JPH0759943B2 - Spatula ion pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is a sputter ion pump that performs vacuum evacuation by the action of sputtered atoms. The vacuum container has a cylindrical shape, and the cathode and the anode arranged therein are annular. At the same time, by making the permanent magnet arranged outside the vacuum container into an annular shape and making the exhausted space near the center of the cylindrical vacuum container, it is possible to reduce the exhausted volume and increase the exhaust conductance at the same time. High vacuum can be realized with this device.

INDUSTRIAL FIELD OF APPLICATION The present invention is used for obtaining an oil-free high vacuum, and in particular, a vacuum exhaust pump for an electron gun in an electron beam apparatus (electron microscope, electron beam exposure apparatus, electron beam LSI tester, etc.). The present invention also relates to a sputter ion pump that can also be used as.

[Conventional technology]

A conventional sputter ion pump has, for example, two cathode electrodes and an anode electrode sandwiched between them in a rectangular vacuum container, and two permanent magnets are arranged so as to sandwich the vacuum container. It has a structure, and when it is used, it is connected to an exhausted container which is a separate body from this.

[Problems to be solved by the invention]

Generally, in order to increase the degree of vacuum of the sputter ion pump, (i) reduce the volume (surface area) of the exhausted container, and (ii) exhaust conductance (gas emission) between the sputter ion pump and the exhausted container. Ease of flow; [/ se
c)) needs to be raised. However, in the above-mentioned conventional sputter ion pump, in order to satisfy the condition of (i), the exhaust port communicating with the outside exhausted container must be made small in diameter, and if this is done, the exhaust conductance decreases and the above ( The condition of ii) cannot be met.
On the contrary, if the condition (ii) is to be satisfied, the condition (i) cannot be obtained this time. That is, it was very difficult to satisfy both the above conditions (i) and (ii) with the conventional sputter ion pump.

In view of the above problems, it is an object of the present invention to provide a sputter ion pump that can obtain a high vacuum with a small device.

[Means for solving problems]

In the sputter ion pump of the present invention, the vacuum container is formed into a cylindrical shape, the cathode electrode and the anode electrode are formed into an annular shape so as to be housed therein, and the permanent magnet outside the vacuum container is also formed into an annular shape corresponding to the shape of the electrode. In addition, the vicinity of the center of the cylindrical vacuum container is set as an exhausted space.

[Action]

In the vacuum container, gas molecules are ionized by cold cathode discharge in a magnetic field and trapped in the cathode electrode (ion pump action). Further, at this time, the cathode material is sputtered from the cathode electrode, whereby an active getter film is generated on the anode electrode and the like, and gas molecules are adsorbed by this getter film (chemical adsorption action).

In the present invention, such an exhaust action is a space surrounded by an annular element (cathode electrode, anode electrode) having a vacuum exhaust capability (that is, the exhausted space).
Done against. Therefore, even though the exhausted volume, which is the volume of the exhausted space, is small, it is possible to exhaust from the entire surroundings instead of through the exhaust port as in the conventional case,
Exhaust conductance can be increased. Therefore, the above conditions (i) and (ii) are both satisfied,
High vacuum can be realized with a small device.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional perspective view showing an embodiment of the present invention, and FIG. 2 is a vertical sectional view thereof.

In FIGS. 1 and 2, two cathode electrodes 2 and 3 made of an annular metal plate (for example, made of titanium) are arranged to face each other in a cylindrical vacuum container 1, and the cathode electrodes An annular anode electrode 4 is arranged so as to be sandwiched between the two. The anode electrode 4 is formed by annularly forming a so-called HOLE AND SLOT structure (see Japanese Patent No. 585335) in which a plurality of small cylinders 4a are connected. An anode high voltage introducing terminal 4b for introducing a high voltage to the anode electrode 4 extends outward from the side wall of the vacuum container 1. Further, outside the vacuum container 1, two annular permanent magnets 5 and 6 corresponding to the shapes of the cathode electrodes 2 and 3 and the anode electrode 4 are sandwiched in the vacuum container 1 with their opposite poles facing each other. It is arranged to be crowded. With this structure, a region surrounded by the cathode electrodes 2 and 3 and the anode electrode 4 is formed in the vicinity of the center of the vacuum container 1, and this region is the exhausted space 7.

The vacuum exhaust operation in the above configuration will be described below.

A vertical magnetic field H is generated by the permanent magnets 5 and 6 inside the vacuum container 1, and cold cathode discharge is generated by setting the cathode electrodes 2 and 3 to the ground potential and introducing a high voltage from the terminal 4b to the anode electrode 4. Occur. When the cold cathode discharge is generated in the magnetic field H in this manner, gas molecules are ionized and trapped in the cathode electrodes 2 and 3 (ion pump action).

Further, at the time of the above trap, the cathode material (titanium or the like) is sputtered from the cathode electrodes 2 and 3. Then, an active getter film (titanium getter or the like) is formed on the surface of the anode electrode 4 or the like, and gas molecules are adsorbed on the getter film (chemical adsorption action).

Evacuation is performed by such ion pump action and chemical adsorption action, but this embodiment is different from the conventional one,
As described above, the region surrounded by the elements (the cathode electrodes 2 and 3, the anode electrode 4) having the vacuum evacuation capacity becomes the exhausted space 7, and the vacuum exhaust is performed here.
Therefore, since the exhausted volume becomes the volume of the exhausted space 7, the exhausted volume can be made extremely small, and thus the condition (i) described above for achieving a high vacuum can be satisfied. Moreover, since it is exhausted from the entire surroundings, not through the exhaust port as in the past, in terms of gas flow, it is substantially the same as exhausted through a very large exhaust port, that is, the exhaust conductance. Therefore, the condition (ii) described above can be satisfied. Therefore, according to the present embodiment, both the above-mentioned conditions (i) and (ii) are satisfied, so that a high vacuum can be realized with a small device.

As described above, the compact and high-vacuum sputter ion pump of this embodiment is particularly suitable as a vacuum pump for an electron gun in an electron beam apparatus (electron microscope, electron beam exposure apparatus, electron beam LSI tester, etc.). An application example is shown in FIG. In the figure, an electron gun main body 10 having a cathode 11, an anode 12, a Wehnelt 13 and the like is fitted and fixed in the center of the vacuum container 1.
By forming the exhaust hole 14 in the side wall of the above, the above-described exhaust is performed in the path indicated by the arrow.

An electron gun that produces a high-intensity electron beam generally has a longer life and stability as the degree of vacuum increases. Therefore, in the past, a large ion pump had to be used,
Along with this, the entire electron beam apparatus has become larger. Therefore, as described above, the sputter ion pump of this embodiment, which is compact and can realize a high vacuum, is used.
By incorporating an electron gun as shown in the figure, it is possible to easily realize the miniaturization of the entire electron beam apparatus.

The material of the cathode electrodes 2 and 3 is preferably titanium, but is not limited to this as long as it is an active material capable of adsorbing gas molecules.

In addition to the electron gun described above, the present invention can be applied to various devices for which a high vacuum is desired.

〔The invention's effect〕

According to the sputter ion pump of the present invention, by making the entire pump annular and making the exhausted space near the center thereof, it is possible to achieve both a decrease in the exhausted volume and an increase in the exhaust conductance, and therefore a small size. It is possible to realize a high vacuum. Moreover, if the present invention is used as a vacuum exhaust pump for an electron gun in an electron beam apparatus, an effect that the entire electron beam apparatus can be downsized can be obtained.

[Brief description of drawings]

FIG. 1 is a partial sectional perspective view showing an embodiment of the present invention, FIG. 2 is a vertical sectional view showing the same embodiment, and FIG. 3 is an example in which the same embodiment is applied as a vacuum exhaust pump of an electron gun. FIG. 1 ... Vacuum container, 2, 3 ... Cathode electrode, 4 ... Anode electrode, 4a ... Cylinder, 5, 6 ... Permanent magnet, 7 ... Exhausted space.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Okubo 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor Yoshiro Goto 1015, Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa

Claims (2)

[Claims] 1. A vacuum container (1) comprising two cathode electrodes (2, 3) facing each other and a plurality of small cylinders (4a) arranged so as to be sandwiched by the two cathode electrodes. The anode electrode (4) having a combined structure, and two permanent magnets (5, 6) arranged so that opposite poles face each other and sandwich the vacuum container. In a sputter ion pump that evacuates by the action of sputtered atoms, the vacuum container (1) is formed into a cylindrical shape, and the cathode electrode (2, 3) and the anode electrode (4) are housed in the vacuum container. And the permanent magnets (5, 6) in an annular shape corresponding to the shapes of the cathode electrode and the anode electrode, and an exhausted space (7) near the center of the cylindrical vacuum container. Spattery characterized by Nponpu. 2. The sputter ion pump according to claim 1, wherein the cathode electrodes (2, 3) are made of titanium.