JPH0592953U - Sputter ion pump - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sputter ion pump that can be manufactured at low cost and can significantly improve the pumping speed. [Structure] A magnetic pole piece 6a for generating a magnetic flux between the cathodes 1a and 1b has an inexpensive ferrite magnetic pole piece 7a at the center thereof.
And a peripheral portion thereof is formed of a rare earth magnetic pole piece 8a which is expensive but has a high coercive force characteristic. Pole piece 6a
The magnetic pole pieces 6b arranged to face each other have the same structure. Therefore, it is possible to suppress a decrease in the magnetic flux density in the peripheral portion of the magnetic pole piece, and it is possible to increase the number of cylindrical anodes 2 that can be effectively operated. As a result, the pumping speed can be significantly improved while suppressing an increase in manufacturing cost to a minimum.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sputter ion pump that sputters a getter material to form an adsorption film and exhausts the gas.

[0002]

[Prior Art]

 FIG. 1 is a diagram for illustrating a conventional sputter ion pump. As shown in FIG. 1, a pair of magnetic pole pieces 4 a and 4 b are arranged, and the pair of magnetic pole pieces are connected to the yoke 5. Inside the pair of magnetic pole pieces 4a, 4b, a pair of cathodes 1a, 1b made of titanium (Ti) is arranged. These cathodes 1a and 1b are grounded. A large number of cylindrical anodes 2 made of stainless steel are arranged between the cathodes 1a and 1b such that their axial directions are perpendicular to the cathode surface. The anode 2 is held at a positive potential by the power supply 3, and the voltage required for discharging is applied between the anode and the cathode. The electrons involved in the discharge between the cathode and the anode make a swirling motion by the magnetic flux generated between the magnetic pole pieces 4a and 4b, and contribute to ionization with a higher probability. Ions generated by this discharge collide with the cathode and sputter the getter material to form a getter film having an exhaust action.

In the sputter ion pump configured as described above, when the magnetic flux density in the discharge space is B (Gauss: G) and the diameter of the cylindrical anode is d (cm), the following relationship is established. It has been known.

That is, in order to operate the sputter ion pump as a pump for high vacuum (10 ⁻⁶ to 10 ⁻⁸ Torr), B × d = approximately 1.2 (KG · cm) (1) Ultra high vacuum In order to operate as an ion pump for (10 ⁻⁹ to 10 ⁻¹¹ Torr), B × d ≧ 2.5 (KG · cm) (2) Therefore, a high vacuum ion pump or an ultra high vacuum ion pump is used. Respectively, the magnetic flux density B and the diameter d are selected so as to satisfy the above expressions (1) and (2), respectively.

[0005]

[Problems to be solved by the device]

 In the conventional sputter ion pump described above, the magnetic flux density of the magnetic field formed by the pole pieces 4a and 4b is not uniform in the discharge space. FIG. 2 shows the distribution of the magnetic flux density at the position AA 'in FIG. 1. As shown in this figure, the magnetic flux density sharply decreases at the ends of the magnetic pole pieces. Therefore, the area that can be effectively used as the exhaust space is much narrower than the width of the pole piece. For example, when the ferrite pole pieces whose opposing surfaces are about 100 mm × 150 mm are used and the pole spacing is 60 mm, the width and length that can be effectively used are about 80% each. Therefore, when the tubular positive electrode was used, only 3 (rows) × 5 (columns) = 15 (pieces) of anodes could be arranged. Therefore, in the conventional sputter ion pump, the exhaust speed was insufficient.

An object of the present invention is to provide a sputter ion pump that solves the above-mentioned conventional drawbacks and that can improve the exhaust speed and that is inexpensive to manufacture.

[0007]

[Means for Solving the Problems]

 Therefore, the present invention comprises a pair of magnetic pole pieces arranged to face each other, a pair of cathodes arranged to face the inside of the magnetic pole pieces, and a plurality of cylindrical anodes arranged between the cathodes. In the ion pump, the magnetic pole piece is characterized by a sputter ion pump in which the peripheral portion is formed of a member having a higher coercive force than the central member.

[0008]

[Action]

 Since the peripheral portion of the magnetic pole piece is formed of a member having a higher coercive force than the central portion, it is possible to suppress a decrease in the magnetic flux density in the peripheral portion of the magnetic pole piece without significantly increasing the manufacturing cost. Therefore, it becomes possible to dispose the tubular anode also in the pump peripheral portion where the disposition of the tubular positive electrode has been refrained from due to the decrease in the magnetic flux density, and the pumping speed can be improved.

[0009]

【Example】

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

FIG. 3 is a view for showing an embodiment of the present invention, in which the same components as those in FIG. 1 are designated by the same reference numerals. In FIG. 3, 6a and 6b are magnetic pole pieces, and the magnetic pole piece 6a is formed by a composite of a magnetic pole piece 7a made of ferrite in the central portion and a rare earth magnetic pole piece 8a having a high coercive force. Similarly, the magnetic pole piece 6b is also formed by a composite of the ferrite magnetic pole piece 7b and the rare earth magnetic pole piece 8b.

In the sputter ion pump configured as described above, the distribution of the magnetic flux density on the plane AA ′ in FIG. 3 becomes uniform over a wide range, as shown in FIG. The decrease in magnetic flux density is slight. Therefore, as shown in FIG. 3, conventionally, only 5 (rows) of anodes 2 that can be effectively operated can be arranged, whereas 6 (rows) of anodes 2 can be arranged as shown in the figure, and the number of columns is also 1 Since the number of columns can be increased, a total of 24 (a number) of tubular anodes can be arranged. As a result, it became possible to improve the exhaust speed by 60%. Rare earth magnets have high performance but are expensive. However, in the present invention, since the rare earth magnet is used only in the peripheral portion, the increase in manufacturing cost can be minimized.

The above-described embodiment is only one embodiment of the present invention, and can be modified and implemented. For example, in the above-described embodiment, the high-performance pole piece portion of the composite pole piece is formed of a rare earth magnet, but it may be formed of another magnet having a high coercive force characteristic such as an arconi magnet or a plastic magnet. You can

[0013]

[Effect of the device]

 In the present invention, the central portion of the pole piece is formed of a magnetic material having a low coercive force characteristic but is inexpensive, and the peripheral portion is formed of a magnetic material having an expensive but high coercive force characteristic. According to the present invention, it is possible to suppress a decrease in magnetic flux density in the periphery of the pole piece, and thereby increase the number of anodes that can be effectively operated. Therefore, according to the present invention, it is possible to provide a sputter ion pump in which the increase in the manufacturing cost is suppressed to the minimum and the exhaust speed is significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a conventional sputter ion pump.

FIG. 2 is a diagram for explaining a decrease in magnetic flux density in a peripheral portion of a conventional sputter ion pump.

FIG. 3 is a view showing an embodiment of the present invention.

FIG. 4 is a diagram showing a distribution of magnetic flux density on the plane AA ′ of FIG. 3.

[Explanation of symbols]

 1a, 1b cathode 2 cylindrical anode 3 power supply 4 4a, 4b, 6a, 6b pole piece 5 yoke 7a, 7b ferrite pole piece 8a, 8b rare earth pole piece

Claims (1)

[Scope of utility model registration request] 1. A sputter ion comprising a pair of magnetic pole pieces arranged to face each other, a pair of cathodes arranged to face each other inside the magnetic pole piece, and a plurality of cylindrical anodes arranged between the cathodes. In the pump, the sputter ion pump is characterized in that the magnetic pole piece has a peripheral portion formed of a member having a higher coercive force than the central member.