JPS61291965A - Superhigh-vacuum chamber - Google Patents

Abstract

PURPOSE:To reduce heat loss and to lower the necessary mechanical strength of an internal chamber by putting the internal chamber provided with heaters on the outside in an external chamber to form a double structure. CONSTITUTION:This superhigh-vacuum chamber has a double structure consisting of an external chamber 5 and an internal chamber 8 put in the chamber 5. Exhaust systems such as a rotary oil pump 11 and a diffusion oil pump 13 are connected to the external and internal chambers 5, 8, respectively. The internal chamber 8 is provided with heaters 15 on the outside.

Description

[Detailed Description of the Invention] [Summary] In the semiconductor manufacturing process, there are many steps in which a wafer is placed inside a vacuum apparatus and processed, and the degree of vacuum in the vacuum chamber is 10-' Torr or less. It is difficult to maintain the degree. In the present invention, by duplicating the vacuum chamber, a chamber capable of obtaining a vacuum degree of 10-' Torr or less has been realized.

[Industrial application field]

The present invention relates to an ultra-high vacuum chamber that facilitates the maintenance of ultra-high vacuum and the pretreatment process for removing adsorbed gas.

In the manufacture of semiconductor devices, a vacuum chamber is used in many processes such as a vacuum evaporation process for forming Al wiring, which is called a metal process, an exposure process using an electron beam, and a sputtering process.

In conventional devices, the degree of vacuum in these vacuum chambers is often about 10-' Torr.

However, in order to ensure yield and reliability as the degree of integration of semiconductor devices increases, it is necessary to further improve the degree of vacuum in the vacuum chamber used in the above process to avoid the influence of impurities. It turns out that there is. For this reason, improvements to vacuum chambers are also desired.

[Conventional technology]

The general structure of a conventional vacuum chamber is shown in FIG. Width and depth are 60-70cm, height 50-60cm respectively
The vacuum chamber 1 with dimensions of about cm is made of iron, stainless steel,
Manufactured from thick material such as aluminum.

The top cover 2 is removable and is fastened to the main body 3 by a metal backing 4 during use. An exhaust system such as an oil rotary pump, oil diffusion pump, cryopump, etc. is connected to the lower part of the main body 3.

In FIG. 2, jigs, parts, etc. installed in the chamber necessary for the semiconductor processing process are omitted.

Since the vacuum chamber is exposed to atmospheric pressure over its entire surface during use, it is made of a thick metal material, and the adsorbed gas is released within the chamber during use. Therefore, it is necessary to pre-evacuate the chamber before use.

For preliminary exhaust, a heater 15 is installed on the outer or inner wall of the chamber.
This is done by heating the chamber by wrapping it around the chamber, or by irradiating the outer or inner walls of the chamber with an infrared lamp, but even if the chamber is heated to, for example, 200 degrees Celsius for several tens of hours, this is a fairly troublesome process. It becomes.

[Problem that the invention seeks to solve]

When using the vacuum chamber having the conventional structure described above, there is a problem in that preliminary evacuation of the chamber in order to increase the degree of vacuum is a large-scale work.

That is, in this preliminary evacuation, since the heat capacity of the chamber is large, a large amount of electric power is required to heat the chamber, which also has a great influence on the surroundings.

Therefore, if a vacuum chamber is used without sufficient preliminary evacuation, the adsorbed gas will not be removed sufficiently and the problem of impurities adhering to the semiconductor during the process will be unavoidable.

[Means for solving problems]

The above-mentioned problem is that the structure of the vacuum chamber is a double tank consisting of an external chamber and an internal chamber housed in the external chamber, and an exhaust device is connected to each of the external chamber and the internal chamber, and the external surface of the internal chamber is This problem is solved by the structure of the ultra-high vacuum chamber of the present invention, which is equipped with a heating device having a heater wrapped around it.

[Effect]

By adopting the double chamber vacuum chamber structure, the outside of the internal chamber is also evacuated during preliminary evacuation, so that heat loss due to convection can be almost prevented during heating by the heater. Furthermore, since thermal radiation is also reflected from the external chamber, the heating power of the heater is significantly reduced.

Another effect is that the internal chamber does not require mechanical strength to withstand atmospheric pressure, so it is possible to use a metal material with a sufficiently thin wall thickness.

〔Example〕

An embodiment according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a structural sectional view of the ultra-high vacuum chamber of the present invention. The vacuum chamber has a double tank structure, and the outer chamber 5 is composed of a main body 6 and an upper lid 7, and the inner chamber 8 is also composed of a main body 9 and an upper lid 10.

A vacuum pump system is connected to each chamber,
Since the pump for the external chamber does not require a high degree of vacuum, it is sufficient to use only the oil rotary pump 11, which has an ultimate vacuum of about 10-'' Torr and a high pumping speed.

The exhaust system connected to the internal chamber needs to achieve an ultimate vacuum of 10-' or more, so in addition to the usual oil rotary pump 12 and oil diffusion pump 13, an ion pump, sublimation pump, cryopump, etc. are used. A dry pump 14 is connected to obtain a high degree of vacuum.

A heating heater 15 is attached to the outer surface of the internal chamber, and this heats the internal chamber during preliminary evacuation.

In this ultra-high vacuum chamber, the space between the inner chamber and the outer chamber is maintained at a low vacuum, so there is almost no heat loss due to convection when heated by the heater, and there is also no radiant heat in the outer chamber. Since it is reflected from the inner surface, the heating power of the heater is significantly reduced.

Furthermore, since the internal chamber is maintained in a vacuum both inside and outside during use, mechanical strength against atmospheric pressure is not required. Therefore, it is possible to use a material with a thin wall thickness of about 1 mm.

For this reason, the heat capacity of the internal chamber is reduced, which contributes to shortening the heating time and reducing the amount of gas occluded in the internal chamber.

〔Effect of the invention〕

As explained above, by using the ultra-high vacuum chamber of the present invention, preliminary evacuation of the vacuum chamber is facilitated, and the heating power required for this purpose is small. The high vacuum process using this equipment can significantly reduce the adhesion of impurities.

[Brief explanation of drawings]

FIG. 1 is a structural sectional view of an ultra-high vacuum chamber according to the present invention, and FIG. 2 is a structural sectional view of a conventional vacuum chamber. In the drawings, 1 is a vacuum chamber, 2.7.10 is an upper lid, 3.6.9 is a main body, 4 is a metal backing, 5 is an external chamber, 8 is an internal chamber, 11.12 is an oil rotary pump, and 13 is an oil 14 is a dry pump, and 15 is a heater. 3-4 Toro month 11・υ phase Ruhiko j Ka nko size Ki sacrilege--Ogawa Omori Yσ mouth diagram Figure 1 Figure 2

Claims (1)

[Claims] Consisting of a double tank consisting of an external chamber (5) and an internal chamber (8) accommodated in the external chamber, an exhaust device is connected to each of the external chamber and the internal chamber, and An ultra-high vacuum chamber characterized by having a heating device (15) on its outer surface.