JP2889147B2 - Ion beam exit window of ion beam analyzer for atmospheric pressure measurement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Rutherford backscattering spectrometer for guiding a helium ion beam into a sample chamber at atmospheric pressure from a vacuum, irradiating the sample placed in the sample chamber with the helium ion beam, and subjecting the sample to the helium ion beam. (Ruther
It is provided in an ion beam analyzer for atmospheric pressure measurement that performs chemical composition analysis by ford Backscattering Spectroscopy), and is an ion beam analyzer for atmospheric pressure measurement that transmits a helium ion beam from the vacuum side to the atmospheric pressure side. It is about an exit window.

[0002]

2. Description of the Related Art As is well known, Rutherford backscattering spectroscopy (RBS) is an analytical technique for knowing a chemical composition at or near the surface of a sample or a change in composition in the depth direction of the sample using a high-energy ion beam. It is one of. That is, when ions of mass M ₁ are accelerated with energy E ₀ and irradiated on a solid composed of atoms of mass M ₂ ,
Elastic scattering at the surface. Then, the energy E of the incident ion bounced back by the elastic scattering is equal to the mass M _{2 of the} partner nucleus.
From the energy spectrum of the bounced scattered ions, the mass of the partner element can be estimated.
In particular, the use of ions scattered backward as scattered ions has the highest measurement resolution, and this is used as Rutherford backscattering spectroscopy.

[0003] In the chemical composition analysis of a sample by Rutherford backscattering spectroscopy, it is common to place the sample in a vacuum chamber for analysis. However, for a sample that deteriorates in a vacuum, a sample that dislikes oxygen, etc., the ion beam was introduced from the vacuum into the sample chamber at atmospheric pressure by an ion beam analyzer for measurement under atmospheric pressure and placed in the sample chamber. The sample is irradiated with an ion beam, and the sample is subjected to chemical composition analysis by Rutherford backscattering spectroscopy.

Conventionally, an ion beam analyzer for atmospheric pressure measurement using protons as an ion beam has been known as this type of device. In an ion beam analyzer for atmospheric pressure measurement using protons as this ion beam,
As an ion beam exit window for transmitting an ion beam due to protons from the vacuum side to the atmospheric pressure side, one made of a Kapton thin film which is an organic film, one made by depositing a gold thin film on the surface of an aluminum foil, or a stainless steel thin film There are things that consist of

[0005]

By the way, 1 to 3 Me
When analyzing the chemical composition of a sample by Rutherford backscattering spectroscopy using an ion beam in a normal energy range of about V, the mass number between a light element and a heavy element such as iron, zinc, lanthanum, etc. Is a kind of borosilicate glass to which an intermediate element is added, it is necessary to use a helium ion beam having a high element (mass) discrimination ability instead of a proton in order to identify these elements.

When a helium ion beam having a normal energy of about 1 to 3 MeV is introduced from a vacuum to irradiate a sample placed in a sample chamber with a helium ion beam, an ion beam exit window is formed by the aforementioned Kapton thin film. If it is made of a thin film made of stainless steel or a thin film made of gold deposited on the surface of an aluminum foil, the helium ion beam is too thick, and the energy loss is large because it is difficult for the helium ion beam to pass through the ion beam exit window. Therefore, there is a problem that the chemical composition analysis by Rutherford backscattering spectroscopy cannot be sufficiently performed.

In view of the above, the present invention introduces a helium ion beam from a vacuum into a sample chamber at atmospheric pressure, irradiates a sample placed in the sample chamber with a helium ion beam, and subjects the sample to chemical analysis by Rutherford backscattering spectroscopy. An ion beam exit window for transmitting a helium ion beam from the vacuum side to the atmospheric pressure side, which is provided in an ion beam analyzer for atmospheric pressure measurement for performing composition analysis,
The helium ion beam can be transmitted with low energy loss and the vacuum is not broken, and the mass number between the light element such as carbon and the heavy element gold is an intermediate element. An object of the present invention is to provide an ion beam exit window of an ion beam analyzer for atmospheric pressure measurement capable of performing chemical composition analysis.

[0008]

In order to achieve the above object, an ion beam exit window of an ion beam analyzer for atmospheric pressure measurement according to the invention of claim 1 has a helium ion window in a sample chamber at atmospheric pressure. A beam is introduced from a vacuum, a sample placed in the sample chamber is irradiated with a helium ion beam, and the sample is provided with an ion beam analyzer for atmospheric pressure measurement for performing chemical composition analysis by Rutherford backscattering spectroscopy. An ion beam exit window for transmitting an ion beam from the vacuum side to the atmospheric pressure side. A gold thin film as an ion beam transmitting film is formed on a net made of one light element selected from beryllium, boron, and carbon. It is characterized by being attached.

The ion beam exit window of the ion beam analyzer for atmospheric pressure measurement according to the second aspect of the present invention is a device for guiding a helium ion beam from a vacuum into a sample chamber at atmospheric pressure and placing the sample in the sample chamber. Is equipped with an ion beam analyzer for atmospheric pressure measurement that irradiates the sample with a helium ion beam and performs chemical composition analysis on the sample by Rutherford backscattering spectroscopy. The ion is used to transmit the helium ion beam from the vacuum side to the atmospheric pressure side. It is characterized in that a gold thin film is adhered as an ion beam transmitting film to a beam exit window in which a surface of a net made of metal is coated with carbon.

[0010]

According to the first aspect, the ion beam exit window is 1 to 3 Me.
An ion beam transmitting film is formed by a thin gold film having a thickness capable of transmitting a helium ion beam having a normal energy of about V, and the gold thin film alone has insufficient strength to prevent a vacuum from being broken. In order to reinforce the structure, a mesh (mesh) made of a light element such as beryllium is used as a reinforcing material, and the gold thin film is attached to the mesh made of the light element. Accordingly, the helium ion beam can be transmitted with a small energy loss, and has a strength that does not break the vacuum. Since the beam diameter of the helium ion beam is about 1 mm, the size of the beam transmitting portion of the ion beam exit window is about 1.5 mm in diameter.

The thickness of the gold thin film is preferably 200 to 300 nm. If the thickness of the gold thin film exceeds 300 nm, energy loss at the time of transmission of the helium ion beam increases, and if the thickness is less than 200 nm, the thin film is easily damaged. The size of the mesh of the mesh is 150 to 25.
It is preferably 0 mesh. If the mesh size of the mesh exceeds 250 mesh, the aperture ratio becomes small and the signal intensity from the sample decreases, and if it is less than 150 mesh, the reinforcing effect becomes small.

It is preferable that the signal of the element constituting the sample and the signal from the ion beam exit window do not overlap on the spectrum of the RBS measurement. Since the ion beam transmitting film is made of a thin film of gold, which is a heavy element, and the mesh is made of one kind of light element selected from beryllium, boron, and carbon, the light beam of beryllium or the like is used. Chemical composition analysis can be performed on a sample containing an element whose mass number is intermediate between the element and the heavy element gold (eg, iron, zinc, silicon, and the like).

The ion beam exit window according to claim 2, further comprising a net made of metal instead of the net made of light elements, has a thickness capable of transmitting a helium ion beam having a normal energy of about 1 to 3 MeV. Since the ion beam transmitting film is constituted by the gold thin film, the strength of the gold thin film alone is insufficient to prevent the vacuum from being broken, so that a reinforcing member made of a metal to reinforce the gold thin film is used as a reinforcing material. It is obtained by attaching the above-mentioned gold thin film to a net-like body having carbon coated on its surface. Accordingly, the helium ion beam can be transmitted with a small energy loss, and has a strength that does not break the vacuum.

[0014] As in the first aspect, the gold thin film preferably has a thickness of 200 to 300 nm.
The mesh size of the mesh is preferably 150 to 250 mesh. As a material for forming the network, a material which can be easily coated with carbon is preferable, and for example, molybdenum can be mentioned.
It is preferable that the thickness of the carbon coating layer coated on the surface of the network is set so that the helium ion beam hitting the carbon coating layer stops in the carbon coating layer.

Further, as in the case of the first aspect, it is preferable that the signal of the element constituting the sample and the signal from the ion beam exit window do not overlap on the spectrum of the RBS measurement. Since the ion beam transmitting film is composed of a thin film of gold, which is a heavy element, and the surface of a mesh made of metal is coated with carbon, the mass number between carbon, which is a light element, and gold, which is a heavy element, is large. Chemical composition analysis can be performed on samples containing intermediate elements (eg, iron, zinc, silicon, etc.).

[0016]

Embodiments of the present invention will be described below.
FIG. 1 is a structural explanatory view showing a main part of an ion beam analyzer for atmospheric pressure measurement provided with an ion beam exit window according to the present invention.

In FIG. 1, reference numeral 51 denotes a beam line tube. The beam line tube 51 is connected to a beam extraction unit 52 provided with an ion beam exit window 1 described below at the tip, and the inside of the beam line tube 51 and the beam extraction unit 52 is maintained at a predetermined degree of vacuum. It has become so. An annular type scattered ion detecting semiconductor detector (annular SSD, hereinafter simply referred to as an annular type scattered ion detector) 53 is provided at a position opposite to the ion beam exit window 1 in the beam extraction unit 52. . S is a sample. The sample S is placed in a sample chamber (glove box) (not shown) filled with helium gas at atmospheric pressure. The helium ion beam having an energy of about 1 to 3 MeV passes through the central opening of the annular scattered ion detector 53 from the beam line tube 51 and enters the beam extraction unit 52, and passes through the ion beam exit window 1 described later. The sample S is transmitted and radiated to the sample S arranged in the atmospheric pressure. Then, the scattered ions from the sample S are detected by the annular scattered ion detector 53, and the chemical composition analysis of the sample S by Rutherford backscattering spectroscopy is performed.

FIG. 2 is a schematic sectional view of an ion beam exit window showing one embodiment of the present invention provided in the ion beam analyzer for atmospheric pressure measurement shown in FIG. 1, and FIG. 3 is a view of the ion beam exit window of FIG. FIG.

2 and 3, reference numeral 11 denotes a molybdenum net made of molybdenum having a mesh size of 200 mesh, and reference numeral 12 denotes a carbon coating layer coated on the surface of the molybdenum net 11. A phase synthetic diamond coating layer, 13 is a thin gold film having a thickness of about 250 nm, and 14 is an adhesive (araldite). This ion beam exit window 1
Forms a vapor-phase synthetic diamond coating layer 12 on the surface of a molybdenum net 11 and forms the molybdenum net 11
On the surface opposite to the vapor-phase synthetic diamond coating layer 12 of
A gold thin film 13 is bonded as an ion beam transmitting film with an adhesive 14. Reference numeral 54 denotes a graphite outlet window support member fixed to the tip of the beam extraction unit 52, which has a thickness of about 1 mm, and has an opening with a diameter of 1.5 mm at the center where a helium ion beam is incident. I have. The ion beam exit window 1 has an exit window support member 5 with the gold thin film 13 side positioned on the atmospheric pressure side.
4 is fixed to the opening portion by an adhesive 14.

The molybdenum net 11 has a thickness of about 15 μm, and in this embodiment, it is used for electron microscopy, that is, when observing a thin sample through which a beam is transmitted when observing the sample with an electron microscope. A sample mounting plate having a diameter of 3 mm which is generally used as a sample mounting plate for mounting the thin sample was used. The molybdenum net 11 is not formed by braiding a metal wire (molybdenum wire), but is formed in a planar shape such as a punched plate (a perforated plate).

On the surface of the net 11 made of molybdenum, a vapor-phase synthetic diamond coating layer 12 having a thickness of about 2 μm was formed. This formation is performed by using a microwave CVD (chemical vapor deposition) apparatus, placing the molybdenum net 11 on a substrate holder in a reaction chamber of the apparatus, and adding hydrogen gas (a small amount of oxygen is added). A raw material gas obtained by mixing methane and methane gas was introduced into a reaction chamber (degree of vacuum: 40 Torr), and the reaction was performed at a substrate holder temperature of 800 ° C. and a synthesis time of about 7 hours.

Next, the production of the gold thin film 13 will be described. First, on a mirror-polished glass plate, a thickness of about 200 nm is formed.
Was evaporated, and a gold thin film having a thickness of about 250 nm was evaporated on the aluminum thin film. Then, when an aqueous solution of NaOH is poured into the container containing this, only the aluminum thin film is dissolved, and the gold thin film floats on the water surface. The gold thin film floating on the surface of the aqueous solution is scooped with the molybdenum net 11 having the vapor-phase synthetic diamond coating layer 12 formed on one surface.

While the ion beam exit window 1 thus prepared is set in an ion beam analyzer for measurement under atmospheric pressure, a copper plate as a sample S is placed in a sample chamber which is at atmospheric pressure and is filled with helium gas. A helium ion beam having an energy of 2 MeV is transmitted through the ion beam exit window 1 and irradiated on the copper plate located at a position 5 mm away from the ion beam exit window 1 to form an annular scattered ion detector. An RBS measurement spectrum according to 53 was obtained. FIG. 4 shows the results. In FIG. 4, the horizontal axis is
The ratio of the rebounded helium ion energy E to the incident helium ion energy E ₀ is shown.
Indicates the number of helium ions bounced back. As can be understood from FIG. 4, in the ion beam exit window 1 of the ion beam analyzer for atmospheric pressure measurement according to the present invention, a helium ion beam is introduced from a vacuum into a sample chamber at atmospheric pressure and placed in the sample chamber. When the sample is irradiated with a helium ion beam and the sample is subjected to chemical composition analysis by Rutherford backscattering spectroscopy, the helium ion beam can be transmitted from the vacuum side to the atmospheric pressure side with a small energy loss and the vacuum It is possible to perform chemical composition analysis on a sample containing an element having an intermediate mass number between carbon as a light element and gold as a heavy element (for example, iron, zinc, silicon, etc.) without being broken. Recognize.

FIG. 5 is a schematic sectional view of an ion beam exit window showing another embodiment of the present invention provided in the ion beam analyzer for atmospheric pressure measurement shown in FIG. 1, and FIG. 6 is an ion beam exit window of FIG. FIG.

5 and 6, reference numeral 21 denotes a beryllium net having a mesh size of 200 mesh and made of beryllium; 23, a gold thin film having a thickness of about 250 nm;
4 is an adhesive (araldite). The ion beam exit window 2 is connected to a beryllium net 21 made of beryllium, which is a light element, by a gold thin film 2 as an ion beam transmitting film.
3 is adhered with an adhesive 24. The ion beam exit window 2 is fixed to the above-described opening portion of the exit window support member 54 made of graphite with the adhesive 24 in a state where the gold thin film 23 side is located on the atmospheric pressure side. Like the molybdenum net 11, the beryllium net 21 is not formed by knitting a metal wire (beryllium wire), but is formed in a planar shape such as a punched plate (perforated plate). The method of manufacturing the gold thin film 23 is the same as that of the gold thin film 13 described above.

In the ion beam exit window 2 of the ion beam analyzer for atmospheric pressure measurement configured as described above, a helium ion beam is introduced into the sample chamber at atmospheric pressure in the same manner as shown in FIG. The helium ion beam is irradiated from the vacuum side to the atmospheric pressure side with less energy loss when the sample placed in the sample chamber is irradiated with a helium ion beam and subjected to chemical composition analysis by Rutherford backscattering spectroscopy. A sample containing an element (eg, iron, zinc, silicon, etc.) having an intermediate mass number between beryllium, which is a light element, and gold, which is a heavy element, which can be permeated and does not break vacuum. Can be subjected to chemical composition analysis.

[0027]

As described above, in the ion beam exit window of the ion beam analyzer for atmospheric pressure measurement according to the first and second aspects of the present invention, a helium ion beam is introduced from a vacuum into a sample chamber at atmospheric pressure. When a sample placed in the sample chamber is irradiated with a helium ion beam and subjected to chemical composition analysis by Rutherford backscattering spectroscopy, the helium ion beam is transmitted from the vacuum side to the atmospheric pressure side with little energy loss. A chemical composition analysis can be performed on a sample containing an element having an intermediate mass number between a light element such as carbon and gold which is a heavy element without breaking vacuum.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a main part of an ion beam analyzer for atmospheric pressure measurement provided with an ion beam exit window according to the present invention.

FIG. 2 is a schematic cross-sectional view of an ion beam exit window showing one embodiment of the present invention provided in the ion beam analyzer for atmospheric pressure measurement shown in FIG.

FIG. 3 is a plan view of the ion beam exit window of FIG.

FIG. 4 is a diagram showing an example of an RBS measurement spectrum.

5 is a schematic sectional view of an ion beam exit window showing another embodiment of the present invention provided in the atmospheric pressure measurement ion beam analyzer shown in FIG. 1;

FIG. 6 is a plan view of the ion beam exit window of FIG.

[Explanation of symbols]

1, 2 ... Ion beam exit window 11 ... Molybdenum net 12: Vapor-phase synthetic diamond coating 13,23 ...
Gold thin films 14, 24 Adhesive 21 Beryllium netting 51 51 Beamline tube 52 Beam extraction unit 5
3: annular semiconductor detector for detecting scattered ions 54: support member for exit window S: sample

Continuation of the front page (72) Inventor Masayuki Inaba 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobelco Research Institute Co., Ltd. Seishin Office (72) Inventor Hirofumi Fukuyama 2-3-1 Niihama, Araimachi, Takasago-shi, Hyogo Prefecture No. Kobe Steel, Ltd. Takasago Works (56) References JP-A-9-43158 (JP, A) JP-A-3-257751 (JP, A) JP-A-1-77976 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 23/00-23/227 G21K 5/00 H01J 33/04 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A helium ion beam is introduced from a vacuum into a sample chamber at atmospheric pressure, and a sample placed in the sample chamber is irradiated with a helium ion beam to analyze a chemical composition of the sample by Rutherford backscattering spectroscopy. An ion beam exit window provided in an ion beam analyzer for measurement under atmospheric pressure for transmitting a helium ion beam from a vacuum side to an atmospheric pressure side. The ion beam exit window is selected from beryllium, boron, and carbon. An ion beam exit window of an ion beam analyzer for measurement under atmospheric pressure, characterized in that a gold thin film as an ion beam transmitting film is attached to a network made of elements. 2. A helium ion beam is introduced from a vacuum into a sample chamber at atmospheric pressure, and a sample placed in the sample chamber is irradiated with a helium ion beam to analyze a chemical composition of the sample by Rutherford backscattering spectroscopy. An ion beam exit window that is provided in an ion beam analyzer for atmospheric pressure measurement and that transmits a helium ion beam from the vacuum side to the atmospheric pressure side, the surface of a mesh made of metal coated with carbon An ion beam exit window of an ion beam analyzer for atmospheric pressure measurement, wherein a gold thin film is adhered as an ion beam transmitting film to the ion beam analyzer.