JP2003131000A - Projection type x-ray microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray microscope easily usable in a laboratory level and having a high resolution. SOLUTION: A projection type X-ray microscope generates X-ray by irradiating electron beam to an X-ray target, casts the generated X-ray on the specimen and photographs an X-ray transmission image of specimen. The X-ray target consists of a light element film and a metal piece fixed on the light element film. By irradiating electron beam on the metal piece constituting the X-ray target, an X-ray is generated from the region of diameter of tens nm below the metal piece.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION The invention of this application is a projection type X
It relates to a line microscope. More specifically, the invention of this application relates to a projection X-ray microscope useful for observing a living body or an electronic material with high resolution of micro-order or nano-order.

[0002]

2. Description of the Related Art The development of an X-ray microscope having a large penetrating power, a short wavelength and a high resolution has been actively developed since the 1950s. But X
Due to its optical characteristics, it is not possible to apply a simple lens that uses refraction to the line, and even now, it has not been put to practical use like optical microscopes and electron microscopes that are commonly used. is the current situation.

Up to now, an X-ray microscope has been developed which realizes a resolution of about 20 nm by using a zone plate which is a lens utilizing a diffraction phenomenon. In this X-ray microscope, since the efficiency of the lens is low,
An extremely powerful X-ray source such as synchrotron radiation is required, and it has become a special microscope device with low versatility.

With the recent development of nanotechnology and biotechnology, there is a demand for easy observation of micro-order or nano-order structures such as semiconductor nondestructive inspection and protein or chromosome structure analysis. It is rising. In an optical microscope, it is impossible to observe a structure in a micro-order or a nano-order because of insufficient resolution, and in an electron microscope, it is difficult to observe a semiconductor or a chromosome due to insufficient penetrating power. Therefore, there is a demand for the development of an X-ray microscope which can be easily used at the laboratory level and has high resolution.

Conventionally, as a method for improving the intensity of X-ray generated from an X-ray source, a method using a rotating anticathode and a method of inserting a fine wire on an electron orbit of a synchrotron are widely known. In the former, heat generation is suppressed by rotating the target, and the intensity of X-rays is increased by narrowing the electron beam. But in this way,
There is a limit to the improvement of X-ray intensity due to the limitation due to the space electrification effect. In the latter case, the X-ray intensity is improved by making the target a thin wire. However, there is a mechanical limit when making a fine wire, and there is a problem that the target evaporates due to heat when the wire is made too thin.

The invention of Japanese Patent Laid-Open No. 2001-216927 is known as a proposal relating to an X-ray source for generating X-rays with high intensity while suppressing heat generation of a target, which is a problem with the above method. In the present invention, an X-ray target is composed of a spherical or rod-shaped target and a target support member made of a light element. And the target is
Supported by a target support member, or
It is characterized in that it is embedded inside the target support member, and realizes generation of X-rays with high intensity while suppressing heat generation of the target.

In order to improve the resolution of the X-ray microscope, it is necessary to reduce the area of the X-ray generation region in the X-ray target. In the conventional X-ray target, as shown in FIG. 5, even if the diameter of the electron beam is narrowed, the electron beam is scattered inside the metal, which is the X-ray target, so that the X-ray target emits X-rays. The area where is generated will be expanded. Therefore, in an X-ray microscope using a conventional X-ray source, the resolution is 0.1 μm.
It was difficult to do the following.

Therefore, the invention of this application was made in view of the above circumstances, and it is an object of the invention to provide an X-ray microscope which can be easily used at a laboratory level and has a high resolution. It is an issue.

[0009]

In order to solve the above-mentioned problems, the invention of the present application is as follows.
In a projection X-ray microscope that generates X-rays by irradiating a X-ray target, projects the generated X-rays on a sample, and captures an X-ray transmission image of the sample, the X-ray target is a light element film and a light element film. It is composed of a metal piece fixed on the top, and by irradiating an electron beam above the metal piece forming the X-ray target, X-rays are generated from a region having a diameter of several tens nm below the metal piece. A projection type X-ray microscope is provided.

In the projection X-ray microscope according to the invention of this application, secondly, the metal piece forming the X-ray target is cylindrical or spherical, and thirdly, the metal piece forming the X-ray target. The piece has a cylindrical shape having a diameter of 20 to 200 nm and a height of 20 to 200 nm, or a spherical shape having a diameter of 20 to 200 nm, and fourth, a metal piece constituting the X-ray target, A metal having an atomic number of 60 or more is selected, fifthly, the thickness of the light element film constituting the X-ray target is set to 20 to 200 nm, and sixthly, a light element film constituting the X-ray target. Is a silicon nitride film or a diamond film.

In the invention of this application, a plurality of metal pieces are individually fixed on the light element film in the X-ray target of the projection X-ray microscope described above, and the electron beam is applied to any of the metal pieces. By selectively irradiating the X-rays with each other, the X-ray generation position is changed, the X-ray transmission image of the sample projected from each generation position is captured, and the three-dimensional structure of the sample is reconstructed from the parallax of two or more images. Configuring is provided as an aspect of the seventh invention.

Further, the invention of this application is, as an eighth aspect of the invention, a method of manufacturing an X-ray target for generating X-rays by irradiating an electron beam, which comprises an anodic oxidation method on a light element film or Also provided is a method for producing an X-ray target, which is characterized by producing an isolated metal cylinder by etching.

In the above X-ray target manufacturing method, ninthly, the diameter of the metal cylinder is 20 to 200 nm,
Further, the height is 20 to 200 nm, and tenthly,
The metal forming the cylinder is selected from metals having an atomic number of 60 or more. Eleventh, the thickness of the light element film is 20 to 2
The twelfth feature is that the light element film is a silicon nitride film or a diamond film, and the thirteenth feature is that the number of generated metal cylinders is plural.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the characteristics as described above, and the embodiments thereof will be described below.

FIG. 1 is a schematic diagram showing the configuration of a projection X-ray microscope according to the invention of this application. In the projection X-ray microscope of the invention of this application, the X-ray target (2) is irradiated with the electron beam (1) to generate X-rays (3). X-ray (3) generated from X-ray target (2)
Is irradiated on the sample (4). The X-ray (3) irradiated on the sample (4) projects an X-ray transmission image on the plane behind the sample (4). By capturing the X-ray transmission image by the image capturing means (5), the structure inside the sample can be observed.

The beam diameter of the electron beam (1) irradiated on the X-ray target (2) is narrowed down so as to be smaller than the diameter of the metal piece. As a means for narrowing down the electron beam (1), for example, an electron microscope (6) as a source of the electron beam may be used. Specifically, the beam diameter of the electron beam is narrowed down to several tens of nm or less.

Although the projection X-ray microscope according to the invention of this application has the above-mentioned configuration, since no lens is used in the X-ray optical system, complicated procedures such as optical axis adjustment and focusing are performed. Does not need In the projection X-ray microscope according to the invention of this application, the magnification of imaging is determined as R2 / R1 by the distance R1 between the X-ray source and the sample and the distance R2 between the X-ray source and the imaging means. For example, R1 is 0.1m
When m and R2 are 100 mm, it is possible to obtain an X-ray transmission image with a magnification of 1000 times.

Since X-rays have a deep depth of focus, they are suitable for observing the internal structure of an optically opaque sample having a thickness of about several millimeters. Also, like an electron microscope,
There is no need to install the sample in vacuum. In this projection X-ray microscope, the sample is placed in the air or He gas (7), so that it is possible to apply living cells or micro organisms as the sample.

In the projection X-ray microscope according to the invention of this application, as shown in FIG. 2, the X-ray target comprises a light element film (21) and a metal piece (22) fixed on the light element film.
Composed of and. By making the shape of the metal piece (22) forming the X-ray target cylindrical or spherical, the cross-sectional area of the metal piece (22) can be reduced, and as a result, the electron beam (23) was irradiated. In this case, the area of the region (24) where X-rays are generated can be reduced.

When the shape of the metal piece (22) is cylindrical, the diameter is 20 to 200 nm and the height is 20 to 200 n.
By setting it in the range of m, an X-ray microscope with nano-order resolution is realized. Similarly, when the shape of the metal piece (22) is spherical, the diameter is preferably set in the range of 20 to 200 nm.

As the kind of the metal piece (22), since the X-ray generation efficiency is proportional to the square of the atomic number of the metal piece,
A metal having a large atomic number is preferably selected, and specifically, a metal having an atomic number of 60 or more is preferably selected. Further, as the light element film (21) constituting the X-ray target, a light element film such as silicon nitride or diamond is selected, and the film thickness is preferably 20 to 200 nm, for example.

Further, in the projection X-ray microscope according to the invention of this application, a plurality of metal pieces may be fixed on the light element film of the X-ray target. The plurality of metal pieces are fixed so as to exist individually on the light element film. At this time, the generation position of X-rays can be changed by selectively irradiating one of the metal pieces with the electron beam. By changing the X-ray generation position, the imaging position changes in the X-ray transmission image of the acquired sample. It is possible to reconstruct the three-dimensional structure of the sample by the principle of stereo imaging by examining the shift (parallax) of the sample in two or more X-ray transmission images.

The X-ray target of the projection X-ray microscope according to the invention of this application is produced by applying an anodic oxidation method or etching to the light element film to form an isolated metal cylinder. It For example, as shown in FIG. 3, the metal film (32) formed on the light element film (31) is etched to form isolated cylinders (33). FIG. 4 is an electron microscope image of a cylinder having a diameter of 80 nm actually manufactured by the above procedure.

With the projection X-ray microscope according to the invention of this application, the internal structure of the chromosome of the cell, which was insufficient in resolution with an optical microscope and could not pass electrons with an electron microscope, was observed in a state containing water. It becomes possible to do. Further, since no large-scale equipment such as synchrotron radiation is used, an X-ray microscope can be used at the laboratory level and feedback is easy.

By using the microscope CT as the imaging means, it is possible to numerically capture the three-dimensional structure of the sample. Moreover, if a CCD camera is applied as the imaging means,
It is also possible to capture changes in the sample over time as moving images. Furthermore, by increasing the acceleration voltage of the electron beam and shortening the wavelength of X-rays, it becomes possible to apply to nondestructive inspection of semiconductor materials.

The configuration of the projection X-ray microscope according to the invention of this application is an example, and the present invention is not limited to the configuration described above, and it is considered that various details can be adopted. It goes without saying that it should be.

[0027]

As described in detail above, the invention of this application provides an X-ray microscope which can be easily used at the laboratory level and has a high resolution. The invention of this application is applied to research and development in the fields of life science and advanced materials engineering such as elucidation of minute biological structures such as nerve cell networks and chromosomes during cell division, and analysis of surface phenomena in functional material research. It is considered to be very useful, and its practical application is strongly expected.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a projection X-ray microscope according to the invention of this application.

FIG. 2 is a schematic diagram showing a configuration of an X-ray target of the projection X-ray microscope according to the invention of this application.

FIG. 3 is a schematic diagram showing an X-ray target manufactured by the method of manufacturing an X-ray target according to the invention of this application.

FIG. 4 is a diagram showing an electron microscope image of an X-ray target actually manufactured by the method of manufacturing an X-ray target according to the invention of this application.

FIG. 5 is a schematic diagram showing the principle of generation of X-rays by a conventional X-ray target.

[Explanation of symbols]

1 electron beam 2 X-ray target 3 X-ray 4 samples 5 Imaging means 6 electron microscope 7 Air or He gas 21 Light element film 22 metal pieces 23 electron beam 24 X-ray generation area 31 Light element film 32 metal film 33 cylinder

Claims (13)

[Claims] 1. A projection type X-ray microscope for generating an X-ray by irradiating an X-ray target with an electron beam, projecting the generated X-ray on a sample, and capturing an X-ray transmission image of the sample,
The X-ray target is composed of a light element film and a metal piece fixed on the light element film, and by irradiating an electron beam above the metal piece forming the X-ray target, the diameter below the metal piece is in the range of several tens nm. A projection type X-ray microscope characterized in that X-rays are generated from the area. 2. The projection X-ray microscope according to claim 1, wherein the metal piece forming the X-ray target is cylindrical or spherical. 3. The metal piece forming the X-ray target has a diameter of 20 to 200 nm and a height of 20 to 200 nm.
3. The projection X-ray microscope according to claim 1, wherein the projection X-ray microscope has a columnar shape or a spherical shape having a diameter of 20 to 200 nm. 4. The projection X-ray microscope according to claim 1, wherein the metal piece forming the X-ray target is selected from metals having an atomic number of 60 or more. 5. The light element film constituting the X-ray target has a film thickness of 20 to 200 nm.
A projection X-ray microscope according to any one of 4 to 4. 6. The projection type X-ray microscope according to claim 1, wherein the light element film forming the X-ray target is a silicon nitride film or a diamond film. 7. An X-ray generation position is obtained by separately fixing a plurality of metal pieces on a light element film in an X-ray target and selectively irradiating any one of the metal pieces with an electron beam. 7. The X-ray transmission image of the sample projected from each generation position is changed, and the three-dimensional structure of the sample is reconstructed from the parallax of two or more images. 7. Projection X-ray microscope. 8. A method for producing an X-ray target for generating X-rays by irradiating an electron beam, comprising applying an anodic oxidation method or etching to a light element film to form a metal on the light element film. A method for producing an X-ray target, which comprises producing a cylinder made of metal. 9. The diameter of the metal cylinder is 20 to 200 n.
9. The method for producing an X-ray target according to claim 8, wherein the height m is 20 to 200 nm. 10. The metal constituting a cylinder has an atomic number of 60.
9. The metal selected from the above is selected.
Alternatively, the method of manufacturing an X-ray target according to Item 9. 11. The method for producing an X-ray target according to claim 8, wherein the film thickness of the light element film is 20 to 200 nm. 12. The light element film is a silicon nitride film or a diamond film.
A method of manufacturing any X-ray target. 13. The X according to claim 8, wherein the number of metal cylinders to be generated is plural.
Method of manufacturing line target.