JPH10273193A - Large-sized container for transport of high purity chemical - Google Patents

Abstract

PROBLEM TO BE SOLVED: To circulate-filter a chemical by a filter, and keep the chemical in a container clean by arranging the filter, a liquid feeding pump and a piping in the container. SOLUTION: A piping 2, a liquid feeding pump 3, and a filter 4 are connected to a container 1, and a piping 5 is connected to the outlet from the filter 4 so that a chemical may be returned to the container 1, and an opening/closing valve is provided at respective places when necessary. In this case, the pipings 2, 5 are provided at locations lower than the chemical liquid surface in a tank, and useless air bubbles are suppressed from generating. In addition, at the outlet from the filter 4 and the piping returning to the container 1, a valve 6 and a branch piping 7 are provided, and used when the chemical is discharged from the container 1. By such a constitution, the liquid feeding pump 3 is driven when necessary, and by circulate-filtering the high purity chemical in the container 1, the high purity chemical is always kept clean.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large container for transporting chemicals for the electronics industry used in the semiconductor manufacturing field.

[0002]

2. Description of the Related Art In the field of the electronics industry, various high-purity chemicals are used for manufacturing semiconductors and liquid crystal display devices.
For example, high-purity hydrogen peroxide solution, high-purity ammonia water, high-purity tetramethylammonium hydroxide aqueous solution, high-purity sulfuric acid, high-purity hydrofluoric acid, and the like. The presence of a trace amount of impurities or fine particles in these chemicals adversely affects the device characteristics of semiconductor elements and liquid crystal display devices, and therefore, the chemicals must be of high purity. The purity required is extremely high, for example, the total metal is 1 ppb or less, and foreign matter having a size of 0.2 μm or more, that is, 100 particles / ml or less. For this reason, elution of impurities and generation of particles from the material of the container must be strictly controlled.

In general, containers and tank trucks having a capacity of several hundred kg or more are used for transporting a large amount of chemicals. When such a container is used, elution of impurities such as metals from the container is small, but particles may be generated in an unacceptably large amount, which is a problem. Even if all the particles are made of metal, 100 particles / ml of 0.2 μm or more correspond only to the sub-ppt as the metal concentration. Therefore, particle management must be performed much more strictly than elution of impurities such as metals.

[0004] When a chemical solution manufacturer fills a container with a chemical solution and transports it to a use point, particles are further generated from the container due to vibration or the like due to the transportation, and mixing into the chemical solution is promoted. In recent years, the use of high-purity chemicals overseas has increased,
There are many opportunities to transport from Japan to the country, but the longer the transport time and transport distance, the greater the amount of particles mixed in from the container. For this reason, at present, when a large container is used to transport a high-purity chemical solution, it has been extremely difficult to cleanly manage the chemical solution.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a large container for transportation which can provide a clean chemical solution when a high-purity chemical solution is used in a container filled with the high-purity chemical solution.

[0006]

Means for Solving the Problems As a result of intensive efforts, the present inventors have found that the chemical solution in the container can be kept clean by circulating and filtering the chemical solution in the container during transportation or storage. The invention has been reached.

That is, the present invention comprises a container body 1, a filter 4, a liquid feed pump 3 and a pipe, and the filter, the liquid feed pump and the pipe are arranged so as to circulate and filter the chemical in the container with the filter. The present invention relates to a large container for transporting a high-purity chemical solution.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to FIG. The vessel 1 is connected with a pipe 2, a liquid feed pump 3, and a filter 4. Further, a pipe 5 is connected to the outlet from the filter 4 so as to return to the container 1. An on-off valve may be provided at each location as needed.

By driving the liquid feed pump in such a form as required, the high-purity chemical in the large container can always be kept clean. There is no limitation on the number of times of filtration and the period. That is, filtration may be performed continuously or intermittently while the large container is being transported or left. Further, when using a high-purity chemical solution, filtration may be performed immediately before extracting from the container.

Here, there is no limitation on the connection positions of the pipes 2 and 5 to the tank. However, the pipe 2 must be provided below the surface of the chemical solution in the tank, and the pipe 5 is also preferably provided below the surface of the chemical solution in order to suppress generation of unnecessary bubbles.

Further, a valve 6 and a branch pipe 7 may be provided at the outlet from the filter 4 and the pipe returning to the container 1.
In this case, the branch pipe 7 can be used when extracting the chemical from the container. At this time, the chemical solution in the container is passed through the filter 4 and the branch pipe 7 by operating the liquid sending pump 3,
The chemical solution may be extracted by pressurizing the inside of the container with a pressure-feeding gas such as high-purity nitrogen or the like. Further, a pump outside the system may be installed at the end of the branch pipe 7 and extracted.

[0012] There is no limitation on the filtration flow rate per unit time. However, in the case of performing circulating filtration, the filtration is performed at a flow rate sufficient to sufficiently clean the chemical solution in the large container within the time, taking into account the time required for the filtration.

There are no restrictions on the materials of the large container, filter, piping, and liquid feed pump. However, it is necessary to use a material that has extremely little elution of impurities even when those liquid contact portions come into contact with a high-purity chemical solution. For example, fluorine resins such as polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), and tetrafluoroethylene / perfluoroalkylvinyl ether copolymer (PFA) are preferably used. In addition, those obtained by lining these resins may be used.

There is no limitation on the system of the liquid sending pump. A so-called bellows pump or a centrifugal pump may be used. However, since the elution of impurities and the generation of particles are small, the bellows method is preferably used.

A filter having an average pore size of 0.1 μm or less is used. In defining the pore size of the filter, a method using polystyrene latex standard particles is used. As polystyrene latex standard particles,
For example, those manufactured by Dow Chemical Co., Ltd. and Nippon Synthetic Rubber Co., Ltd. are used. In this method, ultrapure water in which polystyrene latex standard particles having different average diameters are dispersed is passed through the filters, and the turbidity of the ultrapure water before and after the passage is measured by UV light. Ask for. In the passage test, a plurality of standard particles having different average diameters are sequentially passed. 7 for the first time
The average diameter at the time of exceeding 0% is defined as the average pore size of the filter.

There is no limitation on the shape of the filter. That is, flat membrane, pleated type, spiral type, hollow fiber type, etc.
Any shape may be used. Further, regarding the filters, a plurality of filters having different pore diameters may be arranged in series in ascending order of the average pore diameter to remove particles in the chemical solution step by step.

[0017]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. In addition, KL-20 manufactured by Rion by a method utilizing laser light scattering was used for measuring the amount of particles.

EXAMPLE A large container for transportation as shown in FIG.
Eight tons of 1% by weight high purity hydrogen peroxide solution was filled. The number of particles in the hydrogen peroxide solution at the time of filling was 5 μm / ml at 0.2 μm or more. The filter has an average pore size of 0.
The filter was a 1 μm filter, and the pump was a bellows type pump. In addition, all the liquid contact portions of the hydrogen peroxide solution including the container were PFA.

The container was transported over a distance of 2000 km over a period of 3 days. During the transportation, the pump was always started, and the circulation filtration was continued. After transport, the hydrogen peroxide solution was extracted from the large container, and the number of particles having a particle size of 0.2 μm or more was measured. As a result, it was 10 particles / ml.

COMPARATIVE EXAMPLE The same operation as in the example was carried out except that a large vessel in which the apparatus according to the present invention such as the filter 4, the pump 3, and the pipe 2 was not installed in FIG.
The number of particles having a particle size of 0.2 μm or more in the hydrogen peroxide solution after transportation was 300 / ml.

[0021]

As described above, by using the large container of the present invention, a clean chemical solution can be provided without being affected by particles generated from the container when storing and transporting a high-purity chemical solution.

[Brief description of the drawings]

FIG. 1 is a large container for transporting a high-purity chemical solution of the present invention.

[Explanation of symbols]

 1: Container body 2: Piping 3: Liquid pump 4: Filter 5: Piping 6: Valve 7: Branch piping

Claims (2)

[Claims] 1. A container comprising a container body 1, a filter 4, a liquid sending pump 3 and a pipe, wherein the filter, the liquid sending pump and the pipe are arranged so as to circulate and filter the chemical solution in the container with the filter. Large container for transporting high-purity chemicals. 2. The large container for transporting a high-purity chemical according to claim 1, wherein the filter has an average pore size of 0.1 μm or less.