gate valve 12 is provided between the sample chamber 10 containing the sample 11 and the case 20.

[0007]

In the conventional coaxial direct collision ion scattering spectrometer, the ion beam position adjusting mechanism is arranged on the axis between the ion source and the coaxial detector. Is difficult. Usually, the alignment mechanism requires a length of 20 cm or more, which is a large ratio to the total length of the coaxial direct impact ion scattering spectrometer. For this reason, in a coaxial direct collision ion scattering spectrometer that requires miniaturization, the axial length cannot be reduced due to the ion beam position adjustment mechanism.

In the conventional coaxial direct impact ion scattering spectrometer, a plurality of electrodes used for an ion beam position adjusting mechanism are mounted in a case, so that an insulator for insulation, a feed-through for extracting electrodes, a power supply for applied voltage, etc. In addition, there is a problem that the manufacturing process is complicated because a plurality of electrodes are attached, and there are also parts for ultra-high vacuum, which leads to an increase in manufacturing cost.

Accordingly, the present invention has been made to solve the above-mentioned problems, and to provide a small-sized ion scattering spectrometer in which the length in the axial direction is reduced and the number of electrodes and the number of accessory components are reduced. Aim.

[0010]

SUMMARY OF THE INVENTION According to the present invention, an electrode mechanism for alignment that has been required conventionally is used without using an electrode mechanism.
It enables positioning of the ion beam with respect to the chopping aperture and the chopping electrode,
As a result, the axial length of the coaxial direct impact ion scattering spectrometer can be reduced, and the number of electrodes and the number of attached components can be reduced, thereby enabling downsizing.

An ion scattering spectrometer according to the present invention is an apparatus in which an ion source and a coaxial detector are arranged coaxially, and the coaxial detector detects scattered ions scattered at an angle near 180 °. The electrode for positioning is omitted and the size is reduced by integrating the chopping mechanism for ionizing the pulse with the ion source and moving in the direction perpendicular to the axis. The position between the chopping mechanism and the ion source can be aligned by mechanical processing.

According to the ion scattering spectrometer of the present invention, the position between the chopping mechanism and the ion source is adjusted by mechanical processing, and the intensity of the scattered beam due to the ion beam emitted from the ion source is detected by a coaxial detector. The movable mechanism is driven while monitoring the detection intensity, and the chopping mechanism and the ion source are moved integrally in a direction perpendicular to the axis, thereby moving the ion beam parallel to the axis. Then, the position is adjusted so that the detected intensity becomes a predetermined value. Through the above operation, the ion beam can be aligned with the position passing through the center between the chopping electrodes and the chopping aperture.

According to a first embodiment of the present invention, a chopping electrode and a lens system for focusing a beam are integrated, the integrated structure is aligned with an ion source by machining, and a direction perpendicular to an axis is moved by a movable mechanism. Is relatively movable with respect to.

In a second embodiment of the present invention, the ion source and the chopping electrode are connected by a molded bellows, and the chopping electrode is housed inside the molded bellows, whereby the chopping electrode is isolated from the outside. In the state, it can be movable.

In a third embodiment of the present invention, a configuration in which a chopping electrode and a lens system are integrated and an ion source are connected by a molded bellows, and the chopping electrode and the lens system are housed inside the molded bellows. Thus, the chopping electrode and the lens system can be moved while being shielded from the outside.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are a schematic block diagram and a sectional view for explaining an ion scattering spectrometer of the present invention. FIGS. 1 and 2 show only a device for adjusting the ion beam position in the coaxial direct collision ion scattering spectrometer shown in FIG. Ion beam position adjusting device 1 in ion scattering spectrometer of the present invention
Is provided with a molding bellows 3 and a movable stage 4 for integrally adjusting the displacement of the ion source 21 and the chopping electrode 2 for pulsing the ion beam with respect to the chopping aperture 25. Further, the ion source 21 and the chopping electrode 2 side can be aligned by mechanical processing.

1 and 2, a coaxial detector 26 and a chopping aperture 2 having an opening coaxially with the central opening of the coaxial detector are provided on the sample side in the case 20.
5 is provided and fixedly attached to the ion scattering spectrometer main body. An ion source 21 is provided at the end of the case on the chopping aperture 25 side with the formed bellows 3 and the movable stage 4 interposed therebetween.

The chopping electrode 2 is an electrode for pulsing the ion beam emitted from the ion source 21. The chopping electrode 2 can be composed of a pair of electrodes that are opposed to each other with the ion beam axis interposed therebetween. Attach it with the side. This chopping electrode 2 is attached, for example,
The molded bellows 3 can be fixed to a member such as a flange on the ion source 21 side and housed in the molded bellows 3. Further, insulation between the chopping electrode 2 and the main body and supply of voltage to the chopping electrode 2 can be performed by a configuration formed on the flange portion side. Further, the mounting position of the chopping electrode 2 with respect to the chopping aperture 25 is adjusted so that the center lines of the two electrodes of the chopping electrode 2 pass through the chopping aperture 25.

By driving the movable stage 4,
The ion source 21 and the chopping electrode 2 move in a plane orthogonal to the ion beam axis. by this,
The ion source 21 and the chopping electrode 2 are integrated, and the ion beam moves parallel to the axis.

The ion beam is pulsed by the chopping electrode 2 by changing the voltage applied to the pair of chopping electrodes to deflect the ion beam and to control the passage and non-passage of the ions to the chopping aperture 25. In the time-of-flight measurement method, the timing of the pulsing of the chopping is important. In order for the timing of the pulsing of the ion beam to be accurate, the ion beam from the ion source 21 is chopped when the ion beam is not deflected. It must pass through the center between the electrodes and the chopping aperture. The molded bellows 3 and the movable stage 4 of the present invention are configured so that the ion source and the chopping electrode can be moved integrally in a direction orthogonal to the ion beam axis, and mechanically process the ion source and the chopping electrode side. To adjust the position of the ion beam so as to pass through the center of the chopping electrode. The movable stage mechanism corrects the ion beam misalignment so that the ion beam passes through the chopping aperture.

The molded bellows 3 is connected in a sealed state between the case end on the chopping aperture 25 side and the case end on the ion source 21 side, and the chopping electrode 2 is arranged inside. When the movable stage 4 is moved, the ion source 2 moves integrally with the chopping electrode 2 in a direction perpendicular to the ion beam axis with respect to the chopping aperture 25. The molded bellows 3 is deformed following this movement and maintains the internal reduced pressure state. Therefore, the ion source 21 and the chopping electrode 2 are integrally moved with respect to the ion beam axis by the machining accuracy between the ion source and the chopping mechanism, and the moving mechanism of the forming bellows 3 and the movable stage 4. Are aligned on the axis, the ion beam emitted from the ion source 21 can pass through the center between the chopping electrodes, the central opening of the chopping aperture 25 and the coaxial detector 26, and be incident on the sample. .

The operation of adjusting the displacement of the ion beam will be described below with reference to FIGS. Note that the cross-sectional view of FIG. 2 shows a state before the positional deviation between the ion source and the chopping aperture is adjusted, and the cross-sectional view of FIG. 3 shows a state after the positional deviation between the ion source and the chopping aperture is adjusted. Only the part of the scattering spectrometer for adjusting the position of the ion beam is shown.

In FIG. 2, the ion source 21 and the chopping electrode 2 are aligned by machining, and the ion source 21 and the chopping aperture 25 are not properly aligned. , A position shifted from the chopping aperture 25. In order to adjust the displacement, the movable stage 4 is driven to move the ion source 21 and the chopping electrode 2 with respect to the chopping aperture 25, and the ion beam 21 is positioned so that the ion beam passes through the chopping aperture 25.

When the movable stage 4 is moved, the ion source 21 and the chopping electrode 2
5 moves integrally. The molded bellows 3 is flexible and has a characteristic of being easily deformed by an external force. Therefore, the formed bellows 3 is deformed following the displacement generated by driving the movable stage 4. At this time, the inside of the molded bellows 3 can be kept in a reduced pressure state, and interference with the chopping electrode 2 disposed inside can be prevented.

The alignment of the ion beam can be performed by emitting the ion beam from the ion source 21 and monitoring the output with the coaxial detector 26. A part of the emitted ion beam is a chopping aperture 2
5 and the central opening of the coaxial detector 26 to reach the sample. The coaxial detector 26 detects 180 °
To detect the scattered ions and output a detection output.

At this time, if the positions of the ion source 21 and the chopping aperture 25 are deviated, the movable stage 4 is driven until an output is obtained, and then the ion beam passes through the center of the chopping aperture 21. Perform positioning.

The positioning of the ion beam with respect to the chopping aperture can be performed, for example, by adjusting the movable stage 4 so that the intensity of the detection output is maximized. The trajectory of the ion beam at the time when the intensity of the detection output is maximum is the center between the chopping electrodes, the chopping aperture 25, and the coaxial detector 26.
Trajectory passes through the central opening of the movable stage 4, whereby the ion beam can be positioned by the movable stage 4.

Further, the position of the ion beam can be adjusted by controlling the pulse voltage applied to the chopping electrode and monitoring the intensity of the detection output.

Next, another configuration example of the ion scattering spectrometer of the present invention will be described with reference to FIG. In the configuration example shown in FIG. 4, a chopping electrode and a lens system for focusing a beam are integrated, and the integrated configuration can be integrally moved in a direction orthogonal to the ion beam axis. In FIG. 4, a support member 27 is provided on a flange of the molded bellows 3, and the chopping electrode 2 and a lens system 27 for beam focusing are attached to the support member 27. Thereby, the chopping electrode 2 and the lens system 27 for beam focusing can be integrally formed, and the positional deviation can be adjusted integrally with the chopping aperture 25. Further, the alignment with respect to the ion source can be performed by adjusting by machining.

Next, another configuration example of the ion scattering spectrometer of the present invention will be described with reference to FIG. In the configuration example shown in FIG. 5, the chopping electrode is fixed to the case on the coaxial detector 26 side, and one end of the chopping electrode 2 is attached to the flange on the case 20 side.
It is placed in the bellows 3 itself. Thereby, the same effect as that of the configuration shown in FIG. 1 can be obtained. The operation of the configuration example shown in FIGS. 4 and 5 is the same as that of the configuration example shown in FIG. 1, and a description thereof will be omitted.

According to the ion scattering spectrometer of the present invention, an electrode for adjusting the passage of the ion beam to the center between the chopping electrodes can be omitted, so that the length in the axial direction can be reduced and the size can be reduced. Can be.

[0032]

As described above, according to the ion scattering spectrometer of the present invention, the length in the axial direction can be reduced, and the number of electrodes and the number of attached components can be reduced to reduce the size. it can.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram for explaining an ion scattering spectrometer of the present invention.

FIG. 2 is a sectional view for explaining an ion scattering spectrometer of the present invention.

FIG. 3 is a sectional view for explaining the operation of the ion scattering spectrometer of the present invention.

FIG. 4 is a cross-sectional view for explaining another configuration example of the ion scattering spectrometer of the present invention.

FIG. 5 is a cross-sectional view for explaining another configuration example of the ion scattering spectrometer of the present invention.

FIG. 6 is a schematic configuration diagram of a coaxial direct impact ion scattering spectrometer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ion beam position adjusting device, 2 ... Chopping electrode, 3 ... Molding bellows, 4 ... Movable stage, 7 ... Focusing lens system, 10 ... Chamber, 11 ... Sample, 12 ... Gate valve, 20 ... Case, 21 ... Ion Source, 22: chopping electrode, 23: deflector, 24: steerer, 2
5 chopping aperture, 26 coaxial detector, 2
7 ... Supporting member, 31 ... Ion source power supply, 32 ... Chopping controller, 33 ... Deflector power supply, 34 ... Stealer power supply, 36 ... Detector power supply, 40 ... Preamplifier, 41 ...
TDC, 42: Computer, 50: RP, 51: TM
P, 52 ... TMP.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryuji Nishihara 380-1 Matsuba, Horiyamashita, Hadano-shi, Kanagawa Inside the Hadano Plant of Shimadzu Corporation

Claims (1)

[Claims] 1. A coaxial direct collision ion scattering spectrometer in which an ion source and a coaxial detector are arranged coaxially and a scattered ion scattered at an angle near 180 ° is detected by the coaxial detector. An ion scattering spectrometer characterized by being integrated with a chopping mechanism for ionizing a pulse and an ion source and being movable in a direction orthogonal to the axis.