JPH0426045A - Charged particle energy analyzing device - Google Patents

Abstract

PURPOSE:To provide a high energy resolution without causing a large sized construction of the device concerned, by furnishing an electrostatic lens for beam deceleration, decelerating an ion beam incident to between flat plate electrodes in parallel arrangement, and at the same time, suppressing dispersion of the beam. CONSTITUTION:An ion beam consisting of charged particles having passed through plasma is left incident between parallel electrodes 10a, 10b on which a specified voltage is impressed 11, and the energy of charged particles is analyzed on the basis of the distance at which the ion beam deflected by the electric field thus generated has attained. In this device, a beam decelerating electrostatic lens 12 is provided consisting of a plurality of electrodes to generate an electric field E2 which decelerates the ion beam and suppresses its spread along the incident path when ion beam is cast onto the parallel electrodes 10a, 10b. Because ion beam is decelerated, it is no more needed to lengthen the ion beam attaining distance. This provides a high energy resolution without causing the device to be constructed in a large size.

Description

[Detailed Description of the Invention] [Purpose of the Invention] [Industrial Application Field] The present invention is capable of analyzing the energy of charged particles passed through a plasma, and is capable of analyzing the energy of charged particles used for measuring the spatial electric field of the plasma. Regarding analysis equipment.

[Conventional technology]

2. Description of the Related Art Charged particle energy analyzers are conventionally known as devices that can measure various parameters of plasma, and in particular can directly and locally measure the spatial potential of plasma.

FIG. 3 shows a conceptual diagram of a heavy ion beam probe device equipped with a charged particle energy analyzer. In this device, an ion beam generated in an ion generating section is adjusted to a predetermined angle of incidence by a sweep plate 2 and is made incident into a plasma 3. The ion beam that entered the plasma 3 undergoes − due to interaction with the plasma (electron collision, ionization reaction).
The valence heavy ion beam emerges as a secondary ion beam having a charge number of two or more, and enters the charged particle energy analyzer 4, where its energy is analyzed. The intensity, energy, and momentum of the ion beam that has passed through the plasma 3 contain various parameter information indicating the state of the plasma.

Therefore, by adjusting the energy and angle of incidence of the ion beam that is incident on the plasma 3 and making the ion beam incident on an arbitrary observation point, the energy analysis of the ion beam that has passed through that part can be performed to obtain a local space of the plasma. The potential can be measured, and two-dimensional observation becomes possible by injecting an ion beam across the plasma cross section.

FIG. 4 shows the energy analysis principle of the charged particle energy analyzer 4.

A voltage from the high-voltage power source 6 for deflection is applied to the parallel plate electrodes 5a5b which are arranged parallel to each other to face each other.
A parallel plate electrode 5a generates an electric field E between a and 5b.

An ion beam is made to enter between 5b and 5b. Parallel plate electrode 5a
. At the expected arrival position of the ion beam deflected by the electric field E, there is a beam position detector 7 equipped with two metal plates 7a and 7b arranged close to each other and electrically connected to each other as shown in FIG. is set up. Since the beam profile of the ion beam formed on the metal plates 7a and 7b moves in the left and right directions in the figure depending on the reach distance, the beam profile of the ion beam formed on the metal plates 7a and 7b moves in the left and right directions in the figure depending on the beam profile formation ratio.

After amplifying the current output from each of the currents 7b with an amplifier 8, the currents are led to a measurement system, where the distance traveled by the ion beam is determined from the ratio of the two signals. Since the travel distance X of the ion beam is proportional to the energy U of the ion beam, the energy of the ion beam can be detected from the detected travel distance X.

Incidentally, measurement of plasma potential using a heavy ion beam generally requires an energy resolution of 10-6. The energy resolution of the charged particle energy analyzer described above depends on the spatial resolution of the beam position detector 7. In addition, the electric field E applied between the parallel plate electrodes 5a and 5b
If the distance X is increased by a factor of n by weakening the energy, the energy resolution will be improved by a factor of n even if the detector has the same resolution.

However, the analyzer itself needs to be large enough to accommodate the n-times the reach distance.

In order to achieve an energy resolution of 10-6, for example, if the beam reach distance (X) is 500 mm, a spatial resolution of 5001.0-6-51.0-7 μm -0.5 μm is required, In reality, it is extremely difficult to achieve such resolution.

On the other hand, the beam position detector 7 detects the charge of the ion beam incident on the two metal plates 7a and 7b arranged close to each other as a current as described above,
Currents 1.7b and 7b respectively output. , I2 is used to detect the reached position. 2 metal plays) 7a, 7b
When the beam shape formed above is axa, the arrival position P is P= (a/2) (12II)/(12I
l). Therefore, the accuracy of the detected position depends on the linearity and drift of the amplifier 8, as well as the A/
It depends on the D conversion accuracy etc.

For example, if the measurement accuracy of currents II and I2 is 5X101,
When a-10 mm, the measurement accuracy (positional resolution) ΔP is as follows.

Conversely, with this position resolution (1.75 μm), 1o-6
In order to obtain an energy resolution of
needs to be 1750 mm, which is not realistic considering the deterioration in assembly accuracy of such a large analyzer.

[Problem to be solved by the invention]

Therefore, conventional charged particle energy analyzers have a problem in that it is difficult to achieve high energy resolution while limiting the size of the device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a charged particle energy analyzer that can realize extremely high energy resolution such as U-O-6 without increasing the size of the device.

[Structure of the Invention [Means for Solving the Problems]] In order to solve the above-mentioned problems, the present invention provides an ion beam consisting of charged particles that has passed through a plasma between parallel electrodes to which a predetermined voltage is applied. In a charged particle energy analyzer that analyzes the energy of the charged particles based on the reach of the ion beam, which is deflected by an electric field applied between the parallel electrodes, the ion beam is incident on the parallel electrodes. The beam deceleration electrostatic lens is provided along the incident path when the ion beam is incident, and includes a plurality of electrodes that generate an electric field that decelerates the ion beam and suppresses its spread.

[For production]

By taking the above measures, the present invention decelerates the ion beam incident between the parallel electrodes by the electric field generated by the electrostatic lens for beam deceleration, suppresses its spread, and focuses the ions. Becomes a beam. The ion beam decelerated in this manner is deflected by the electric field between the parallel electrodes and reaches a predetermined position. Since the ion beam is decelerated, an energy resolution of 10-6 can be obtained without increasing the reach of the ion beam.

〔Example〕

Examples of the apparatus of the present invention will be described below.

FIG. 1 is a diagram showing the principle of detecting charged particle energy in this embodiment. The device according to this embodiment has parallel plate electrodes 10
A high-voltage power supply 11 for beam deflection is connected to g and 10b, and the parallel plate electrode 1 of the ion beam that has passed through the plasma
0a, 1. An electrostatic lens 12 for beam deceleration is installed at a position of incidence between the beams. The beam deceleration electrostatic lens 12 is composed of a plurality of annular electrodes arranged at a predetermined distance from each other, and is arranged so that the ion beam passes through a tunnel formed by a hollow circle of these annular electrodes. Each annular electrode is connected to an adjacent annular electrode via a resistor, and the annular electrode 1.2a at one end closest to the parallel plate electrode 10b is connected to the parallel plate electrode 10b, and the annular electrode at the other end is connected to the parallel plate electrode 10b. It is grounded. A voltage is applied to the beam deceleration electrostatic lens 12 configured in this way from a beam deceleration high voltage power source 13.

On the other hand, a beam position detection fluorescent plate 14 is located at the expected beam arrival position of the parallel plate electrode 10b on the ion beam incidence side.
is provided. This beam position detection fluorescent plate 14
A lens 15 is arranged facing each other, and this lens 15
A beam position detector] 6 consisting of two-dimensionally arranged photosensors is installed at the imaging position. The output signal from the beam position detector 16 is guided to the measurement system via an amplifier]7.

Next, the operation of this embodiment configured in this manner will be explained.

When a voltage is applied to the beam deceleration electrostatic lens 12 from the deceleration high-voltage power source 13, a beam is generated in the tunnel formed by the plurality of annular electrodes of the beam deceleration electrostatic lens 12 in a direction opposite to the direction of incidence of the ion beam. An electric field E2 is generated. As a result, the ion beam that has entered the electric field E2 of the electrostatic lens 12 for beam deceleration is decelerated. Parallel plate electrodes 10a, 10
The ion beam that is decelerated and enters between the parallel plate electrodes ], Oa, ], and the electric field E applied between Ob
], and depending on the energy, the light beam enters a predetermined position in the area where the position detection fluorescent plate 14 is installed. At this time, the ion beam incident on the installation location of the position detection fluorescent plate 4 is focused by the lens effect of the beam deceleration electrostatic lens 12 so that the beam shape is not diffused. Note that this lens effect is determined by the distance between each annular electrode, applied voltage, and the like.

Here, the energy U of the ion beam is reduced by deceleration of the ion beam by the beam deceleration electrostatic lens 12.

becomes 1/n, then the relationship between energy resolution ΔU and spatial resolution ΔX is ΔU/(Uo
/n) -ΔX/X ,, ΔU/Uo-n-'-ΔX/X Therefore, ΔU/Uo-10 ΔX/X=1.75μm1500mm -3,5X 1
0-6, if n-3.5, an energy resolution of ]0-6 and a spatial resolution of 1.75 μm can be achieved.

On the other hand, when the ion beam deflected between the parallel plate electrodes 10a and 10b enters a predetermined arrival position, the arrival position of the position detection fluorescent plate 14 emits light.

This optical image is formed by the lens 15 on the light receiving surface of the beam position detector 16, and the arrival position detection signal obtained by photoelectrically converting this optical image is amplified by the amplifier 17 and then transmitted to the measurement system. The measurement system determines the arrival position of the ion beam from the arrival position detection signal.

According to this embodiment, the beam deceleration electrostatic lens 1
2, the ion beam incident between the parallel plate electrodes 10a and 10b is decelerated and beam dispersion is suppressed, so the requirement for the resolution of the position detector can be reduced without increasing the size of the device, and it can be easily An energy resolution of 10-6 can be achieved.

Further, the reached position detecting section is provided with a position detecting fluorescent plate 14, and the light emitted from the position detecting fluorescent plate 14 is detected, so that the lens 15, the position detector 16. The reached position detection system such as the amplifier 17 is insulated from the parallel plate electrode 10b to which a high voltage is applied, and the reached position detection system electrically connected to the parallel plate electrode 10b as in the conventional case is There is no need to take countermeasures such as floating the vehicle, and costs can be reduced. Furthermore, by increasing the magnification of the lens 15, it is possible to improve the positional resolution, and more accurate energy analysis is possible.

Note that the present invention is not limited to the above embodiment. For example, the position detector 7, amplifier 8. The electrical/optical converter 21 with an A/D conversion function is set to the same high potential as the parallel plate electrode 10b, and the detection signal is transmitted via an optical cable 23 to the optical/electrical converter 22, which is at ground potential. It is also possible to obtain the effects of the present invention, such as realizing a high energy resolution that meets the requirements without increasing the size of the device.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a charged particle energy analyzer that can realize an extremely high energy resolution of 10-6 without increasing the size of the device.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of charged particle energy analysis according to an embodiment of the present invention, Fig. 2 is a configuration diagram of a modified part of the arrival position detection system of the same embodiment, and Fig. 3 is a conventional heavy ion beam probe device. FIG. 4 is a diagram showing the principle of conventional charged particle energy analysis, and FIG. 5 is a diagram showing a beam receiving surface of a position detector. 10a, 10b... Parallel plate electrodes, 11... High voltage power source for beam polarization, 12... Electrostatic lens for deceleration, 13.
... High-voltage power supply for beam deceleration, 14 ... Luminescent plate for position detection, 15 ... Lens, 16 ... Position detector, 17
··Amplifier.

Claims (2)

[Claims] (1) An ion beam consisting of charged particles that has passed through a plasma is made incident between parallel electrodes to which a predetermined voltage is applied, and the distance traveled by the ion beam is deflected by the electric field applied between the parallel electrodes. In a charged particle energy analyzer that analyzes the energy of the charged particles based on A charged particle energy analyzer characterized by being provided with a beam deceleration electrostatic lens consisting of a plurality of electrodes that generate an electric field. (2) A position detection fluorescent plate installed at the expected arrival position of the ion beam and emitting light at a location corresponding to the arrival position, and a lens that forms a light image from this position detection fluorescent plate at a predetermined imaging position. 2. The charged particle energy analyzer according to claim 1, further comprising: an optical position detector installed at the imaging position of the lens and outputting an arrival position detection signal obtained by photoelectrically converting the optical image.