JP3384654B2 - Modification method of metal surface by gas cluster ion beam - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for modifying a metal surface by a gas cluster ion beam. More specifically, the present invention relates to modification of a metal surface by a gas cluster ion beam, which is useful for modifying a shallow layer portion of a metal surface to form a highly functional material having improved chemical or mechanical properties. It is about quality methods.

[0002]

2. Description of the Related Art Recently, as one of high-performance materials, attention has been paid to high-performance materials in which only the surface shallow layer portion is modified to improve its chemical or physical characteristics.
As a method of forming such a highly functional material in which only the surface shallow layer portion is modified, a method of irradiating the surface of the target material with an ion beam is known. A method of performing beam irradiation is also being studied.

However, in the method of irradiating the ion beam, although the very shallow surface layer of the target material can be modified depending on the accelerating voltage, the ion beam current amount generally decreases. It takes a very long time to obtain the required ion beam dose. Therefore, such a method is not necessarily an efficient method in the production process.

On the other hand, as a method for modifying the shallow surface layer of the target material, a method of equivalently reducing the energy of the constituent atoms by using a compound gas such as BF ₃ is considered. Although this method does not require a long time, the characteristics of the implanted F atoms and the like may have a very bad influence on the target material, and the atoms and the like along the crystal of the target material may be affected. However, there is a constraint that it is impossible to avoid the channeling phenomenon that is injected, and as a result, it is impossible to modify the surface of a very shallow surface layer of the target material.

In order to avoid such channeling effect, for example, a method of forming a thin oxide film on a target material and performing ion beam irradiation through the oxide film has been studied. In this case, the material of the oxide film actually penetrates into the target material, and it is not possible to expect the production of a high-purity and high-quality surface-modifying material. As described above, the surface modification in the shallow surface layer was difficult with the conventional technique, but it was even more difficult in the case of a material such as beryllium (Be) having a light mass and brittleness at room temperature. . For example, this beryllium is famous as a metal having the least X-ray transmission loss, and is widely and widely used as a thin film of an X-ray transmission window of an X-ray detection tube. At present, it is absolutely necessary to improve the X-ray detection sensitivity, for example, in connection with high octane and the problem of exhaust gas. For that purpose, the beryllium thin film is further thinned to increase the X-ray transmittance. Is needed. However, the beryllium thin film used for the X-ray transmission window often comes into direct contact with water, alcohol, etc., and the beryllium thin film is corroded by the water content or alcohol, and in the worst case, perforation occurs in the beryllium thin film. In some cases, due to such circumstances, it is practically impossible to form a thin film of beryllium.

In order to prevent perforation of the beryllium thin film, it has been studied to form beryllium oxide having a high density on the surface of the beryllium thin film, but since the beryllium thin film is very thin, conventional ion The beam surface modification method has a serious problem that the beryllium thin film is perforated during the modification.

The present invention has been made in view of the above circumstances, and even when targeting beryllium or the like, surface modification is performed only in a very shallow surface layer portion of the surface shallow surface layer. It is an object of the present invention to provide a surface modification method capable of providing a highly functional metal material having improved chemical or physical properties of a layer portion.

[0008]

SUMMARY OF THE INVENTION The present invention, as to solve the above problem, the oxygen and gas composed of a set of gaseous atoms or molecules at normal temperature and pressure comprising one or more oxygenates clusters the irradiated to ionize to form gas-cluster ion beam metal surface, the metal by the gas cluster ion beam, and forming a metal atom is oxidized metal oxide surface shallow layer portion of the metal A method of modifying a surface is provided.

That is, the present invention is characterized in that the surface modification of only the shallow surface layer portion is performed by using the gas cluster ion beam. This means that the gas cluster ion beam is capable of low energy irradiation with an extremely high density as compared with conventional monatomic or molecular ions, and as a result, it has high surface reactivity that cannot be expected with conventional ion beams. It is based on a new finding found by the inventor of the present invention that it is expressed only in the shallow layer portion and enables high density modification of the target material at a very shallow surface layer portion at a temperature around room temperature. .

In fact, by irradiation with gas cluster ions, an oxide layer, a nitride layer, a carbonized layer, etc. can be formed in a very shallow surface layer of tens to hundreds of nanometers of the target material. In this invention, from such a thing,
By controlling the amount of ions to be irradiated and physical factors such as energy, a gaseous substance selected from the group of oxygen, oxygen-containing compounds, nitrogen, nitrogen-containing compounds, and carbon compounds at room temperature and atmospheric pressure is selected. Two or more kinds of gas cluster ion beams formed by ionizing a gas cluster composed of an assembly of atoms or molecules are alternately or simultaneously irradiated to the metal surface to form two or more kinds of oxides, nitrides and carbides. Provided is a method for modifying a metal surface by a gas cluster ion beam, which is characterized by forming a gradient composition having a composite composition.

That is, according to the method of the present invention, it is possible to adjust the degree of the gradient function, and it is possible to create a highly functional material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as described above, by using a gas cluster ion beam, it is possible to perform irradiation with low energy at an extremely high density as compared with conventional monatomic ion beams and molecular ion beams. It realizes selective modification of the surface shallow layer portion of a metal material, and enables formation of an oxide layer or a graded composition of oxide, nitride, or carbide.

The target metal is not particularly limited, and various metals such as the above-mentioned beryllium (Be) having a light mass and exhibiting brittleness at room temperature, and other metals such as Al, Ti,
Zr, Cu, Cd, Ag, Ta, Hf, V, Ma, N
b, W, Sb, Bi, Ni, Co, Fe, Y, Ce, S
m and other various rare earth metals. In the present invention, these metals are targeted for O ₂ , CO, CO ₂ , HCHO, CH ₃ OH, which are gaseous at room temperature and atmospheric pressure.
Ions of oxygen, oxygen-containing compounds, nitrogen, nitrogen-containing compounds, and carbon compound gas clusters such as N ₂ , NH ₃ , NOx, and CH ₃ NH ₂ are used. In this case, the formation of gas clusters and their ionization are described. The method already proposed by the present inventor, for example, a method of generating clusters by ejecting a compressed gas from an expansion nozzle and ionizing them by electron beam irradiation, etc. are appropriately adopted.

The size of the gas cluster, that is, the size of the aggregate of atoms or molecules is also controlled by the gas pressure, the temperature at the time of jetting, and the like. For a gas with a low liquefaction temperature such as O ₂ , gas nozzles facilitate the formation of gas clusters. The cluster size can be adjusted, for example, by hundreds to tens of thousands. By irradiating the surface with these gas cluster ions, it becomes possible to form a selective oxide layer, a graded composition layer, etc. in the shallow surface layer of the metal material.

The present invention will be described in more detail below with reference to examples.

[0016]

EXAMPLES Example 1 A CO ₂ cluster ion beam having a cluster size of 1000 to 3000 was generated by jetting CO ₂ compressed gas from an expansion nozzle, and an accelerating voltage of 20 kV and an irradiation ion current of 10 ⁵ / cm ² were used. The surface of the titanium thin plate previously washed with the organic solution was irradiated with a CO ₂ cluster ion beam.

The relationship between the retarding voltage and the ion current at this time is as shown in FIG. 1, and the size distribution of the cluster ion beam when irradiated with cluster ions with an accelerating voltage of 20 kV at room temperature is as follows. It was as shown in FIG. A few seconds after the CO ₂ cluster ion beam irradiation, the irradiation was terminated, and the titanium thin film surface was analyzed using photoelectron spectroscopy. FIG. 3 shows the standard spectrum which is the result. From this result, 45
A signal with a binding energy of 8.5 eV was obtained,
It was confirmed that TiO ₂ was produced in a very shallow surface layer of tens to hundreds of nanometers on the surface of this titanium thin film. Example 2 At room temperature, the beryllium thin film surface was irradiated with cluster ions of CO ₂ gas to form beryllium oxide on the beryllium surface. The conditions were the same as in Example 1 above. The standard spectrum of the beryllium thin film surface by photoelectron spectroscopy was as shown in FIG.

From this FIG. 4, it was confirmed that the beryllium thin film was formed with high-density beryllium oxide within a range of several tens of nanometers from the surface thereof.

[0019]

As described in detail above, according to the present invention, it is possible to selectively modify the surface layer of a metal material to provide a highly functional material having improved chemical or physical properties. Is possible. In particular, it becomes possible to form an oxide substance having a high density in a very shallow surface layer portion of a brittle material such as a beryllium thin film, so that it is possible to provide an X-ray detector having high sensitivity.

It is also possible to provide a highly functional gradient composition material having a composite composition of at least two kinds of materials such as oxides, nitrides and carbides in the shallow surface layer.

[Brief description of drawings]

FIG. 1 is a relationship diagram showing a relationship between retarding voltage and ion current in Example 1.

FIG. 2 is a relationship diagram showing a relationship between a cluster size and a differential spectrum in Example 1.

FIG. 3 is a standard spectrum diagram of a titanium oxide surface in Example 1.

FIG. 4 is a standard spectrum diagram of a beryllium oxide surface in Example 2.

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Claims (2)

(57) [Claims] 1. A oxygen and gaseous atoms or gas cluster ion beam gas cluster of the set formed by ionization of molecules at normal temperature and pressure comprising one or more oxygenates irradiating the metal surface Te, of the metal
A method for modifying a metal surface by a gas cluster ion beam, which comprises forming a metal oxide by oxidizing metal atoms in a shallow surface layer . Wherein oxygen, oxygen-containing compounds, nitrogen, gas of the gas cluster ions consisting of the set of gaseous atoms or molecules in the selected normal temperature and pressure from the group of nitrogen-containing compound and a carbon compound formed by ionization A gas cluster characterized by irradiating a metal surface with two or more kinds of cluster ion beams, alternately or simultaneously, to form a graded composition composed of a composite composition of two or more kinds of oxides, nitrides and carbides. Method of modifying metal surface by ion beam.