WO1992014540A1

WO1992014540A1 - Method for homogenization treatment of mixed gases

Info

Publication number: WO1992014540A1
Application number: PCT/JP1992/000202
Authority: WO
Inventors: Kazuya Inoue; Hiroshi Ogawa; Susumu Kikuchi; Takahiko Sudo
Original assignee: Osaka Sanso Kogyo Ltd.
Priority date: 1991-02-25
Filing date: 1992-02-25
Publication date: 1992-09-03
Also published as: CA2079898A1; JPH04358530A

Abstract

According to the present invention, two or more kinds of gases can be homogeneously mixed without generating dust. A method of homogeneously mixing at least two kinds of gases contained in a container, comprising the steps of: (a) inclining the container from an upright position to a substantially 90° tilted position; (b) returning the container to the upright position from the substantially 90° tilted position; and (c) repeating steps (a) and (b) at least one more time is disclosed.

Description

METHOD FOR HOMOGENIZATION TREATMENT OF MIXED GASES

Field of Application The present invention relates to a method for mixing a mixed gas contained in a container. Prior Art

With recent progress in the semiconductor industry, various gases are now used which are required to be highly pure and particle-free. Accordingly, the interior of the factories which produce these gases must be kept extremely clean. In the semiconductor industry, mixtures of gases are sometimes used. In such cases, at least two kinds of substantially pure gases must be mixed in a gas producing factory.

Fig. 1 shows a conventional apparatus for ho ogene- ously mixing at least two kinds of gases.

In the apparatus, two or more kinds of gases to be mixed with each other are charged in a gas container 1. Container 1 is then put on a rolling machine 2 as shown in Fig. 1. Rolling machine 2 in Fig. 1 comprises two horizontal axles 3, a set of three rollers 4 connected to axles 3 and a rotator 5 attached to the end of at least one of the axles 3. After putting the charged container on the rolling machine 2, the gases are homogeneously mixed within the container 1 by rotating the axles 3 by means of the rotator 5 thereby rotating the container 1. However, particles are generated in this method (i) from the portion in which the container contacts with the roller and (ii) from the interior of the rotator. Moreover, the coated surface of the container is damaged creating dust particles from the coating. The particles thus generated make it difficult to maintain a clean room.

Since the surface of the container is spoiled or contaminated by the prior method, it is necessary to recoat the container surface or cover the entire container with a piece of cloth after the homogenization treatment. In order to carry out the homogenization treatment according to the prior method, countermeasures are taken for preventing the generation of dust. For instance, air is locally exhausted where dust is generated.

Summary of the Invention The present inventors have developed a method by which dust does not generate during a homogenization treatment of gases to be mixed. The present invention relates to a method of homogene¬ ously mixing at least two kinds of gases contained in a container, comprising the steps of:

(a) inclining the container from an upright position to a substantially 90° tilted position; (b) returning the container to the upright position from the substantially 90° tilted position; and

(c) repeating steps (a) and (b) at least one more time, preferably 3 - 10 times.

In the invention, the container charged with the gases to be mixed may be manually inclined from the upright position to substantially 90" tilted position, and returned to the upright position. This may be accomplished by attaching the container to a wall and rotating the wall through an angle of 90 degrees. Immediately after charging, the gas charged first is located in the lower part of the container and the gas charged last is located in the upper part of the container. In the prior method, the mixing of the gases in the container is carried out by a fraction between the inner wall of the container.

In the present invention, the gas in the lower part of the container moves toward the upper part of the container and the gas in the upper part of the container moves toward the lower part of the container when the container is inclined at an angle of 90 degrees from the vertical. When the container is inclined from the upright position to a substantially 90 degree tilted position, kinetic energy acts on the gases in the container in the direction of inclination of the container. As a result, the gases move according to the law of inertia.

In the prior method, dust is generated by the friction between the roller and the container surface. However, since no roller is used according to the present invention, no dust is generated due to fraction between the rollers of the container's surface. Moreover, the dust generated from the rotator in the prior method is not present in the present invention because no rotator is used in the present invention. Since there is no dust or particulate contamination in the present invention, there is no need to countermeasure such contamination.

Embodiment Comparison of concentration in mixed gases between the present invention and the conventional method. Mixed Gas Species Present Invention Prior Method C0₂ + He Mixture C0₂ 10.47% C0₂ 10.40% S1H4 + ₂ Mixture SiH₄ 4.16% SiH₄ 4.15% PH₃ + H₂ Mixture PH₃ 14.7 ppm PH₃ 14.6 ppm

The gases are charged into several containers by a manifold. In order to carry out the homogenization treatment according to the prior method, the container must be removed from the manifold to rotate the container. However, since the containers do not rotate in the present invention, several containers can be simultaneously subjected to homogenization treatment without removing the containers from the manifold.

Moreover, when a container is connected to a gas charging apparatus by means of a flexible tube, the container can be subjected to homogenization treatment without removing the connection, so that a series of operations up to analysis can be carried out without any attachment or removal of the connecting part.

The present invention can also be applied to the production of gases for medical use and gases for food use.

Claims

1. A method of homogeneously mixing at least two kinds of gases contained in a container, comprising the steps of:

(a) inclining the container from an upright position to a substantially 90° tilted position;

(b) returning the container to the upright position from the substantially 90° tilted position; and

(c) repeating steps (a) and (b) at least one more time.

2. The method of Claim 1 wherein said steps (a) and (b) are repeated 3 - 10 times.