JPH0730875B2 - How to fill a pressurized transfer tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a highly clean and highly pure chemical liquid such as isopropanol (hereinafter referred to as IPA) used for cleaning electronic products such as ICs (integrated circuits). ) And the like are connected to a pressure type transfer tank and injected to fill the tank.

[Prior Art] Various chemical liquids such as alcohols such as IPA, ketones such as acetone and ethers such as isopropyl ether are used for cleaning IC substrates (silicon wafers). In addition to cleaning, chemical liquids are also used as solvents for chemical treatment agents.

The degree of integration of ICs has further increased, and along with this, various quality improvement requirements have been made for chemical liquids as cleaning agents for electronic components such as IC substrates.

That is, (a) a high-purity chemical liquid is desired in order to prevent the adverse effects of impurities. For example, the purity is 99.9
High purity of 9% or more is required.

(B) Do not contain metal components such as iron that may adversely affect the silicon wafer. This is for example ppb
Regulated by level.

(C) It is required that the chemical liquid does not contain insoluble solid fine particles such as dust, that is, it must be a highly clean chemical liquid. This is not preferable because solid fine particles become an obstacle when processing a fine circuit on a silicon wafer.

By the way, a high-purity chemical liquid containing no metal can be achieved to some extent by distillation or other refining means.

However, it is difficult to achieve the requirement for the above-mentioned ¹⁰ solid fine particles because the regulations are strict.

That is, for example, even if a clean chemical liquid containing no solid fine particles can be produced, it is impossible to prevent the fine particles from being mixed in the atmospheric environment due to a loading operation when actually shipping the liquid for transportation. The demands on these are so severe that even the inclusion of such fine particles and floating components in the atmosphere must be prevented. Iron, etc. is mixed in by contact with the air and even the purity is reduced.

Conventionally, the work of loading a high-cleanliness / high-purity chemical liquid has been performed in a so-called clean room in which the cleanness is specially adjusted. Therefore, the shipping form of the chemical liquid uses a small-scale small container such as a drum.

In recent years, however, the demand for chemical liquids in the electronic industry has increased, and it has become necessary to mass-ship large-scale containers such as lorries (tank lorries) and condiners.
It is not realistic to use the above-mentioned clean room for the filling operation into such a large container, and therefore, the development of an original filling method is desired.

[Problems to be Solved by the Invention] The present invention provides a method of filling a chemical liquid of high cleanliness and high purity into a large pressure type transfer tank such as a lorry tank or a container while maintaining its quality. With the goal.

[Means for Solving the Problems] The above-mentioned object of the present invention is to extract the chemical liquid from a nitrogen-sealed storage tank for storing high-purity chemical liquid having low cleanliness and to continuously use the primary and secondary filters. A high-purity chemical liquid that has been filtered to a predetermined degree of cleanliness is used as a filter-side flow path changing mechanism, flexible tube, joint, pressure-type moving tank filling port, pressure-type moving tank-side flow path changing mechanism, and hatch side valve. A method for filling a tank with a high-purity chemical liquid having a predetermined high cleanliness by sequentially injecting it into a plurality of hatches of a pressurization type transfer tank via (a) clean nitrogen in the flexible tube. While discharging nitrogen from the joint at the end of the tube to the outside, connect the joint to the filling port of the pressure type transfer tank, and (b) clean nitrogen The chemical liquid in the tank, which is saturated with nitrogen by bubbling into the storage tank, is continuously filtered with the filter to have high cleanliness, and a filter-side flow path changing mechanism and a flexible device provided after the filter are provided. By sending out the chemical liquid through the tube, (c) the chemical liquid sent out is returned to the tank through the return pipe from the pressurizing transfer tank side flow passage changing mechanism provided in the pressurizing movement tank side filling port. By circulating the chemical liquid, and (d) thereafter, closing the tank-side flow path changing mechanism for pressurization type movement, and instead returning the chemical liquid from the filter-side flow path changing mechanism to the tank via a return pipe line. While circulating the chemical liquid, the pressurized type moving tank side flow path changing mechanism is provided in the pressurized type moving tank while being electrically connected to the lorry filling port. Open the hatch side valve of one hatch, and (e) then gradually operate the filter side flow path changing mechanism to stop the circulation of the chemical liquid, and at the same time, to bring the flexible tube and the pressure-type transfer tank side flow into conduction. The chemical liquid is injected and filled from the hatch through the passage changing mechanism and the hatch side valve, and (f) when the injection of the predetermined amount of the chemical liquid into the one hatch is completed, the filter side flow passage changing mechanism is installed. By operating, the chemical liquid is circulated again by returning the chemical liquid from the flow path mechanism to the storage tank via the return conduit, and (g) closing the hatch side valve during the circulation of the chemical liquid. Then, the other hatch-side valve is opened to switch to the other hatch, and then the circulation is stopped by gradually operating the filter-side flow path changing mechanism. A chemical liquid is injected into the hatch of the ground, and the chemical liquid is sequentially filtered from a plurality of hatches of the pressurized transfer tank by blocking the contact with the atmosphere while continuously performing the filtration of the filter. It is achieved by a method of filling a tank for pressurized transfer by pouring into.

[Function] The chemical liquid of the present invention is a chemical liquid that is liquid at room temperature, and examples thereof include alcohols such as IPA, ketones such as acetone, ethers such as isopropyl ether, and petroleum fractions such as xylene. .

Examples of the pressurizing type transfer tank include a tank mounted on a lorry and a large tank such as a container.

The interior of each of these large tanks is divided into multiple chambers from the viewpoint of disaster prevention, and a hatch (mouth) for injection is installed in each chamber.

The present invention will be described below with reference to the accompanying drawings, taking as an example the case where IPA is filled in a lowry tank as a pressurization type transfer tank.

The storage tank 1 becomes highly pure by being distilled in a distillation column (not shown) and contains iron and other metal components.
IPA reduced to b level is stored.

The storage tank is sealed from the outside air by being sealed with clean nitrogen. In addition, IPA is saturated with nitrogen by bubbling nitrogen cleaned in the tank through the filter from the line 2 into the tank.
By doing so, it is possible to prevent the internal pressure from decreasing due to absorption of nitrogen after the tanker tank is filled with IPA.

In other words, if nitrogen bubbling in the tank is stopped and IPA is injected and filled into the tank truck without saturating with nitrogen, the internal pressure of the tank will be the first 1k after transporting for 3 hours with this tank truck.
It drops from g / cm ² (gauge pressure), and the internal pressure almost disappears.

However, in the case of IPA saturated with nitrogen, almost no decrease in internal pressure was observed.

It is necessary to pressurize the tank truck with nitrogen in order to block contact with the outside air, and it is difficult to replenish nitrogen from the outside even if the internal pressure of the tank is lowered because the tank is mounted on a vehicle.

Since the tank 1 is a storage tank for IPA as a product, there is no step after this tank for heating IPA such as distillation to release dissolved nitrogen. Also, bubbling of nitrogen is advantageous because it is an easy process to saturate. Therefore, it is convenient to saturate the nitrogen in tank 1.

Further, the tank 1 may be sealed with nitrogen, but can be pressurized if necessary. It is also a storage item
The material of the inner wall surface of the tank 1 is usually preferably stainless steel or steel coated with a synthetic resin such as Teflon so as not to dissolve metals in the IPA. Of course, it is not limited to this. In addition, such consideration is IP
It is also necessary at all points where A or its vapor comes into contact, such as the pumps described below, IPA delivery lines, various valves, flexible tubes, and tank trucks.

The tank is provided with a primary filter 3 and a secondary filter 4 in the middle of the delivery line via a delivery non-seal type pump. Not only the coarse particles in the IPA,
Since it is necessary to capture even extremely fine particles, the primary filter 3 is provided as a prefilter. The secondary filter 4 alone is not preferable because the filter will be clogged in a short period of time, the frequency of expensive filter replacement will be high, and the cost will increase. If necessary, more stages may be provided.

It is also necessary to select a material for the filters 3 and 4 that does not elute foreign matter in IPA.Chemical or physical so that foreign matter does not elute when polypropylene, Teflon, etc. come into contact with IPA as needed. A filter made of treated synthetic resin is suitable. That is, the primary filter 3 is a filter made of chemically treated polypropylene fiber, and the secondary filter 4 is a Teflon membrane filter. Of course, it is not limited to this.

There is a three-way valve 5 as a flow path changing mechanism in the middle of the delivery line after the secondary filter 4. One of the three-way valves 5 constitutes an extension of the delivery line, at the end of which a flexible tube is provided with a joint for connecting to the filling port of the tank truck, which can be connected preferably in one operation.
6,7,8 are provided. The other side of the three-way valve 5 reaches the storage tank 1 via a return line. A flow path can be switched to another IPA storage tank by a three-way valve 9 as another flow path changing mechanism in the middle of the return pipe.

The three-way valves 5 and 9 may have any mechanism, but a valve having a structure that does not generate fine particles is suitable. From this point, the diaphragm valve is preferable, but since it is not a multi-passage structure, when this valve is used, it may be used with, for example, three blocks.

The flexible tube is connected via a joint to the filling port of the tank truck 12 which is a moving tank. At this time, clean nitrogen is injected from the line and is discharged from the joint to be connected. By doing so, it is possible to prevent particulates in the air from mixing into the system during connection. If this connection is made inside a suitable box (not shown) such as a shelter, it is convenient because the connection can be made without being affected by the weather.

A three-way valve 10 is provided at the tank port of the tank truck as a tank-side channel changing mechanism for pressurization type movement, so that the channel can be switched to the tank tank and the return channel. Like the three-way valves 5 and 9, the three-way valve 10 can also be used as a flow path changing mechanism by blocking the three cylinders of the diaphragm valve. The return line is connected to the storage tank 1.

The three-way valve 10 is further connected to a plurality of hatch valves 11, 11 ',
Each hatch valve connects to a partitioned chamber in the tank truck. While opening and injecting one hatch valve, the other hatch valve is closed.

First, move the pump to transfer the IPA from the tank,
Filter the IPA with primary and secondary filters 3,4. Initially, the filter, valve, pipe, etc. are contaminated by themselves, so the IPA reaches the specified cleanliness, the three-way valve 5, the flexible tube 7, the filling port, and the three-way valve 10 on the lorry side.
From the IPA by flowing it to the return line and returning it to the tank.
Circulate. At this time, it is convenient to return the IPA, which is significantly contaminated at the beginning, from the three-way valve 9 in the middle of the return line to another general IPA storage tank 13 and store it separately to prevent the tank from being contaminated.

When a predetermined amount of IPA was circulated while being filtered, the tank tank side three-way valve 10 was closed, the filter side three-way valve 5 was operated instead, and the IPA was returned from the three-way valve 5 through the pipeline,
Return to tank 1 and circulate. During this circulation, the filling port, the three-way valve 10 on the side of the tank truck and the valve on the side of the hatch
Keep 11 conductive.

Next, the filter-side three-way valve is gradually operated to switch the flow path of the IPA to the delivery line. That is, the IPA
While stopping the circulation of IPA, the flexible tube 6,7,8, filling port, lorry side three-way valve 10, hatch side valve 11,
After passing through 11 ', IPA is injected into the partition chamber of the reel of the tank truck 12 and filled.

After the specified amount of IPA is filled, the filter side three-way valve 5
Is operated to return the IPA from the three-way valve 5 to the storage tank 1 through the return pipe, thereby circulating the IPA.

During the above IPA circulation, the hatch valve 11 that has already been used is closed and, in place, the other hatch side valve 11 'is opened. After that, operate the filter-side three-way valve 5 to
Stop the circulation of IPA and restart the other hatch side valve 1
Inject through 1'and fill.

In the present invention, the reason why the IPA is circulated to the storage tank via the filter side three-way valve 5 or the lorry side three-way valve 10 is to continuously filter the IPA. If the filtration of the filter is stopped each time during successive injection and filling, the formation of a steady flow is hindered and the fine particles are significantly mixed into the IPA, which is not preferable.

For example, when switching the hatch filling, the pump was stopped, the filtration was stopped, and restarted at the next filling. Filtration had to continue for hours.

After filling one of the lorries, when filling the other lorry, the nitrogen is discharged from the join and the outside air as described above, and is connected to the filling port of the lorry. Subsequent operations are as described above.

By doing so, it is possible to successively and successively fill the plurality of lorries with the high-purity and high-purity IPA without stopping the extraction from the storage tank.

The lorry tank is pressurized with nitrogen. The degree of pressure is appropriately determined based on the pressure resistance of the tank. By using a pressure type, it is possible to shut off from the atmosphere. Further, since IPA is saturated with nitrogen, if pressurized after being filled with the tank truck, the pressurized state can be maintained for a long period of time even without supplying nitrogen. However, it is also possible to load cylinders appropriately and replenish nitrogen.

EFFECTS OF THE INVENTION (1) Since the filtration is not stopped even during the operation of changing the filling of the lorry, a clean chemical product can always be obtained. During this time, the chemicals are returned to the storage tank, so there is no waste of product.

(2) Since it is a pressurized tank truck with clean nitrogen, it is shielded from the atmosphere, so there is no pollution during transportation.

Also, since the IPA to be filled is saturated with nitrogen, there is no drop in internal pressure during transport by truck.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the method of the present invention when IPA is filled in a lowry tank which is a pressure type transfer tank. 1 …… IPA storage tank, 2 …… Nitrogen introduction line 3,4 …… Primary and secondary filters 5,9,10 …… Three-way valve 6,7,8 …… Flexible tube 11,11 ′ …… Special lory hatch Valve 12 …… Lowry tank 13 …… General IPA tank

Claims (3)

[Claims] Claim: What is claimed is: 1. A chemical tank for storing a high-purity chemical liquid having a low cleanliness, the chemical liquid being taken out from a storage tank equipped with a nitrogen seal, and continuously filtered through a primary and secondary filter to achieve a predetermined high cleanliness. Multiple passages for purifying chemical liquid through the filter-side flow path changing mechanism, flexible tube, joint, pressure type transfer tank filling port, pressurization type transfer tank side flow path changing mechanism and hatch side valve. In a method of filling the tank with a high-purity chemical liquid having a predetermined high cleanliness by sequentially injecting it into the tank, (a) passing clean nitrogen through the flexible tube, and discharging the nitrogen to the outside from a joint at the end of the tube. While connecting the joint to the filling port of the pressurizing type transfer tank, (b) bubbling clean nitrogen into the storage tank. The chemical liquid in the tank saturated with nitrogen is continuously filtered with the filter to have a high degree of cleanliness, and is sent out through a filter side flow path changing mechanism and a flexible tube provided after the filter, c) The chemical liquid is circulated by returning the chemical liquid sent out to the tank from the pressure type movement tank side flow path changing mechanism provided in the pressure type movement tank side filling port through the return pipe to the tank, d) After that, while closing the tank type flow path changing mechanism for pressurization type movement, and instead circulating the chemical liquid by returning the chemical liquid from the filter side flow path changing mechanism to the tank via a return line, (2) The pressure type moving tank side flow path changing mechanism is connected to the tank truck and the hatch side valve of one hatch provided in the pressure type moving tank is opened. Then, by gradually operating the filter-side flow path changing mechanism to stop the circulation of the chemical liquid, the flexible tube, the pressure-type moving tank side flow path changing mechanism that has been conducted, and the hatch-side valve (F) When the predetermined amount of the chemical liquid has been injected into the one hatch, the filter-side flow passage changing mechanism is operated to return the return pipe from the flow passage mechanism. The chemical liquid is circulated by returning the chemical liquid to the storage tank via a passage, and (g) by closing the hatch side valve and opening the other hatch side valve during the circulation of the chemical liquid. Whether to switch to another hatch and then gradually operate the filter side flow path changing mechanism to stop the circulation and inject the chemical liquid into the hatch of the ground. The filling of the pressurized transfer tank by sequentially injecting the chemical liquid from multiple hatches of the pressurized transfer tank while blocking the contact with the atmosphere while continuously filtering the filter. Method. 2. The filling method according to claim 1, wherein nitrogen is discharged to the outside from the lorry filling port of the pressure type transfer tank when the flexible tube is connected. 3. The filling method according to claim 1, wherein the pressure type moving tank is a tank truck.