JPH0355934B2 - - 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 widespread 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, because the yield of secondary ions used in secondary ion mass spectrometry (i.e., the number of secondary ions per primary ion) is very small, it is difficult to use secondary ion mass spectrometry with very high sensitivity. Requires measuring 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, a mass spectrometer that can function without the use of highly sensitive measurement equipment. Our goal is to provide the following. [Summary of the Invention] In order to achieve the above object, the present invention provides a vacuum container used in connection with a vacuum device having an exhaust device and a gas supply device, and an anode and two cathodes housed in the vacuum container. to form a secondary ion generating part that generates ions of the surface substance of the sample, the anode has a hollow part in the shape of a truncated cone, and the first A cathode, and a second cathode for large openings, are arranged to cover each opening, the first cathode is provided with a through hole coaxial with the hollow part of the anode, and the second cathode is provided with a through hole coaxial with the hollow part of the anode. The sample to be surface analyzed is placed on the cathode at the axis of the hollow part of the anode.
and means for applying a magnetic field substantially parallel to the inner surface of the anode in the hollow portion of the anode, the anode having a potential higher than the potential of the two cathodes, the first cathode having a second cathode; A secondary ion generator used for surface analysis was constructed by applying a potential not higher than the potential of the secondary ion generator. [Effects of the invention] A differential pumping system is not used because the sample is placed facing the discharge space and the intensity distribution of the magnetic field is suitable for the primary ions generated by the discharge to collide with the sample surface. The sample is irradiated with primary ions with high gas efficiency using a small and simple device, and the neutral atoms that make up most of the particles on the sputtered sample surface are removed using high-temperature, high-density particles that are confined in the secondary ion generator. By ionizing with a group of electrons and generating a large amount of secondary ions, there is no need to use highly sensitive measurement equipment to detect secondary ions. [Embodiment of the Invention] FIG. 1 is a longitudinal cross-sectional view of the main part of a surface analysis device showing an embodiment of the present invention. Reference numeral 1 denotes a vacuum container, which is connected to a port 2 of a vacuum device having an exhaust device and a gas supply device. 3 is an anode having a truncated conical hollow portion 4; 5 is a first anode having a through hole 6 coaxial with the hollow portion 4 of the anode; It is the shadow of A second cathode 7 is disposed so as to cover the large diameter opening of the hollow part 4 of the anode, and a part of the second cathode 7 is located at the axis of the hollow part 4 of the anode. A sample 8 whose surface is to be analyzed is held and placed in a holder 9. The holder 9 also serves as a power supply path from a terminal 10 to which a power output (not shown) is applied to the second cathode 7. The second cathode 7 is insulated from the vacuum vessel 1 and supported by a column 11 that is supported by a support portion (not shown) inside the port 2 . The first cathode 5 is supported by a column 12 supported by a support section inside the port 2, and is supplied with power via the column 12 from a power source (not shown). The anode 1 is supported by the grounded vacuum vessel 1 and is used at ground potential. Although the present invention does not impose any restrictions on the method of mass spectrometry of secondary ions, the 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. The ion velocity selection device 13 and the ion detection device 14 are
It has an electrically conductive path inside and is supported by a column 15 supported by the support portion of the port. The anode 3, the first cathode 5, the second cathode 7, the ion velocity selection device 13, and the ion detection device 14 are housed in the vacuum container 1. A coil 16 constitutes a magnetic field generator together with a power source (not shown). 16a is a coil wound uniformly, 16b is a coil whose number of turns is varied in the longitudinal direction, and the two coils 16a and 16b are the coil 1.
6 and is excited by a power supply (not shown), applies a magnetic field substantially parallel to the inner surface of the anode 3 throughout the hollow portion 4 of the anode, and ionizes the anode. Apply a substantially uniform magnetic field to the speed 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. The coil 16 is the second
Lines of magnetic force 17, which are not shown in the figure, indicate the magnetic field created by the magnetic field.
is shown in Figure 2. The anode 3 is grounded, and the second cathode 7 is given a negative potential by a power source 18. A lower potential than the second cathode 7 is applied to the first cathode 5 by power supplies 18 and 19. 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 is supplied to the hollow part 4 of the anode. reach In the hollow part 4 of the anode, a type of PIG discharge is generated and sustained by the applied magnetic field and the electric field created by the interelectrode voltage. In order to safely sustain the discharge, the potential of the second cathode must not be higher than the potential of the second cathode. A group of high-temperature, high-density electrons is confined in the hollow part 4 of the anode, and ionizes gas molecules. Due to the force received from the electromagnetic field, ionized molecules (for example, argon atoms) move in the positive hollow part 4 as shown as a locus 20 in FIG. , and collides with the surface of the sample with a high probability. In the PIG 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, so the present invention does not require a differential pumping system for primary ion irradiation.
The surface analysis device can be made smaller and simpler. Conventional secondary ion mass spectrometry cannot utilize the neutral atoms that make up the majority of sputtered particles, and uses only a very small amount of secondary ions, so it is difficult to detect secondary ions. This required special high-density measurement equipment. In the present invention,
Almost all of the sputtered particles are neutral atoms. Neutral atoms released from the sample surface upon ion bombardment move in the electron group of the PIG discharge, and a part of them is ionized and passes through the through hole 6 of the first cathode. The ion velocity selection device 13 sets the voltage between the conductor plates and guides only ions with a predetermined velocity to the ion detection device 14. The ion velocity selector 13 passes through the through hole 6 of the first cathode.
Ions that reach the entrance hole have a certain amount of energy, so their mass can be determined by their velocity. That is, the surface of the sample 8 can be analyzed by changing the voltage between the conductor plates of the ion velocity selection device 13 and obtaining a correspondence with the ion current value detected by the ion detection device 14. Since the electron group of the PIG discharge efficiently ionizes the neutral atoms sputtered from the sample 8, the ion power source detected by the ion detector 14 is much larger than the ion power source of a conventional surface analyzer, and a special high-speed There is no need to use a sensitivity measuring device. [Embodiments of the Invention] The working gas may be introduced from anywhere, for example, the magnetic field generator which may be introduced from the terminal 10 does not have to be an air-core coil as shown in the embodiments. 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. DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Port of vacuum device, 3... Anode, 4... Hollow part of anode, 5... First cathode, 6... Through hole of first cathode, 7... Second cathode, 8... Sample ,
16...Coil, 18,19...Power supply.

Claims (1)

[Scope of Claims] 1. A vacuum container that is used in connection with a vacuum device having an exhaust device and that houses the following anode and two cathodes, an anode that has a truncated cone-shaped hollow part, and a hollow part of the anode. A first cathode is disposed so as to cover a small diameter opening in the anode and has a through hole coaxial with the hollow part of the anode, and a first cathode is disposed so as to cover a large diameter opening in the hollow part of the anode. a second cathode having a sample to be analyzed on the surface disposed at the axis of the hollow part of the anode; and means for applying a magnetic field substantially parallel to the inner surface of the anode to the hollow part of the anode. , means for applying a potential lower than the anode potential to the second cathode and not higher than the potential of the second cathode to the first cathode.