JPH025172Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a flexible pipe suitable for conducting high-purity gas.

(Conventional structure and its problems) Conventionally, for example, diffusion furnaces used in semiconductor manufacturing processes have been used to produce ultrahigh purity materials of 99.99999% or higher.
Particles (dust) with a size of 0.1μm or more
2.8, extremely clean gas of less than 5 is required.

If the piping leading to the diffusion furnace is a fixed piping, the above requirements can be met by using a metal tube such as stainless steel with a polished inner surface.
Metal pipes cannot be used for pipes that flow HCl gas because of the risk of corrosion. In addition, as the piping that connects to the end of the furnace core tube of a diffusion furnace needs to be attached and detached, a flexible tube must be installed. The pipe is made of a material that has some flexibility and high chemical resistance.

However, compared to metal tubes, this type of synthetic resin tube has an extremely high air permeability that allows molecules with a size of 3 Å to 5 Å to pass through. Contamination with ingredients and moisture cannot be avoided.

For example, if the outside diameter is
Experiments have confirmed that when Ar gas with a purity of 99.99999% is passed through a Teflon PFA pipe with a length of 12.7mm and a wall thickness of 1.0mm, the purity drops to 99.9999% while passing through a length of approximately 2m. .

In a diffusion furnace, a dopant gas such as arsine, phosphine, or deiborane is usually mixed with nitrogen gas, but if oxygen from the air is mixed into this gas, unexpected oxides may form on the silicon surface of the product. As a result, it is impossible to obtain a product having a uniform diffusion layer, which adversely affects the yield of high-quality products.

Also, using a metal bellows pipe as a flexible pipe can solve the problem of air permeability, but the bellows pipe has many curved folds due to its structure, so once particles are mixed in, it is impossible to completely remove them. It is possible.

(Purpose of the invention) This invention eliminates the above-mentioned problems. It reliably prevents the intrusion of oxygen and moisture from the outside, enables the conduction of high-purity gas, and has flexibility, chemical resistance, and resistance. This provides a flexible pipe with excellent corrosion resistance.

(Structure of the invention) In order to achieve the above object, the flexible pipe of the invention, as shown in FIG. The pipes 1 and 2 are fitted together to form a double pipe, and both ends of the pipes 1 and 2 are sealed to each other, and the gap 3 between the pipes 1 and 2 is filled with an inert gas.

The sealing may be done by one or two ring-shaped packings 4, 5 as shown in FIG. 2, or by adhesive at both ends of the metal bellows pipe 2 as shown in FIG. The inner peripheral surface of the inner pipe 1 may be brought into close contact with the outer peripheral surface of both ends of the inner pipe 1.

Further, the metal bellows pipe 2 disposed as the outer pipe may have the concave arc-shaped inner circumferential surface of its curved folds in contact with or close to the outer circumferential surface of the synthetic resin inner pipe 1.

(Explanation of Embodiments) The embodiments of the present invention will be explained with reference to the drawings.
is a synthetic resin inner pipe made of flexible and chemical-resistant pipes such as Teflon PFA resin pipes and Tefzel pipes, and its outer circumferential surface is covered with a metal bellows pipe 2 over almost its entire length to provide flexibility. It is formed into a double pipe.

Reference numeral 6 denotes a connecting short tube made of Teflon resin or SUS that is fitted onto the outer circumferential surface of both ends of the inner pipe 1, and a circumferential groove 7 in which O-rings 4 and 5 are fitted is formed on the outer circumference of the inner end. , these O-rings 4 and 5 are brought into close contact with the inner circumferential surface of both ends of the metal bellows pipe 2 to seal both ends of the gap 3 formed between the inner circumferential surface of the bellows pipe 2 and the outer circumferential surface of the inner pipe 1, thus sealing. The gap 3 between the two pipes 1 and 2 is filled with an inert gas such as argon. Also, this short pipe 6
A female screw portion 8 that opens toward the end of the inner pipe 1 is integrally provided at the outer end of the inner pipe 1.
A male threaded portion 10 formed on the outer periphery of the inner end of a short tubular connector 9 made of Teflon resin is screwed into the connector.

Reference numeral 11 denotes an O-ring that seals between the expanded inner circumferential surface of the inner end of the connector 9 and the outer circumferential surface of the inner pipe 1;
In the figure, the end face of the protrusion part 12 protruding inwardly from the female screw part 8 of the short pipe 6 is sandwiched between the inner end expanding inclined surfaces 13 of the connector 9, and in FIG. It is sandwiched between the end surface of the shaft body 14 fitted into the inner pipe 1 inside the female threaded portion 8 of the short tube 6 and the inner end expanding inclined surface 13 of the connector 9.

For example, the flexible pipe configured in this manner has one end connected to a quartz tube (not shown) of a diffusion furnace via a connector 9, and the other end connected to a fixed pipe (not shown) via the connector 9. A device used to supply a mixed gas of nitrogen gas and a dopant gas such as arsine or phosphine into the diffusion furnace from the fixed pipe through the inner pipe 1 to form a diffusion layer on the surface of the silicon piece. It is.

(Effects of the invention) As described above, according to the flexible pipe of the invention, the metal bellows pipe 2 is fitted onto the synthetic resin inner pipe 1 having flexibility and chemical resistance to form a double pipe. Because of its flexibility and bendability, it is easy to connect to fixed piping, etc., and since the gap 3 between both pipes 1 and 2 is filled with inert gas, it is suitable for use in semiconductor manufacturing equipment. When used as piping, there is no risk of air components, moisture, etc. entering from the outside into the gas flowing through the inner pipe 1, and the gas can be supplied to a diffusion furnace etc. while maintaining high purity. Therefore, highly accurate products can be manufactured.

In addition, since the inner pipe 1 is made of synthetic resin, there is no risk of corrosion unlike metal pipes, and since the inner surface is smooth, it is easy to remove dust etc. Metal bellow pipe 2 installed as an outer pipe even if gas leaks from the inner pipe
It can reliably prevent leakage to the outside and can be used safely.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention. Figures 1 to 3 are simplified sectional views of some of the three examples, and Figures 4 and 5 show the main parts with the connector attached. FIG. 1...Synthetic resin inner pipe, 2...Metal bellows pipe, 3...Gap, 4, 5...Seal portion.

Claims (1)

[Scope of utility model registration request] A metal bellows pipe 2 is fitted onto a synthetic resin inner pipe 1 having flexibility and chemical resistance with an appropriate gap 3 to form a double pipe, and both pipes 1 and 2 are fitted.
Seals 4, 5 between both ends of the pipes 1,
A flexible pipe in which an inert gas is filled in the gap 3 between the two.