JPH03145580A - getta pump - Google Patents

Abstract

PURPOSE:To obtain a high exhaust speed by providing a laser device collecting and radiating laser rays to a getter material in a chamber from the outside of the chamber to gasify it in a pump forming a getter face on the inside of the chamber to absorb the gas molecules in the chamber when the getter material is gasified. CONSTITUTION:A titanium bulk 2 serving as a getter material is supported by a rotary guide unit 3 in a vacuum chamber 1, and a laser device 4 and a lens 5 for collecting laser rays are arranged on the outside of a translucent window 6 provided on the vacuum chamber 1. A cylindrical LN2 shroud 7 is arranged so as to surround the titanium bulk 2 in the vacuum chamber 1, and LN2 is circulated and fed from the outside of the chamber 1 into it. Laser rays from the laser device 4 are collected on the surface of the titanium bulk 2 via the lens 5 and the window 6, thus a fine region on the surface of the titanium bulk 2 is instantly heated in a short period, titanium is sublimated, and titanium grains are deposited on the inside face of the shroud 7 to form a getter face.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention creates a surface of a chemically active metal material, a so-called getter surface, in the chamber by vaporizing a getter material, thereby reducing gas molecules in the chamber. Incorporating the
The present invention relates to a so-called getter pump that is distantly related to ultra-high vacuum in a chamber, and relates to a pump that can be widely applied to devices that require ultra-high vacuum, such as molecular beam epitaxy equipment and surface analysis equipment.

<Prior Art> There are various types of getter pumps, but the one currently in common use is the titanium sublimation pump.

A titanium sublimation pump (hereinafter referred to as TSP) utilizes the Geck effect of a clean surface of titanium to vaporize titanium placed in a chamber to create a deposition surface within the chamber, and gas molecules within the chamber are vaporized. Or, when atoms are adsorbed on the clean titanium vapor deposited surface, they are trapped.By creating new titanium clean surfaces (deposited surfaces) one after another, gas molecules are continuously trapped.
It has an exhaust effect.

This TSP has characteristics such as a high pumping speed (proportional to the area of the titanium clean surface) and low cost.

Conventional TSP involves making a thin wire of titanium and sublimating the titanium by passing a large current through the thin wire in a chamber.

FIG. 2 shows an example of the configuration of a conventional TSP.

A titanium filament 22 is inserted into a vacuum chamber 21, which is a chamber to be evacuated, and a large current is applied (flashed) to the titanium filament 22 from a current introducing section 23 outside the chamber, thereby sublimating titanium. Here, shielding plate 2
4 is used to prevent titanium from going around inside the chamber 21. In this example, an LN and a shroud 25 are provided in the chamber 21 so as to surround the titanium filament 22, and titanium is mainly vapor-deposited on the inner surface 25a of the LN and the shroud 25, which is used as a getter surface.

<Problems to be Solved by the Invention> By the way, according to the conventional TSP as described above, when used together with a cryopump, there is a problem in that mutual installation positions are restricted. In other words, in conventional TSP, titanium is sublimated by flashing a current through a thin titanium wire, which has a thermal effect on the surrounding area, and it is difficult to bring TSP above the exhaust port of a cryopump, which is sensitive to heat. There are some difficulties.

In addition, in the conventional TSP, the shield +ri, 24 for preventing sublimated titanium from going around increases the flow resistance in the vicinity, and the pumping speed due to the titanium clean surface is controlled by the conductance at the shield plate 24. Therefore, the exhaust capacity is actually influenced by this shield plate 24.

The present invention has been made in view of these points, and an object of the present invention is to provide a getter pump that has extremely little thermal influence on other parts, has a large conductance, and has a high pumping speed.

<Means for Solving the Problems> A configuration for achieving the above object will be explained with reference to FIG. 1 corresponding to the embodiment.
A support body (for example, a rotary introduction machine) 3 that supports a getter material (for example, titanium bulk) 2 inside the chamber, and a laser device 4 that irradiates the getter material 2 with focused laser light from outside the chamber 1 to vaporize it. characterized by

<Function> When laser light is focused and applied to the getter material, only the focused area becomes high temperature, making it possible to sublimate the getter material in an extremely short time, with little thermal influence on other parts. Become.

In addition, when the getter material is sublimated by focused irradiation of laser light, the direction of vapor scattering is more directional than when flashing a current to the wire, making the cross-section plate smaller or eliminated. This makes it possible to increase the conductance and improve the pumping speed.

<Example> FIG. 1 is a block diagram of an embodiment of the present invention.

Inside the vacuum chamber 1 is a titanium bulk 2 which is a getter material.
is supported by the rotational introduction N3.

A light-transmitting window 6 is provided in the vacuum chamber 1, and a laser device 4 and a lens 5 for condensing laser light from the laser device 5 are provided outside the window 6. .

A cylindrical LN and shroud 7 are also arranged in the vacuum chamber 1 so as to surround the titanium bulk 2.
L N t can be cyclically supplied into the chamber from outside the chamber. The positional relationship between the LN2 shroud 7 and the titanium bulk 2 is such that the LN2 shroud 7 is located between the titanium bulk 2 and the window 6.
, the inner surface of most of the shroud 7 exists.

Laser light from the laser device 4 is focused on the surface of the titanium bulk 2 via a lens 5 and a window 6. As a result, a minute region on the surface of the titanium bulk 2 with a diameter of several μm to several hundred μm is instantaneously heated over a short period of time, for example, several RLs to several μs, and the titanium sublimes. The initial flight direction of the sublimated titanium is mainly the normal direction of the laser beam irradiation surface of the titanium bulk 2, and most of the titanium particles are LN and inside the shroud 7, especially without providing a shielding plate behind the titanium bulk 2. The getter surface 8 is formed here.

Here, as the laser device 4, it is possible to use infrared light for the purpose of heating and ultraviolet light to cause a photochemical reaction and sublimate, so laser devices with various wavelengths can be used. can. For example, for infrared light, a CO2 laser, YAG laser, etc. are suitable for the purpose of the present invention, and for ultraviolet light, an excimer laser can provide a large output and is suitable for the purpose of the present invention.

Furthermore, by pulsing the laser light, it becomes possible to create new getter surfaces every moment.

In the above embodiments, the LN2 shroud 7 is not necessarily required, and depending on the purpose of use, the inner wall surface of the chamber 1 itself may be used as the getter surface, or a dedicated getter chamber may be attached to the vacuum chamber and the getter chamber 7 may be used as the getter surface. It is also possible to use the inner wall surface as a getter surface.

<Effects of the Invention> As explained above, according to the present invention, the getter material is sublimated by irradiating the getter placed in the chamber with focused laser light from outside the chamber. The TSP is locally sublimated in an extremely short period of time, which reduces thermal effects compared to conventional TSP, and has the advantage that there are fewer restrictions on mutual placement, especially when used in conjunction with a cryopump. be.

In addition, since the getter material is sublimated by laser light irradiation, it is possible to control the scattering direction of the getter material to some extent, and the shielding plate can be eliminated or made extremely small, resulting in a lower conductance than conventional TSP. can be made larger, and the pumping speed is further improved.

Furthermore, unlike the conventional TSP, there is no need to introduce electricity into the chamber, so it is possible to reduce the occurrence of electrical troubles.

Furthermore, since the getter material can be in bulk form, the getter material can be easily increased in size, and the frequency of vacuum breakage for replacing the getter can be reduced without reducing the frequency.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of an embodiment of the present invention, Figure 2 is a conventional TSP
It is a figure showing an example of composition. 1... Vacuum chamber 2... Titanium bulk 3... Rotating introduction machine 4... Laser device 5... Lens 6... Window 7... LN2 shroud 8. ...Getta Mendo

Claims (1)

[Claims] In a pump that vaporizes a getter material placed in the chamber to create a getter surface inside the chamber and take in gas molecules in the chamber, a support body that supports the getter material in the chamber and a support for the getter material are used. A getter pump characterized by comprising a laser device that irradiates condensed laser light from outside the chamber to vaporize the chamber.