JPH0351881Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is used in surface analysis devices using X-ray excitation such as photoelectron spectroscopy (ESCA or XPS) devices, X-ray microscopes, or X-ray lithography. X
It's about line guns.

(Prior Art) Conventional surface analysis devices using X-ray excitation do not have a structure that narrows down the X-ray beam irradiated onto a sample. Therefore, the sample is excited over an area several millimeters in diameter, and surface analysis obtains average information over that wide excitation area.

In order to perform surface analysis of a minute area of a sample,
It is necessary to narrow down the X-ray beam irradiated to the sample.
A zone plate (Fresnel zone plate) is known as an element that has a lens effect on X-rays.

(Problem to be solved by the invention) This zone plate can be used to
If we want to narrow down the line beam, we can consider the following, for example.

The first X-ray gun, as shown in FIG. The zone plate 10 condenses light as a primary light source (referred to as a primary light source), and a reduced image thereof is irradiated onto the sample 12.

However, this X-ray gun requires a large scale, and there is a problem that the smaller the primary light source on the anode 2 is made in order to make the X-ray image smaller, the more damage the anode 2 receives.

A second possible X-ray gun using zone plates is shown in FIG.
A cylindrical Wehnelt 14 is provided along the side wall of the anode 2, and a filament 16 is provided in a ring shape on the outside of the Wehnelt 14, and thermionic electrons 17 generated from the filament 16 are transferred to the anode 2. A repeller 18 is provided so as to form an electric field to guide the end face. Wehnelt 14, filament 16
The shape and position of the repeller 18 are the same as the filament 1.
The setting is such that the thermoelectrons 17 from the anode 6 are concentrated at one point on the end face of the anode 2. Then, the image of the characteristic X-rays 8 on the anode 2 is used as a primary light source and is focused by the zone plate 10 as in FIG. 3, and the reduced image thereof is irradiated onto the sample 12.

This X-ray gun has a problem in that it is difficult to create a uniform point light source on the anode 2, and therefore it is also difficult to form a reduced image on the sample 12.

Another possible X-ray gun using a zone plate is one that uses synchrotron radiation as the source. Since a parallel X-ray beam is obtained in synchrotron radiation, it is easy to obtain a reduced image using a zone plate, but a synchrotron radiation apparatus is too large-scale and thus is impractical.

X-ray guns that can emit a finely focused X-ray beam are used not only for analyzing minute areas in surface analyzers, but also for obtaining high resolution in X-ray microscopes, and in X-ray lithography. It is also required when forming fine patterns.

The object of this invention is to provide an X-ray gun that can emit an X-ray beam with a minute diameter without using large-scale equipment.

(Means for Solving the Problems) The X-ray gun of this invention is shown with reference to FIG. 1 showing an embodiment. Thermionic 22
filament 20 that emits and filament 2
means (Wehnelt 14, repeller 26) for forming an electric field so as to guide the thermoelectrons 22 emitted from the anode 2 to the anode 2; A plate-like member 32 having a small hole 30 for extracting the rays, and a characteristic X-ray 3 that passes through the small hole 30 of the plate-like member 32 to form an image.
The zone plate 10 is arranged on the axis of the zone plate 4.

(Function) The thermoelectrons 22 generated from the filament 20 are
The end face 28 of the anode 2 due to the electric field formed by the anode 2, Wehnelt 14, and the repeller
and collides with its end face 28 to generate characteristic X-rays. End surface (electron irradiation surface) 2 of this anode 2
The image of the characteristic X-ray 34 as a primary light source on 8 is
Like the conventional X-ray gun shown in FIG. 4, the diameter may be, for example, several millimeters. When the characteristic X-rays 34 pass through the small hole 30 of the plate member 32, the image of the small hole 30 becomes a secondary light source of the characteristic X-rays 34. The zone plate 10 uses the image of the small hole 30 of the characteristic X-ray 34 as a secondary light source, and forms this secondary light source image onto the sample 12.

Now, the distance between the zone plate 10 and the sample 12 is a, the distance between the zone plate 10 and the small hole 30 is b, and the distance between the zone plate 1 and the generated characteristic X-rays is
When the plate member 32, zone plate 10, and sample 12 are arranged so that the focal length of 0 is f, 1/a+1/b=1/f (1), the image of the small hole 30 will be the same as that of the sample. 12 at a reduction ratio of a/b.

(Example) FIG. 1 shows an embodiment of this invention.

2 is an anode, and a filament 20 is provided on the side of the anode 2 via a cylindrical Wehnelt 14. As is conventionally done, the filament 20 is optically blocked by the Wehnelt 14 and placed in a position where it cannot be seen from the anode 2. A repeller 26 is provided so as to surround the anode 2, the Wehnelt 14, and the filament 20. The potential of each part is set, for example, to several volts for the filament 20, several kilovolts for the anode 2, and to ground potential for the Wehnelt 14 and repeller 26.
Due to this potential difference, thermionic electrons 22 generated from the filament 20 collide with the end surface 28 of the anode 2, and characteristic X-rays 34 are generated.

The repeller 26 is the end surface of the anode 2 (electron irradiation surface)
A hole is provided in a portion facing the repeller 28, and a plate member 32 having a small hole 30 for extracting characteristic X-rays 34 is attached to the portion of the repeller 26 where the hole is located. The material of the plate member 32 is preferably molybdenum, tantalum, or tungsten, which have high heat resistance. The distance c between the plate member 32 and the end surface 28 of the anode 2 is set small.

Characteristic X-rays 3 passing through the small hole 30 of the plate member 32
4, a zone plate 10 is provided at a distance b from the small hole 30. The focal length f of the zone plate 10 is determined by the wavelength of the characteristic X-ray 34.

The sample 12 is placed at a distance a from the zone plate 10. The plate-shaped member 32, the zone plate 10, and the sample 12 are arranged between these distances a and b and the focal length f of the zone plate 10 so that the relationship of the above-mentioned equation (1) is established.

As an example, zirconium was used for the anode 2. At this time, the wavelength of the characteristic X-ray 34 is 82 Å. The diameter of the small hole 30 of the plate member 32 is 200 μm, and the distances a, b, and c of each member are 65 mm, respectively.
It was set to 322mm and 6mm. The effective diameter of the zone plate 10 was 2 mm, and the focal length f of the zone plate 10 for characteristic X-rays 34 having a wavelength of 82 Å was 54 mm. Under these conditions, a soft X-ray beam with a diameter of 40 μm was obtained on the sample 12.

If an attempt is made to increase the intensity of the characteristic X-rays 34, the anode 2 will become hot, so it is desirable to provide a cooling means for the anode 2. Alternatively, the anode may be a rotatable anode 40 as shown in FIG.
In addition, by moving the electron irradiation position 42 from the center of rotation, the electron irradiation position 42 may be moved as the anode 40 rotates.

Further, if a ring-shaped filament 16 as shown in FIG. 4 is used as the filament, it is effective in terms of the intensity of the generated characteristic X-rays 34.

(Effect of the invention) The X-ray gun of this invention has a small hole arranged opposite to the electron irradiation surface of the anode, uses the characteristic X-ray image from the small hole as a secondary light source, and uses a zone plate to Since the light source is configured to form an image on the sample, a small area of the sample can be irradiated with X-rays without using a large-scale device such as synchrotron radiation. This makes it possible to
This will enable ESCA analysis, X-ray microscopy, and X-ray lithography.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing one embodiment of this invention, Fig. 2 is a plan view showing the anode end face of another embodiment, and Fig. 3 shows a conventional X-ray gun combined with a zone plate. The side view and FIG. 4 are schematic cross-sectional views showing a state in which a zone plate is combined with another conventional X-ray gun. 2... Anode, 10... Zone plate, 1
4...Wehnelt, 20...Filament, 2
6...Repeller, 30...Small hole, 32...Plate member.

Claims (1)

[Claims for Utility Model Registration] An anode; a filament provided in close proximity to the anode that emits thermionic electrons that are irradiated to the anode; a plate-shaped member provided opposite to and close to the electron irradiation surface of the anode and having a small hole for extracting characteristic X-rays generated from the anode; an X-ray gun, comprising: a zone plate disposed on the axis of characteristic X-rays so as to image the characteristic X-rays;