JPH0135469B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an apparatus for analyzing the surface of a solid, and more particularly to a surface analysis apparatus for analyzing sputtered particles by bombarding the surface of a sample with ions.

[Prior art and its problems]

In recent years, surface analysis devices have become popular in factories, research institutions, etc., and there are many types, and one suitable for the application is selected.

In nuclear fusion research, it is important to study plasma-wall interactions that supply impurities to the plasma. This application requires the ability to analyze isotopes of hydrogen, which is considered a fuel, and helium, an ash material. A secondary ion mass spectrometer is a surface analyzer that can analyze hydrogen, helium, etc. This method involves irradiating a sample with primary ions and performing mass spectrometry on the ions among the particles spattered from the surface. Conventionally, there were two problems when attaching a secondary ion mass spectrometer to a nuclear fusion device and using it for research on plasma-wall interactions.

In addition to ions, a large amount of working gas (the gas that should become the primary ions) flows out from the ion source that generates primary ions for sample irradiation, but measures are needed to prevent this working gas from contaminating the fusion device. It is. Countermeasures include differential pumping of the ion beam beam line, but this poses a problem in that the apparatus becomes large and complicated. This is the first problem.

On the other hand, the yield of secondary ions used in secondary ion mass spectrometry, that is, the number of secondary ions per primary ion, is very small, so secondary ion mass spectrometry requires extremely sensitive measurement. Requires equipment. This is the second problem.

[Object of the invention] The present invention was made in view of the above circumstances, and
The objectives are, firstly, to provide a simple and compact mass spectrometer suitable for use in nuclear fusion devices, etc., and secondly, to provide a mass spectrometer that can function without the use of highly sensitive measurement equipment. The goal is to provide equipment.

[Summary of the invention]

In order to achieve the above object, the present invention forms a secondary ion generating section that generates ions of a surface substance of a sample using a vacuum container, an anode and three cathodes housed in the vacuum container, and the anode has a penetrating A first and a second cathode are disposed in both openings of the hollow part so as to cover the respective openings, and an anode is disposed in the first and second cathodes. a through hole coaxial with the hollow portion, a third cathode for holding a sample to be surface analyzed in the second through hole, and
means for applying a magnetic field substantially parallel to the axis of the hollow part of the anode in the hollow part of the anode, the highest in the anode, the second cathode in the first cathode and the third cathode; A secondary ion generator used for surface analysis was constructed by means of applying a potential higher than each potential.

〔Effect of the invention〕

According to the present invention, the sample is disposed facing the discharge space, and the potential distribution in the discharge space is adjusted such that primary ions generated by the discharge collide with the sample surface with high energy, thereby removing spatters from the surface material of the sample. In addition to increasing the amount of primary ions, the sample is irradiated with high gas efficiency using a small and simple device that does not use a differential pumping system.
Neutral atoms, which make up most of the particles on the surface of the sputtered sample, can be ionized by a group of high-temperature, high-density electrons confined in the discharge space, generating a large amount of secondary ions. There is no need to use highly sensitive measurement equipment to detect

[Embodiments of the invention]

FIG. 1 is a longitudinal sectional view of the main parts of a surface analysis device showing one embodiment of the present invention. The vacuum container 1 is connected to an exhaust device and a gas supply device (not shown) through a port 2, and inside the vacuum container 1 is a cylindrical anode 3, which is spaced apart so as to cover the opening of the hollow portion 4 of the anode 3. and a first cathode 5 disposed adjacent to the first cathode 5; a through hole 6 is provided in the center of the first cathode 5, and the first cathode 5 is disposed so as to cover the other opening of the hollow portion 4 of the anode 3; The second cathode 7 is provided with a through hole 8 coaxial with the hollow portion 4 of the anode. 9 is arranged apart from and close to the second cathode 7, and holds the sample 10 arranged in the through hole 8 of the second cathode in the holder 1.
This is the third cathode held together with 1. The holder 11 has a terminal 1 to which a power output (not shown) is applied.
It also serves as a power feeding path from the second cathode 9 to the third cathode 9. The first cathode 5, the second cathode 7 and the third cathode 9
is supported by a column supported by a support part (not shown) inside the port 2, and the first cathode 5
And the second cathode 7 is supplied with power by the pillar. The anode 3 is supported by the vacuum container 1 which is grounded via the port 2, and is electrically grounded.
A device for analyzing the mass of ions is provided at a distance from and close to the first cathode 5 . Although the present invention does not impose any restrictions on the method of mass spectrometry of secondary ions, an ion velocity selection device 13 is used in this embodiment. 14 is an ion detection device. The ion velocity selection device 13 consists of two conductive plates that are insulated from each other and a case that accommodates them. The ion detection device 14 uses a Faraday cup. Ion velocity selection device 13
The ion detection device 14 has an electrically conductive path inside and is supported by a support column 15 supported by a support section inside the port. The anode 3, the first cathode 5, the second cathode 7, the third cathode 9, the ion velocity selection device 13, and the ion detection device 14 are housed in the vacuum container 1.

A coil 16 provided around the outer periphery of the vacuum container 1 constitutes a magnetic field generator together with a power source (not shown). The energized coil 16 applies a magnetic field substantially parallel to its axis throughout the anode cavity 4 and applies a substantially uniform magnetic field to the ion velocity selection device.

FIG. 2 is an explanatory diagram of the operation of the main parts of the surface analysis device of the present invention. Parts common to those in FIG. 1 are designated by the same numbers to avoid duplication of explanation. Although the coil 16 is not shown in FIG. 2, the description will be made assuming that a magnetic field is applied to the anode during operation. Also, the second cathode 7
is given a negative potential by the power supply 17,
A potential lower than the potential of the second cathode 7 is applied to the first cathode 5 by power sources 17 and 18, and to the third cathode 9 by power sources 17 and 19, respectively.

The operation of the present invention will be explained below with reference to FIGS. 1 and 2. In this embodiment, a gas to become primary ions, such as argon, is supplied to the vacuum vessel 1 through the port 2 and reaches the hollow part 4 of the anode. In the hollow part 4 of the anode, a cross-field discharge is generated and self-sustaining due to the applied magnetic field and the electric field created by the voltage between the electrodes. In order to sustain stable discharge, the potential of the second cathode 7 must be higher than the potential of the first cathode 5. Hollow part 4 of anode
A group of high-temperature, high-density electrons are trapped in the gas, which ionizes gas molecules. Ionized molecules (for example, atomic ions of argon) move in the hollow part 4 of the anode due to the force received from the electromagnetic field, and some of them move in the direction of the sample, and then move between the second cathode 7 and the sample 1.
Due to the potential difference applied to the third cathode 9, which maintains zero, it collides with the surface of the sample 10 with high energy.
In the crossed field discharge used in the present invention, a sufficient amount of primary ions incident on the surface of the sample can be obtained with a low working gas pressure, and the energy of the primary ions is high, so a large amount of surface material is spattered from the sample surface. Therefore, the present invention does not require differential pumping for primary ion irradiation, and the surface analysis apparatus can be made smaller and simpler.

In conventional secondary ion mass spectrometry, the neutral atoms that make up most of the sputtered particles cannot be used, and only a small amount of secondary ions are used, so it is difficult to detect secondary ions. This required special, highly sensitive measurement equipment. The present invention utilizes nearly all neutral atoms in the sputtered particles. Neutral atoms released from the sample surface upon ion bombardment move in the electron group of the crossed field discharge, and a portion of them is ionized and passes through the through hole 6 of the first cathode. The ion velocity selection device 13 applies a voltage between conductor plates and guides only ions with a predetermined velocity to the ion detection device 14. Since the ions that have passed through the through hole 6 of the first cathode and reached the entrance hole of the ion velocity selection device 13 have a certain amount of energy, their mass can be determined based on their velocity. That is, by changing the voltage between the conductor plates of the ion velocity selection device 13 and obtaining a correspondence with the ion current detected by the ion detection device 14, the surface of the sample 10 can be analyzed. The electron group of the crossed field discharge efficiently ionizes the neutral atoms sputtered from the sample 10, so the ion current detected by the ion detection device 14 is much larger than that of the conventional surface analysis device, and a special There is no need to use highly sensitive measuring equipment.

[Other embodiments of the invention]

The working gas may be introduced from anywhere, for example from the terminal 12. The magnetic field generator does not have to be the air-core coil shown in the embodiment. Ion mass spectrometry does not need to be performed using the rate selection method shown in the examples.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the main parts of a surface analysis device showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of the main parts of the present invention. 1... Vacuum container, 2... Vacuum device port, 3
... anode, 4 ... hollow part of anode, 5 ... first cathode, 6 ... through hole in first cathode, 7 ... second cathode, 8 ... through hole in second cathode, 9...Third cathode, 10...Sample, 16...Coil, 17,1
8,19...Power supply.

Claims (1)

[Claims] 1. An anode which is housed in a vacuum container to which a magnetic field is applied, has a hollow part extending through it, and whose axis is arranged parallel to the magnetic field; a first cathode disposed close to the opening so as to cover the opening and having a through hole in the axial direction of the anode; and a second cathode disposed to cover this opening and having a through hole coaxial with the through hole provided in the first cathode, and inserted into the through hole of the second cathode at a distance. a third cathode that holds a sample to be analyzed facing the anode, and an ion mass spectrometer that analyzes the mass of ions, which is provided spaced apart from and close to the through hole of the first cathode. A surface analysis device comprising: a means for applying the highest potential to the anode; and a means for applying a potential higher than each of the first and third cathodes to the second cathode.