JP2000331980A - Bubbler and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bubbler which can reduce occurrence of chugging caused by accumulated dust, has high bonding power and a sufficiently high strength, and can be worked and enlarged easily. SOLUTION: A bubbler is composed of a bubbler base section 22, on which projecting air reservoir demarcating ribs 21 are provided, and a bubble lid section 23 and the sections 22 and 23 are made of modified polyterafluoroethylene which is a copolymer of tetrafluoroethylene and another monomer, with the content of the monomer being adjusted to such a unit quantity that does not give melt flowing property to the obtained modified polytetrafluoroethylene. After subjecting the base section 22 and lid sections 23 to preforming, baking, and cutting, the sections 22 and 23 are fused to each other through rebaking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bubbler and a method for producing the bubbler, and more particularly, to a bubbler suitable for dissolving, for example, ozone in water, and a method for producing the bubbler.

[0002]

2. Description of the Related Art Cleaning and stirring with ozone is indispensable for semiconductor wafers. Bubbler materials that generate air bubbles in such fields generally include chemical resistance,
Fluororesins having excellent properties such as heat resistance and permeation resistance are used. Fluororesin, which cannot be melt-molded such as PTFE (polytetrafluoroethylene), and P
They can be broadly classified into those which can be melt-molded, such as FA (polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer).

[0003] When producing a bubbler, in terms of productivity, a molten resin (such as PFA) that can be extruded and injection molded.
However, in terms of the above characteristics such as heat resistance, PTF
Since it does not reach E, those requiring such excellent characteristics are generally formed of PTFE. However, since PTFE cannot be injection-molded or the like,
Those with a complicated shape such as a bubbler cannot be integrally formed. Therefore, when producing a bubbler, it is manufactured by preparing a plurality of members preliminarily fired from a preform and joining them.

FIG. 7 shows an example of a conventional bubbler formed by joining a plurality of components made of PTFE.
The bubbler 1 is formed in a size of about 100 mm × 100 mm. The bubbler 1 includes a bubbler base 3 having stepped recesses 2 formed at predetermined intervals, and a bubbler lid 4 having a convex cross section for closing an open end of the base 3. It is formed in a shape.

[0005] Here, the bubbler base 3 and the bubbler lid 4 are manufactured by first molding these preforms and then firing the preforms. Then, these baked separate preforms are later cut and then joined to form a preform as shown in FIG.
The bubbler 1 as shown in FIG. Note that P
Since TFE has no self-fusing property, PFA having fusibility with PTFE is used for the joint 5 by welding.

On the other hand, as shown in FIG. 8 and FIG.
An FE bubbler 10 is also provided. The bubbler 10 comprises a bubbler base 7 having a dovetail groove 6 and a bubbler lid 9 having a dovetail 8 formed therein.
It is assembled integrally with the Toari 8. In such a bubbler 10 as well, a preformed preform is fired in a furnace and then cut, and thereafter, the joint 5 is
A welded.

[0007]

In recent years, there has been an increasing demand for semiconductor wafers requiring cleaning with ozone or the like, and accordingly, the size of a plant has been gradually increased. Accordingly, there is an increasing demand for larger bubblers. However, since the bubbler has a structure having a hollow portion that becomes an air reservoir inside, if the bubbler welded by PFA as described above is enlarged,
There are the following problems.

That is, PFA welding can be performed only from the outside, and the inside inside is not welded at all.
In addition, the strength of the joint 5 is weaker than other parts. Therefore, when the bubbler 1 as shown in FIG. 7 is further enlarged, the mechanical strength of the hollow inner portion is weaker than that of the outer portion at present. For this reason, when air bubbles such as ozone are generated, there is a problem that the welded portion is likely to gradually separate due to the internal pressure.

[0009] In addition, since the inner surface of a bubbler made of PTFE is usually cut after firing, the smoothness of the inner surface is generally deteriorated. Therefore, dust easily accumulates on the fine uneven surface, and clogging occurs in generating bubbles, which is a problem. On the other hand, in the case of the bubbler 10 shown in FIGS. 8 and 8, in addition to the fact that clogging is likely to occur, the fitting force between the dovetail groove 6 and the dovetail 8 can enhance the joining force, but the processing is difficult. It is complicated, especially when trying to form a large bubbler, a thin portion is formed, the strength is weak, and it is difficult to meet the demand for processing accuracy.

In the case of the bubbler 10, even if the whole is formed of a porous body, there is a hole 8 in the whole surface.
The substantial surface portion formed with is formed thick. Therefore, the bubbler 10 provided with the dovetail groove 6
In the case of (1), there is a problem in that the generation of bubbles varies between the thin portion and the thick portion. This means that the effective area of the bubbling surface when the size is increased is reduced.

Furthermore, in the case of the bubbler 10, the dovetail groove 6
The formation of the dovetail 8 causes a problem that the thickness of the whole bubbler becomes large, which not only increases the weight against weight reduction but also against compactness. In view of such circumstances, the present invention can exert sufficient strength even when the size is increased, reduce clogging due to dust accumulation, and furthermore, generate air bubbles uniformly from the surface. It is another object of the present invention to provide a bubbler and a method of manufacturing a bubbler which can exhibit the above characteristics even when the size and weight are reduced.

[0012]

According to a first aspect of the present invention, there is provided a bubbler having a bubbler body composed of two or more members, and an air pocket formed between the plurality of members. And at least one member is a porous body formed from modified polytetrafluoroethylene, and the modified polytetrafluoroethylene is a copolymer of tetrafluoroethylene and another monomer. The copolymer is characterized in that the amount of the other monomer units in the copolymer is small enough not to impart melt flowability to the resulting modified polytetrafluoroethylene.

According to the present invention, a bubbler having no welding portion can be provided. Further, the bubbler according to the present invention is characterized in that the bubbler main body is provided with a bubbler base portion provided with a plurality of ribs that define a plurality of communicating air reservoirs, and the bubbler base portion is mounted on the bubbler base portion. And a bubbler lid that defines the air reservoir between the parts, the bubbler base and the bubbler lid are a copolymer of tetrafluoroethylene and another monomer, and Is formed from a modified polytetrafluoroethylene copolymerized in such a small amount that does not impart melt flowability to the resulting modified polytetrafluoroethylene, and at least the bubbler lid is a porous material. Characterized by being formed from

According to such a configuration, the contact area in the inner side is increased by the rib, so that the bonding strength can be sufficiently increased. In the present invention, the porous body preferably further contains an inorganic filler, and more preferably, the inorganic filler is silica. When a hydrophilic inorganic filler represented by silica is blended, bubbles having a smaller bubble diameter can be generated from the bubbler. For example, by blowing ozone gas into the semiconductor cleaning liquid through the bubbler, the semiconductor The ozone gas concentration in the wafer cleaning liquid can be further increased, and the cleaning liquid can be stirred more uniformly.

Further, in the method for producing a bubbler according to the present invention, a copolymer of tetrafluoroethylene and another monomer is obtained, and another monomer unit amount in the copolymer is obtained. The modified polytetrafluoroethylene, which is a small amount that does not impart melt flowability to the modified polytetrafluoroethylene, corresponds to the bubbler base and the bubbler lid attached to the opening end surface of the bubbler base. Each of the preforms is molded, and after these preforms are primarily fired, the inner surface is cut, and the obtained molded body is subjected to a welding mold designed to have a size larger than the outer dimensions of the molded body. It is characterized in that a bubbler is formed by performing a re-firing treatment together with the fusion by using it.

According to such a configuration, it is possible to provide a bubbler having high dimensional accuracy and having no welding portion.
Here, of the preform, at least the bubbler lid is formed of a porous material. Further, in the method of manufacturing a bubbler according to the present invention, at least the preform of the porous body used in the bubbler lid is (i) a modified polytetrafluoroethylene powder obtained by a suspension polymerization method, A mixture with a pore-forming agent powder whose temperature is lower than the melting point of the modified polytetrafluoroethylene resin is formed by pressure molding,
(ii) The preformed product is formed into a porous body by heat-treating the preformed product at a temperature not lower than the decomposition temperature of the pore forming agent and not higher than the melting point of the modified polytetrafluoroethylene resin to decompose and remove the pore forming agent. It is characterized by.

According to such a method, the surface of the bubbler can be made porous, and ozone and the like can be diffused from the surface. In the present invention, in addition to the modified polytetrafluoroethylene powder and the pore-forming agent powder, the mixture for forming the preformed body of the porous body further contains an inorganic filler, preferably silica, for the same reason. It is desirable to be blended.

According to the present invention, a so-called modified PT
Due to the characteristics of the FE, it was found that the inner surface of the bubbler cut by re-firing becomes smooth. In addition, by re-firing, the surfaces are fused butted together without welding, and the joining surfaces of the ribs are also fused together, so that the strength can be greatly increased. As a result, according to the present invention, it is possible to reduce the number of places where particles easily accumulate as much as possible, to improve the dimensional accuracy, and to sufficiently increase the strength.

Therefore, according to the method of the present invention, it is possible to provide a bubbler which is suitably used for cleaning a semiconductor wafer or the like. In the second bubbler according to the present invention, the bubbler body is composed of two or more members, an air pocket is formed between the plurality of members, and at least one member is made of unmodified polytetrafluoroethylene. It is characterized by being a porous body formed from fluoroethylene and an inorganic filler. In a preferred embodiment, the inorganic filler is desirably a hydrophilic inorganic filler silica for the same reason as described above.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 (A),
(B) shows a bubbler 20 according to an embodiment of the present invention, which is formed in a size of about 400 mm × 250 mm. The bubbler 20 includes a bubbler base 22 having a bubbler body projecting a plurality of ribs 21, and a bubbler lid 23 attached to an opening end surface of the bubbler base 22.
It is composed of By attaching the bubbler lid portion 23 to the bubbler base portion 22, an air reservoir 24 communicating with each other is defined therebetween. And
Ozone introduced from the PFA tube 35 into the air reservoir 24 can emit cleaning bubbles.

The bubbler 20 is made of modified PTFE (polytetrafluoroethylene) having excellent heat resistance, chemical resistance and cleanliness. In addition, at least the bubbler lid 23 of the bubbler base 22 and the bubbler lid 23 is made of a porous material. When this modified PTFE is polymerized with tetrafluoroethylene, it is copolymerized with "another copolymerizable monomer" in such a small amount as not to give melt flowability to the homopolymer of tetrafluoroethylene. It is denatured. Such a modified PTFE does not have a melt fluidity like PTFE which is a homopolymer of tetrafluoroethylene,
Such a modified PTFE is obtained by copolymerizing tetrafluoroethylene and another copolymerizable monomer,
The other copolymerizable monomer is a small amount that does not give melt fluidity to the obtained modified PTFE, that is, a total of 100% of tetrafluoroethylene and other copolymerizable monomer.
In the mole%, another monomer is used, for example, at about 0.5 mole% or less. In other words, this modified PTFE is a copolymer in which tetrafluoroethylene units and other copolymerizable monomer units are arranged in an arbitrary order. The body unit is contained in such a small amount as described above, and has substantially no melt flowability like PTFE. Examples of such a copolymerizable monomer used in the production of modified PTFE include hexafluoropropylene, perfluoro (alkyl vinyl ether), perfluoro (alkoxyalkyl vinyl ether), trifluoroethylene, and perfluoroalkylethylene. You.

In order to form the bubbler 20 using such modified PTFE, first, as shown in FIG. 3, the raw material powder F is uniformly filled in the molds 25 and 26, and usually 300 to 500 kg. / Cm ^{2, and} the pressure is maintained for 0.5 to 10 minutes to obtain a flat plate. The obtained flat preforms 27 and 28 are respectively
26. Then, the taken out preformed bodies 27 and 28 are housed in the furnace 19, where the first firing is performed. At the time of sintering, in the furnace 19, the sintering temperature is raised at a constant speed, for example, to 355 ° C., and sintering is performed at that temperature until the sintering is completed uniformly over the whole, and the temperature of the furnace 19 is maintained at a constant speed. Cool down to room temperature to complete.

The compacts 27 'and 28' which have been first fired in the furnace 19 are once taken out of the furnace 19, and the inner surface and the like are cut. Thereby, the rib 21
A plurality of air pools 24 communicating with each other are formed therebetween. On the other hand, a dedicated mold 30 for fusing the molded bodies 27 ′ and 28 ′ subjected to the primary firing to each other is prepared, and these molded bodies 27 ′ and 28 ′ are placed in the mold 30 in the bubbler 2.
0 are combined with each other. As described above, when the molded body 27 ′ and the molded body 28 ′ are combined with each other, the large number of ribs 21 formed on the molded body 28 ′ (bubble base 22) form the molded body 27 (bubbler lid 23).
Is in contact with the inner surface.

After assembling in such a posture,
The exclusive mold 30 is again housed in the furnace 19, and in this furnace 19, the molded bodies 27 ′ and 28 ′ made of modified PTFE.
Is refired at, for example, 355 ° C., which is higher than the melting point of PTFE of 327 ° C., fusion of the contact surfaces between the two members occurs. That is, since the preformed bodies 27 and 28 are not only in the outer peripheral area of the opening end face but also in the inner rib tips all in contact with the inner wall surface, these preformed parts are all It will be fused. As a result, the bonding area between the bubbler base 22 and the bubbler lid 23 becomes extremely large as compared with the conventional example, and the bonding strength can be increased.

Here, the conditions for fusing will be described. First, a dedicated mold 30 is used for fusion. Further, if the dimensions of the mold 30 are made to coincide with the outer dimensions of the product, there will be no escape area for the increase due to the thermal expansion at the time of fusion, and the mold will be deformed after cooling. Therefore, the dimensions of the dedicated mold 30 are set to be 2 to 5% larger than the outer shape of the product, thereby preventing deformation at the time of fusion and obtaining appropriate dimensions.

The conditions for fusing in the furnace 19 after setting the special mold 30 in the furnace 19 are, for example, as shown in FIG.
As shown in FIG. That is, first, the room temperature is 25 ° C.
And heated to 355 ° C., which is higher than the melting point of PTFE of 327 ° C., over a period of 5 hours, and kept at that state for 5 hours.
C). The pressure at this time is 50 gf / cm ² with respect to the fused area.

Under such conditions, the molded body 28 'of the primary-fired bubbler base 22 made of modified PTFE and the molded body 27' of the primary-fired bubbler lid 23 as shown in FIG. Are fused together. Moreover, the obtained bubbler 20 was excellent in dimensional accuracy and could be formed into a desired shape. In the bubbler 20 made of modified PTFE manufactured in this way, since the re-firing is performed simultaneously with the fusion, the cut surface after the surface treatment is compared with that before the surface treatment of the modified PTFE. Were alleviated and smoothness was provided.

Therefore, the inner surfaces of the bubbler base portion 22 and the bubbler lid portion 23 are excellent in surface smoothness, and even when the chemical solution comes into contact, the surfaces are smooth.
Dust and the like do not remain on the surface, and are excellent in cleanliness. In addition, modified PTFE has excellent chemical resistance such as resistance to permeation of gases and chemicals, and has little elution of impurities. Therefore, it is very suitable for a bubbler for cleaning semiconductors. In addition, the size of the bubbler 20 can be freely set, and the bubbler 20 can be provided according to dimensions.

In the above embodiment, the bubbler 20 is a modified PT
Although the aspect formed from the FE has been described, in the present invention, among the bubbler base portion 22 and the bubbler lid portion 23 constituting the bubbler, a member composed of at least a porous body, for example, for the bubbler lid portion 23 The material of
It is desirable that an inorganic filler be contained. As inorganic fillers, silica, glass (glass beads), bronze,
Calcium carbonate, boron trinitride, white carbon,
Potassium titanate fiber, zinc oxide, carbon fiber, alumina, talc, tin oxide, graphite and the like can be mentioned. In particular, for a bubbler used in an environment where corrosion resistance is required, among the above-mentioned inorganic fillers, silica, titanium, glass fiber, quartz, and the like having excellent corrosion resistance are preferably used. These inorganic fillers can take various known shapes such as a fibrous shape and a powdery shape, but a powdery shape is preferable. The average particle size of these powders is usually 2 to 30 μm, preferably 5 to 30 μm.
It is desirable that the thickness be 15 μm. Powder of the fiber,
For example, for powders such as potassium titanate fiber and carbon fiber, the aspect ratio (fiber length / fiber diameter) is usually 4 to 150, preferably 4 to 10.

Further, such inorganic fillers include, for example,
Total 10 of modified PTFE and inorganic filler in porous member
Usually, 5 to 75 parts by weight, preferably 8 parts by weight based on 0 parts by weight.
It is desirable that the content is contained in the porous member or the like in an amount of 50 to 50 parts by weight, particularly preferably 10 to 20 parts by weight. In a bubbler in which such an inorganic filler is preferably added in the above amount, the surface becomes hydrophilic, and bubbles (gas) having a smaller bubble diameter can be efficiently and easily generated from the bubbler. As a result, For example, the concentration of dissolved gas such as ozone gas in the semiconductor wafer cleaning liquid can be further increased, the cleaning liquid can be efficiently stirred, and the components can be more uniformly dispersed and mixed.

In the above embodiment, the preform 27,
28 is formed from a porous body in advance.
A method for converting these preforms into a porous body will be specifically described. Method for Producing Porous Body Made of Modified PTFE (i) In this example, first, the modified PT obtained by the suspension polymerization method was used.
A mixture of FE powder and powder of a pore-forming agent having a decomposition temperature lower than the melting point of the modified polytetrafluoroethylene resin is molded to prepare a preform.

In this embodiment, a modified PTFE powder obtained by a suspension polymerization method is used. This modified PTFE powder is
It is desirable that the average particle size be 1 to 900 μm. The number average molecular weight of these modified PTFE is 2,000,000 to 200,000.
It is desirably about 100,000, preferably about 4,000,000 to 8,000,000. As the pore-forming agent having a decomposition temperature lower than the melting point of the modified polytetrafluoroethylene resin, an organic foaming agent and an inorganic foaming agent are preferably used.

As the organic foaming agent, a commercially available one can be used. Examples of the inorganic foaming agent include ammonium hydrogen carbonate, ammonium carbonate, and ammonium nitrite. Two or more such pore-forming agents can be used in combination. In this embodiment, it is particularly preferable to use at least one selected from ammonium bicarbonate, ammonium carbonate and ammonium nitrite as the pore-forming agent.

The powder of such a pore-forming agent preferably has an average particle size of 1 to 500 μm. The particle size of such a pore-forming agent powder is preferably closer to the particle size of the modified PTFE powder to be mixed, because it can be uniformly mixed with the modified PTFE powder. The pore-forming agent powder is decomposed by a heat treatment described later to generate pores in the molded body. Further, it is possible to control the pore size of the modified PTFE porous molded body by the particle size of the pore-forming agent powder,
For example, when the particle size of the pore-forming agent powder is small, a modified PTFE porous compact having a small pore size can be obtained.

Such a pore-forming agent powder can be obtained by pulverizing a commercially available pore-forming agent such as ammonium bicarbonate. As a method for pulverizing the pore-forming agent, a conventionally known method can be employed. The method of mixing the modified PTFE powder and the pore-forming agent powder is not particularly limited, and examples thereof include a dry mixing method such as a Henschel mixer, a high-speed mixer, and a super mixer, and a wet mixing method such as mixing in a slurry state.

The mixing ratio of the modified PTFE powder and the pore-forming agent powder (modified PTFE: pore-forming agent weight ratio) is 0.5: 9.5 to 9.5.
It is desirable that the ratio is 9.5: 0.5, preferably 1: 9 to 7: 3. From the mixture of the modified PTFE powder and the pore-forming agent powder mixed at this mixing ratio, it is possible to produce a modified PTFE porous molded body having a controlled porosity. For example, if the ratio of the pore-forming agent is increased, In addition, the porosity of the molded body can be increased.

Such a mixture contains the modified PTFE described above.
Various additives other than the powder and the pore-forming agent powder may be blended. Examples of the additive include a lubricant, a pigment, and the above-mentioned inorganic filler. In the present invention, a mixture of the above-mentioned modified PTFE powder, a pore-forming agent powder, and additives such as an inorganic filler compounded as required is molded to prepare a preform.

As a molding method, for example, 50 to 500 k
Examples include a method of compression molding at a pressure of g / cm ² , a ram extrusion molding method, and the like. The specific conditions of the pre-molding are appropriately selected depending on the molding method to be used, the type of the molding machine, the mixing ratio of the modified PTFE powder and the pore-forming agent powder, the shape, size, and porosity of the target porous molded body. Is done.

(Ii) Next, the preform is heat-treated at a temperature not lower than the decomposition temperature of the pore-forming agent and not higher than the melting point of the modified polytetrafluoroethylene resin to decompose and remove the pore-forming agent in the molded body. As such a heat treatment temperature, specifically, 4
It is desirably 0 to 300 ° C, preferably 60 to 150 ° C.

The heat treatment time depends on the size and thickness of the molded body, but is preferably several seconds to 200 hours, preferably 1 to 50 hours. Modified P after decomposition and removal of pore former
The TFE molded product is fired at a temperature equal to or higher than the melting point of the modified polytetrafluoroethylene. Specifically, as the firing temperature,
It is desirably 330 to 380 ° C, preferably 360 to 380 ° C.

After calcination, the obtained porous body made of modified PTFE is cooled by a slow cooling method such as standing, or a rapid cooling method such as water cooling or air cooling. By such heat treatment, the pore-forming agent is thermally decomposed, so that the modified PTFE containing few impurities is used.
A porous body can be obtained. According to the production method according to the present invention as described above, a modified PTFE porous body having a density of 0.2 to 2 g / cm ³ and a porosity of 10 to 90% can be obtained.

The porous body made of modified PTFE thus obtained has a low dielectric property, for example, a porosity of 40%.
In this case, the relative dielectric constant is 1.5, and when the porosity is 70%, the relative dielectric constant is 1.2. Further, the porosity is 20 to 5
When a 0% modified PTFE porous body is used as a bubbler, fine bubbles can be obtained. Therefore, it is useful as a bubbler for dissolving ozone gas in water or for stirring a chemical solution in the field of semiconductors and the like.

The modified PTF thus obtained is
Since the surface of the porous body made of E was in contact with the mold at the time of manufacture, pores on the surface of the porous body may be crushed. In such a case, in order to use as a bubbler, the surface of the porous body may be cut to expose the porous surface. In such a porous body that has been surface-cut, the inorganic filler that is exposed to the surface of the porous body with the cutting process and adheres in an unstable state may fall off or peel off. For example, by performing bubbling for about 24 hours, the inorganic filler that has adhered to the surface of the porous body in an unstable state hardly disappears, and can be favorably used as a bubbler.

In the above description, the case where a porous body made of modified PTFE is produced from a mixture of the modified PTFE powder obtained by the suspension polymerization method, the pore-forming agent powder, and the inorganic filler used as required. As described above, in the present invention, as long as the above-mentioned inorganic filler is contained, a (non-modified) PTFE porous body may be used instead of the modified PTFE porous body. Also in that case, the inorganic filler is the modified PT
It is used in the same amount as in the case of the porous body made of FE.

In a bubbler in which such an inorganic filler is blended in a porous body, the surface of the bubbler becomes hydrophilic,
Bubbles (gas) having a smaller bubble diameter can be efficiently and easily generated from the bubbler. As a result, for example, the concentration of a dissolved gas such as ozone gas in a semiconductor wafer cleaning solution provided with the bubbler can be further increased. Further, the washing liquid can be efficiently stirred, and the various components can be more uniformly dispersed and mixed in the washing liquid.

An example of such a bubbler is shown in FIGS. 6A and 6A described later. The bubbler according to the second embodiment of the present invention shown in FIGS. 6 (A1) and (A2) has a cylindrical shape,
A mixture of unmodified PTFE, unmodified PTFE, a pore-forming agent powder, an inorganic filler and the like,
A cylindrical member is formed from a TFE porous body.

The method for producing such an unmodified porous PTFE material is the same as that described in Japanese Patent Application Laid-Open No. HEI 10-260, which was previously proposed by the applicant of the present invention, except that a raw material containing an inorganic filler preferably in the above amount is used as a raw material. The method described in Japanese Patent Application No. 11-124458 (Japanese Patent Application No. 9-289954) may be employed. As described above, one embodiment of the present invention has been described.
The present invention is not limited to the above embodiments.

For example, in the embodiment shown in FIG. 1, the bubbler 20 is constituted by two members, the bubbler base portion 22 and the bubbler lid portion 12. However, for example, the bubbler is constituted by three or more members. You can also. Further, both the bubbler base portion 22 and the bubbler lid portion 23 need not be porous, but at least one of them is only required to be porous. The shape and number of the ribs 21 are not limited at all. In short, what is necessary is just to form the air pocket 22 inside.

For example, in the bubbler of the present invention (the bubbler of the second embodiment), one end is sealed and the other end is opened as shown by reference numeral 20A in FIGS. 6 (A1) and 6 (A2). Alternatively, a gas may be supplied to the inside of the bubbler 20A from a gas supply pipe 42 which is formed of a cylindrical porous body and joined to the open end side. As described above, the bubbler 20A of the second embodiment is made of, for example, PTFE (unmodified PTFE) containing silica or the like. Such a bubbler is manufactured by the following method.

For example, (i) an inorganic filler represented by silica, a polytetrafluoroethylene powder obtained by a suspension polymerization method, a pore-forming agent powder having a decomposition temperature lower than the melting point of the polytetrafluoroethylene resin. (Ii) heat treatment at a temperature not lower than the decomposition temperature of the pore-forming agent and not higher than the melting point of the polytetrafluoroethylene resin. After the pore agent is decomposed and removed, (iii) the molded product is formed by cutting from a columnar material obtained by firing at a temperature equal to or higher than the melting point of polytetrafluoroethylene. The outer dimensions of the bubbler 20A are, for example, 50 mm × 22 mm (outer diameter).
The depth of the air pocket inside the bubbler is 44 mm (wall thickness at the bottom of the bubbler is 6 mm).

For example, in the bubbler of the present invention (the bubbler of the third embodiment), as shown by reference numeral 20B in FIGS. 6 (B1) and 6 (B2), the bubbler base 32 has no ribs. It has a square box shape and a bubbler lid 33
May be formed of a plate-shaped porous body, and a gas supply hole 40 may be provided on a side wall of the bubbler base 32. The outer dimensions of the bubbler 20B are, for example, 100 mm long × 100 mm wide × 20 mm high, and the air pocket inside the bubbler is 90 mm long × 90 mm wide × 10 mm deep.

The bubbler according to the third embodiment has, for example, a modified PTF in which the lid is made of silica or the like.
E and the bubbler base is made of (silica-free) modified PTFE obtained in the manner described above. In the bubbler of the present invention as described in detail above, when the porosity is the same, regardless of its shape, whether the resin is unmodified PTFE or modified PTFE
In any case, as the filler content in the bubbler increases, the bubble diameter generated from the bubbler decreases, for example, the amount of dissolved gas in the semiconductor processing solution equipped with the bubbler increases. Tend. Also, when the gas blowing time is long, the amount of dissolved gas in the semiconductor processing solution tends to increase.

[0053]

As described above, according to the present invention,
By using the modified PTFE porous body, it is possible to provide a bubbler having no welding portion. Also,
The modified PTFE porous body can be manufactured by a simplified manufacturing process. In addition, when the modified PTFE porous body contains the inorganic filler represented by silica (preferably in the amount described above), the bubble diameter becomes smaller, and the semiconductor processing liquid into which gas is blown is used. And the like can increase the amount of dissolved gas in the solution.

The same effect as described above can be obtained even when the above-mentioned inorganic filler is contained in the unmodified porous PTFE material. Further, by refiring the modified PTFE, the cut surface can be smoothed, so that a bubbler without clogging can be provided. further,
When the modified PTFE is refired, fusion can be performed at the same time, so that a bubbler having no welded portion can be provided. In addition, at the time of fusion by re-firing, not only the outer peripheral surface but also the tip portion of the rib provided on the bubbler lid can be fusion-bonded, so that even if the size is increased, the mechanical strength is extremely high. High bubbler can be provided.

As described above, according to the bubbler of the present invention, clogging hardly occurs even when the size is increased.
A compact and lightweight bubbler having sufficient strength can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a bubbler according to an embodiment of the present invention.

FIG. 2 is a sectional view of the bubbler shown in FIG. 1;

FIG. 3 is a schematic diagram showing a simplified method according to the invention.

FIG. 4 is a graph showing conditions for refiring in the method according to the present invention.

FIG. 5 is a cross-sectional view of a bubbler according to one embodiment of the present invention.

FIG. 6 (A1) is a longitudinal sectional view of a bubbler according to a second embodiment of the present invention, and FIG. 6 (A2) is a transverse sectional view thereof. FIG. 6 (B1) is a longitudinal sectional view of a bubbler according to a third embodiment of the present invention, and FIG. 6 (B2) is a transverse sectional view thereof.

FIG. 7 is a sectional view showing a conventional bubbler.

FIG. 8 is an exploded perspective view showing another conventional bubbler.

FIG. 9 is a sectional view of the bubbler shown in FIG. 8;

[Explanation of symbols]

 20, 20A, 20B Bubbler 22, 32 Bubbler base 23, 33 Bubbler lid 27, 28 Preformed body 19 Furnace 30 Dedicated mold 40 Gas supply hole 42 Gas supply pipe 44 Joint

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukihiko Tsuda 232-1 Tanasawa, Atsugi-shi, Kanagawa Prefecture Within the Research and Development Department, Functional Plastics Division, Nippon Baluka Industry Co., Ltd. (72) Inventor Yuji Kanai Atsugi, Kanagawa Prefecture 232-1 Tanazawa Ichi, Research and Development Department, Functional Plastics Division, Nippon Balkar Industry Co., Ltd.

Claims (10)

[Claims] 1. A bubbler body is composed of two or more members, an air pocket is formed between the plurality of members, and at least one member is a porous body formed of modified polytetrafluoroethylene. And the modified polytetrafluoroethylene is a copolymer of tetrafluoroethylene and another monomer, and the amount of the other monomer units in the copolymer is the modified polytetrafluoroethylene obtained. A bubbler characterized in that the amount is small enough not to give melt flowability to ethylene. 2. A bubbler base, wherein said bubbler main body is provided with a plurality of ribs which define a plurality of communicating air reservoirs, and said bubbler base is mounted on said bubbler base to form a gap between said bubbler base. A bubbler lid that defines the air pocket, wherein the bubbler base and the bubbler lid are a copolymer of tetrafluoroethylene and another monomer,
Other monomer units in the copolymer are formed from modified polytetrafluoroethylene, which is in such a small amount that does not impart melt flowability to the resulting modified polytetrafluoroethylene, and at least the bubbler lid The bubbler according to claim 1, wherein the portion is formed of a porous body. 3. The bubbler according to claim 1, wherein the porous body further contains an inorganic filler. 4. The bubbler according to claim 3, wherein said inorganic filler is silica. 5. A copolymer of tetrafluoroethylene and another monomer, wherein the other monomer is in such a small amount that it does not impart melt flowability to the resulting modified polytetrafluoroethylene. The preforms corresponding to the bubbler base and the bubbler lid attached to the opening end face of the bubbler base are formed by the modified polytetrafluoroethylene copolymerized in After the primary firing, the inner surface is cut, and the obtained molded body is subjected to re-firing together with fusion using a fusion mold designed to have a size larger than the outer dimension of the molded body, and the bubbler is subjected to bubbler processing. Forming a bubbler. 6. A preform of a porous body used for at least the bubbler lid, comprising: (i) a modified polytetrafluoroethylene powder obtained by a suspension polymerization method; A mixture with a pore-forming agent powder having a melting point lower than that of the resin is formed by pressure molding. The method for producing a bubbler according to claim 5, wherein the porous material is formed by decomposing and removing the pore forming agent by heat treatment. 7. The mixture for forming a preformed body of the porous body further comprises an inorganic filler in addition to the modified polytetrafluoroethylene powder and the pore former powder. The method for producing a bubbler according to claim 6. 8. The method for producing a bubbler according to claim 7, wherein the inorganic filler is silica. 9. A bubbler body is composed of two or more members, an air pocket is formed between the plurality of members, and at least one member is formed of polytetrafluoroethylene and an inorganic filler. A bubbler characterized by being a porous body. 10. The bubbler according to claim 9, wherein said inorganic filler is silica.