JP6330872B2 - Storage container - Google Patents

Description

  The present invention relates to a storage container suitable for storing corrosive substances such as ozone gas and having at least an inner surface made of titanium.

  Ozone gas is used as an oxidizing agent when forming an oxide film by ADL (Atomic layer Deposition) or the like in a semiconductor device manufacturing process. Therefore, an ozone gas storage container that stores ozone gas manufactured by an ozone generator is used in a semiconductor device manufacturing line.

  Conventionally, a stainless steel container is used as an ozone gas storage container. The stainless steel ozone gas storage container has a mirror finish on the inner surface of the container by electrolytic polishing, and a passive film is formed thereon. The passive film is formed by allowing ozone gas having an oxygen resistance ratio of 50% or more to act on a mirror-finished stainless steel for about 48 hours (Patent Document 1) or allowing ozone gas having a concentration of 20 vol% or more to act for about 20 hours. (Patent Document 2).

JP-A-8-85548 JP 2000-191305 A

  However, in the manufacturing process of a stainless steel ozone gas storage container, a passive state in which ozone gas with an oxygen ratio of 50% or more is applied to a mirror-finished stainless steel surface for about 48 hours or ozone gas with 20 vol% or more for about 20 hours. Since a film forming step is required, there is a problem that the time required for manufacturing the ozone gas storage container cannot be shortened and the cost is high.

  Further, as shown in FIG. 6, a top plate 3 is welded to one end of a cylindrical body 2, and a bottom plate 5 is welded to the other end, and a stainless steel pipe 7 is used as an inlet / outlet of ozone gas to the top plate 3. In the manufacturing process of the conventional stainless steel ozone gas storage container 1X to which 8 is welded, first, the surfaces of the body portion 2, the top plate 3 and the bottom plate 5 are mirror-finished by electrolytic polishing, and the top plate 3 is made of a stainless steel pipe. 7 and 8 are inserted, and the pipes 7 and 8 are fillet welded from both the front and back surfaces of the top plate 3, then the top plate 3 and the body 2 are fitted and welded by Tig welding, and the body 2 and the bottom plate 5 are also welded. Are fitted and welded in the same way. And ozone gas is made to act in a container and a passive film is formed in the container inner surface.

  However, in the welded part 10x by the fitting welding, the bead 11 is formed outside the ozone gas storage container 1X, but the gap 12 is formed inside, so that particles generated during welding or particles present in the surrounding environment are formed. Accumulates in the gap 12. This particle exists even after electrolytic polishing or formation of a passive film, and there is a problem that decomposition of ozone gas filled in the ozone gas storage container 1X is promoted by the particle.

  On the other hand, in order to prevent the gap 12 from being formed inside the container of the welded portion 10x, it is conceivable to perform butt-back welding as shown in FIG.

  However, when a stainless steel material is butt-welded and back-surface welded, there is a problem that a passive film is not formed on the back-surface portion 13. Therefore, a container formed by butt back wave welding cannot be used as an ozone gas storage container.

  Furthermore, the conventional stainless steel ozone gas storage container 1X is heavy and difficult to handle during transportation and installation.

  In response to these problems, the present invention is a storage container suitable for storing corrosive substances such as ozone gas, and particles formed during welding do not accumulate in the container, and the process of forming a passive film, which takes time and cost, is performed. It is an object of the present invention to provide a new storage container that can be omitted and can be reduced in weight.

  The inventor makes the surface material on at least the inner side of the storage container made of titanium. Even if the welding of the body and the top plate or the welding of the body and the bottom plate is butt-welded, the back surface is dense. A passive film is formed, and this passive film can be instantly formed by air oxidation at room temperature. Also, in the semiconductor device production line, only a few vol% ozone gas used in the production line is allowed to act. Since the passive film can be formed instantaneously, it has been found that it is not necessary to separately provide a passivating film forming step, and the present invention has been conceived.

  That is, the present invention is a storage container having a top plate at one end of a cylindrical body and a bottom plate at the other end, at least the inner surface of the storage container is formed of titanium, and the top plate and the bottom plate are respectively Provided is a storage container in which a body portion is butt-back welded.

Further, the present invention is a method for manufacturing a storage container having a top plate at one end of a cylindrical body and a bottom plate at the other end as a method for manufacturing the above storage container,
Polishing the inner surface of the storage container of at least the cylindrical body, the top plate having the rising portion on the outer peripheral portion, and the bottom plate having the rising portion on the outer peripheral portion. Polishing process,
Inserting a pipe made of titanium at least on the inner surface of the top plate and welding the pipe and the top plate;
Provided is a method of manufacturing a storage container, which includes a step of butt-welding and back welding a body part and a bottom plate, and a body part and a top plate.

  Since the inner surface of the storage container of the present invention is made of titanium, the surface can be formed without providing a passive film forming step of allowing high concentration ozone gas to act for a long time as in the case of forming a passive film on stainless steel. A passive film is formed. Therefore, productivity of a storage container can be improved and manufacturing cost can be reduced.

  In addition, the passive film is not formed on the back wave part when stainless steel is butt-back welded, whereas it is surprisingly easy to form on the back wave part when titanium material is butt-back welded. Is done. Therefore, when the storage container is formed from a cylindrical body, top plate, and bottom plate, the inner surface of which is made of titanium, and the inner surface is covered with a passive film, the top plate, the body, and the bottom plate are butted together. Back wave welding is possible, and it is not necessary to fit and weld. For this reason, according to the storage container of this invention, the problem of the residual of the particle which adheres in the container from the surroundings and the particle | grains produced when fitting welding is performed is eliminated. Therefore, when ozone gas that easily decomposes due to the presence of particles in the storage container is stored in the storage container of the present invention, it is possible to suppress a decrease in ozone gas concentration due to decomposition during storage. It is suitable as a storage container.

  Further, since the passive film of titanium is dense and strong, the storage container of the present invention is a storage container for corrosive substances such as various corrosive gases such as hydrogen sulfide, sulfurous acid gas and wet chlorine gas, and corrosive liquids. Can also be used.

  Further, since the storage container of the present invention is made of titanium at least on the inner surface, the weight can be reduced with respect to the stainless steel container. In particular, when the entire storage container is made of pure titanium, the weight is reduced. Is reduced to about 60%. Therefore, transportation and installation become easy.

Drawing 1A is a perspective view of storage container 1 of an example. Drawing 1B is an AA sectional view of storage container 1 of an example. FIG. 2 is a cross-sectional view of a deformation mode of the welded portion between the top plate and the trunk portion. FIG. 3 is a cross-sectional view of a storage container according to another embodiment. FIG. 4 is a system diagram for performing an ozone gas concentration attenuation test. FIG. 5 is a relationship diagram between the retention time of the ozone-containing gas in the storage container and the ozone concentration. FIG. 6 is a cross-sectional view of a conventional stainless steel ozone gas storage container in which a body portion and a top plate and a body portion and a bottom plate are fitted and welded. FIG. 7 is an enlarged cross-sectional view of the stainless steel body and the top plate welded by butt-back welding.

  Hereinafter, the present invention will be specifically described with reference to the drawings. In each figure, the same numerals indicate the same or equivalent components.

  FIG. 1A is a perspective view of a titanium storage container 1 according to an embodiment of the present invention, and FIG. The storage container 1 has a top plate 3 at one end of a cylindrical body 2 and a bottom plate 5 at the other end. These are all made of titanium. More specifically, it is formed from a pure titanium material, and for example, a second type titanium material is preferable.

  In addition, the storage container of this invention should just be the inner surface being formed with titanium at least, and the whole storage container does not need to be formed with titanium. Therefore, for example, the body portion, the top plate, and the bottom plate may be formed of a clad material having two or more layers of metal such as stainless steel or aluminum and titanium. When the entire storage container is formed of titanium, the storage container can be reduced in weight compared to the case where a clad material is used. On the other hand, using titanium and stainless clad material increases the strength and reduces the material cost compared to the case where the entire storage container is made of titanium, while using titanium and aluminum clad material makes it lighter. Can be realized.

  The body part 2 can be formed into a cylindrical shape with a plate thickness t2 of 0.1 to 20 mm, the top plate 3 and the bottom plate 5 are each substantially disk-shaped, and the plate thickness at the center is set to 0.1 to 30 mm. be able to. The top plate 3 and the bottom plate 5 have rising portions 4 and 6 on the outer peripheral portions, respectively. The wall thickness t4 of the rising part 4 of the top plate 3 and the wall thickness t6 of the rising part 6 of the bottom plate 5 are equal to the wall thickness t2 of the body part 2, respectively. Back-wave welding is performed, the rising portion 6 of the bottom plate 5 and the body portion 2 are also butt-back welded, and a back-wave portion 13 is formed inside the storage container of these welds 10. Accordingly, there is no gap 12 (FIG. 6) formed when the body 2 and the top plate 3 or the body 2 and the bottom plate 5 are fitted and welded inside the storage container 1, and particles generated during welding are present. The structure is difficult to accumulate.

  Further, in order to prevent particles from collecting on the inner surface of the storage container 1 at the corner 3a (the base of the rising part 4) of the top plate 3 and the corner 5a (the base of the rising part 6) of the bottom plate 5. Each is preferably rounded.

  In addition, as shown in FIG. 2, the rising plate 4 is not formed on the top plate 3, and the plate-like top plate 3 and the body 2 can be butt-welded and back wave welded. It is difficult to round the corners that are formed. Therefore, it is preferable to provide the rising part 4 in the top plate 3, and butt-weld the rising part 4 and the trunk | drum 2 and back-welded. The welding of the bottom plate 5 and the body 2 is the same.

  On the other hand, a titanium pipe 7 is welded to the top plate 3 as an inlet for stored items, and a titanium pipe 8 is welded as an outlet for stored items. In the present invention, these pipes may be formed of titanium at least on the inner surface.

  The pipes 7 and 8 are welded from the front end side thereof, and a bead 11 is formed inside the storage container of these welded portions 10b. Note that a gap 14 exists outside the storage container of the welded portion 10b. However, since this gap 14 is outside the storage container 1, it does not cause particles to be mixed into the stored items in the storage container 1.

  Further, in the present invention, when the top plate 3 and the pipes 7 and 8 are welded, as shown in FIG. 3, both the front and back sides of the top plate 3 are formed so that the beads 11 are formed both inside and outside the storage container. The top plate 3 and the pipes 7 and 8 may be welded to the fillet, but it is sufficient that a bead is formed on one side of the top plate 3 in terms of welding strength, and particles are formed on the inner surface of the storage container 1. It is preferable to weld so that the beads 11 are formed inside the storage container as shown in FIG.

  On the other hand, a welding rod made of pure titanium is used for welding the body 2 and the top plate 3, the body 2 and the bottom plate 5, and the top plate 3 and the pipes 7 and 8, as will be described later. Therefore, in the storage container 1 of the present embodiment, the trunk portion 2, the top plate 3, the bottom plate 5, the inlet pipe 7, the outlet pipe 8, and all of these welds 10, 10b are formed of titanium. ing.

  Furthermore, the surface roughness (Ra) of the inner surface of the storage container 1 is preferably as smooth as 0.14 μm or less. The surface roughness (Ra) can be measured with a commercially available surface roughness measuring instrument (for example, Surf Test SJ-201 series, Mitutoyo Corporation).

  As described above, according to the storage container of the present invention, since the entire inner surface is formed of titanium smoothly, by placing the storage container in air at room temperature, or in the production line of semiconductor devices, an ozone generator By applying the produced ozone gas of several vol%, a dense passive film is instantaneously formed on the entire inner surface. Further, even if the inner passive film is damaged by an external impact or the like, the damaged passive film is instantly regenerated by introducing ozone gas into the container. Therefore, when this storage container 1 is used as an ozone gas storage container, the concentration of the filled ozone gas is greatly reduced during storage due to damage to the passive film inside the container, compared to a conventional stainless steel ozone gas storage container. Does not occur, and the rate of reduction in ozone gas concentration during storage can be suppressed. Therefore, the storage container of the present invention can be suitably used in a semiconductor device production line or the like.

The storage container 1 of an Example can be manufactured as follows.
First, machining is performed to form a cylindrical body 2, a top plate 3 having a rising portion 4 on the outer peripheral portion, and a bottom plate 5 having a rising portion 6 on the outer peripheral portion from a pure titanium material, preferably a second type titanium material. Do. In this case, the top plate 3 and the bottom plate 5 are preferably formed by rounding the rising portions 4 and 6 and the corner portions 3a and 5a by cutting. In addition, although the trunk | drum 2, the top plate 3, and the baseplate 5 can also be shape | molded by a drawing process, casting, etc., a cutting process is preferable from the point which suppresses cost. Moreover, you may use the end plate formed with the pure titanium material.

  Next, the grinding | polishing process of the trunk | drum 2, the top plate 3, and the bottom plate 5 is performed. In this polishing step, it is preferable to finish at least the inner surface of the storage container to a mirror surface with a roughness (Ra) of 0.14 μm or less. Therefore, as a polishing method, for example, it is preferable to first buff the surface which is at least the inside of the storage container, and then perform chemical polishing or electrolytic polishing. In buff polishing, # 400 buff is used, and in chemical polishing, a mixed solution of sulfuric acid, nitric acid and hydrofluoric acid (for example, Escreen S-22, Sasaki Chemical Co., Ltd.) is used. The immersion treatment is preferably performed for several seconds to several tens of seconds depending on the temperature and the like.

  Next, the titanium pipes 7 and 8 of the top plate 3 are inserted, and these pipes 7 and 8 and the top plate 3 are welded. In this welding, it is preferable to insert the tips of the pipes 7 and 8 into the top plate 3 and fillet weld the top plate 3 and the pipes 7 and 8 from the tip side of the pipes 7 and 8. Further, as a welding method, arc welding is preferably performed using a welding rod made of pure titanium, and more specifically, Tig welding using an inert gas as a shielding gas is preferably performed.

  Next, the rising portion 4 and the body portion 2 of the top plate 3 to which the pipes 7 and 8 are welded are butt-back welded, and the rising portion 6 of the bottom plate 5 is butt-back welded. The welding method in this case is also preferably arc welding such as Tig welding using a welding rod made of pure titanium.

  Thus, after assembling the top plate 3, the body 2, the bottom plate 5, and the pipes 7 and 8 into the storage container by welding, it is preferable to sequentially perform a cleaning process, a drying process, and an inspection process.

  In the cleaning step, for example, the storage container is filled with RO water, and ultrasonic cleaning is performed by applying ultrasonic waves of 19.5 kHz to 3 MHz for 5 to 180 minutes.

In the drying process, for example, when the capacity of the storage container is 50 L, first, oven drying (normal pressure, normal temperature to 100 ° C., 1 to 24 hours) is performed, and then vacuum drying (temperature: normal temperature) using a vacuum pump. ~ 100 ° C, pressure: 10 ^-4 Pa or less, 1 to 24 hours), then nitrogen blow drying (flow rate 1 to 5 L / min, flowing nitrogen gas (oxygen content less than 10 ppb, water content less than 120 ppb), 1-24 hours).

  Thus, it is possible to obtain a storage container having no particle or metal contamination and having improved cleanliness. When ozone gas is stored in this storage container, the attenuation amount of the ozone gas concentration is less than that of a conventional stainless steel ozone gas storage container. Become.

  In order to confirm that the storage container of the present invention is excellent in ozone gas storage performance, an ozone gas concentration attenuation test was performed as follows.

  That is, as shown in FIG. 4, an ozone generator 20 that generates ozone by electrolysis of water is connected to the pipe 7 of the storage container 1 (volume 50 L) via a valve, and the ozone concentration is measured by an ultraviolet absorption method. The ozone gas concentration meter 21 (Ebara Business Co., Ltd., PG-620 series) was connected to the pipe 8 of the storage container 1 via a valve.

Ultra pure water was supplied to the ozone generator 20 to generate an ozone-containing gas. When the gas concentration of the ozone-containing gas generated from the ozone generator 20 was measured, it was ozone 215 g / Nm ³ (ozone 10 vol%, nitrogen 90 vol%).

The ozone-containing gas generated by the ozone generator 20 is vented to the storage container 1 for 74 hours to replace the air in the container with ozone gas, and the concentration of the ozone-containing gas discharged from the storage container 1 after the passage of the ventilation 74 hours is determined. It measured with the ozone gas concentration meter 21. At this time, the ozone concentration was 214 g / Nm ³ .

Next, the ozone-containing gas supplied from the ozone generator 20 was sealed in the storage container 1 and held at room temperature for 16 hours. After holding for 16 hours, the ozone-containing gas was discharged from the storage container 1, and the ozone concentration in the discharged gas was measured with an ozone gas concentration meter 21. At this time, the ozone concentration was 04 g / Nm ³ .

  FIG. 5 shows the relationship between the ozone concentration thus measured and time. From FIG. 5, it can be seen that the ozone concentration in the ozone-containing gas is reduced only by 0.47 vol% with respect to the entire gas in the container even when held in the storage container 1 of the present invention for 16 hours.

  Further, in order to confirm that particles formed during welding did not remain in the storage container of the present invention, particles in nitrogen gas 1CF (cubic feet) passed through the storage container were measured with a particle counter. More specifically, clean nitrogen gas was sent to the storage container, and particles having a particle diameter of 0.1 μm or more contained in the gas 1CF discharged from the storage container were measured with a particle counter (PMS, HPGP-101). This measurement was repeated three times, but no particles having a particle size of 0.1 μm or more were detected.

DESCRIPTION OF SYMBOLS 1X Conventional ozone gas storage container 1 Storage container of 1 Example 2 Body part 3 Top plate 3a Corner | angular part of top plate 4 Rising part 5 Bottom plate 5a Corner | angular part of bottom plate 6 Rising part 7 Pipe (gas inlet)
8 Pipe (gas outlet)
10, 10b Welded part 11 Bead 12 Gap 13 Back wave part 14 Gap 20 Ozone generator 21 Ozone gas concentration meter t2, t4, t5

Claims (10)

A storage container having a top plate at one end of a cylindrical body, and a bottom plate at the other end, at least the inner surface of the storage container is formed of titanium, and the top plate and the bottom plate are in contact with the body part. A storage container which is welded and has a bead on the inner side of the storage container of which a pipe made of titanium at least on the inner surface is welded to the top plate as an inlet or outlet of the stored item .   The storage container according to claim 1, wherein the top plate and the bottom plate each have a rising portion on the outer peripheral portion, and the rising portion and the body portion are butt-welded and back welded.   The storage container according to claim 2, wherein an inner surface of the rising portion is rounded.   The storage container according to any one of claims 1 to 3, wherein particles having a particle diameter of 0.1 µm or more are not detected in 1 CF of nitrogen gas passed through the storage container. The storage container according to any one of claims 1 to 4 , for storing ozone gas. A method of manufacturing a storage container having a top plate at one end of a cylindrical body and a bottom plate at the other end,
Polishing the inner surface of the storage container of at least the cylindrical body, the top plate having the rising portion on the outer peripheral portion, and the bottom plate having the rising portion on the outer peripheral portion. Polishing process,
Inserting a pipe made of titanium at least on the inner surface of the top plate and welding the pipe and the top plate;
The manufacturing method of the storage container which has the process of butt-butting and welding a trunk | drum and a baseplate and a trunk | drum and a top plate, respectively.   The method for producing a storage container according to claim 6, wherein in the polishing step, the surfaces of the body part, the top plate and the bottom plate which are the inner surfaces of the storage container are chemically polished or electrolytically polished so that the surface roughness (Ra) is 0.14 µm or less.   The method for producing a storage container according to claim 7, wherein in the polishing step, buffing is performed prior to chemical polishing or electrolytic polishing.   Prior to the polishing step, the method includes a machining step of forming a cylindrical body, a top plate having a rising portion on the outer peripheral portion, and a bottom plate having a rising portion on the outer peripheral portion by cutting a titanium material. The manufacturing method of the storage container in any one.   The manufacturing method of the storage container according to claim 9, wherein in the machining step, the corners of the top plate and the corners of the bottom plate, which are the inner surfaces of the storage container, are rounded.

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