JPH08296800A - Distributing method of ultra-high purity gas minimally stopping corrosion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize contamination in distribution of ultra high purity gas, by wet-cleaning a gas distribution network and then performing liquid drying with a specific H2 O desorbing liquid drying agent during distribution of the ultra high purity gas used for treatment of electronic material. SOLUTION: In distribution of ultra high purity gas, prior to the distribution process, cleaning liquid 25 is first supplied to a distribution network for cleaning from a pump 24 for cleaning. Then, the gas distribution network is liquid-dried with a H2 O desorbing liquid drying agent selected from a group comprising acetone dimethylacetal, 2-2 dichloropropane, 2-2 dibromopropane, mixtures thereof, and an equivalent. Next, the distribution network is purged with dry inert high purity gas comprising less than 1 ppm of any impurity, is exhausted at a pressure which is lower than 5×10<4> Pa with an operation of a vacuum pump 19, and then is exposed to atmosphere containing high purity corrosive gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to distribution of ultra-high purity gas exclusively for electronic members. In particular, this invention relates to minimizing corrosion in the distribution of ultra high purity gases.

[0002]

The use of ultra high purity chemicals, especially chemical gases, used in the processing of electronic materials is important for achieving acceptable product yield, product reproducibility and high quality in the manufacture of electronic devices. It is known to be a factor. For recent reviews, see, for example, M. Liehr and G.
W. Rubloff, J. Vac, Sci, Technol. B 12, 2727 (199
See 4). This is incorporated herein by reference.

Even though high purities have been achieved in the production and purification processes of such chemical gases, it is known that contamination can easily occur during their transport through the equipment network (also called the gas distribution network) to the point of use. Has been. This device network includes other component devices known to those of ordinary skill in the art [comp
onent], along with lengthy piping to intervene between the source (eg, gas cylinder) and point of use (eg, process reactor) in wafer fabrication and many components (eg, pressure reducers, etc.) that control pressure and flow rate. Valves, mass-flow controllers, filters, purifiers, etc.) may be included.

This problem is especially affected in the case of corrosive gases, such as halogen-containing gases, which readily react with the exposed surfaces, including the communication surfaces of the gas distribution network, by a corrosion reaction. Such corrosion reactions can not only give rise to particulate contamination, but also completely change the adsorption-desorption properties of the gas and the impurities thus modified on the surface. Ultimately, the corrosion phenomenon can lead to leakage and malfunction of moving parts. This affects the safety and effectiveness of the gas distributor.

It is known that such corrosion reaction involves the presence of water even if the amount is small.
The H ₂ O concentration of corrosive gases is currently 1 p
below pm (1 part per million) [eg Miyaza
ki et al., Bull. Chem. Soc. Japan 66, 3508 (1993);
66, 969 (1993)], the corrosion reaction often occurs by a mechanism involving water adsorbed on the contact surface of the gas distribution network.

The current goals for the purity of ultra clean electronic specialty gases transported to the point of use are 1 to 100 ppb (parts per billion) for volatile impurities and 1 particle per cubic foot [ For particle densities less than particulate] (under standard conditions) and existing metallic elements, 100 ppt (part
s per trillion) less than the metal concentration range.

The main mechanism of micro-corrosion in the above-mentioned assumed purity range is that molecules adsorbed from the surface of the substance exposed to the gas specialized for electronic members, especially those existing widely in the environment, have a particularly strong adsorption energy on the surface. This is because it is difficult to completely remove the water supplied.

Most of the gases for exclusive use of corrosive electronic members have high purity, that is, even if the H ₂ O concentration is less than 1 ppm, such adsorbed molecules, particularly H ₂ O adsorbed on the metallic surface, are present. With a tendency to react by catalytically activated chemical reactions. This catalytically activated chemical reaction promotes corrosion and the formation of volatile or solid by-products at the assumed concentrations, and at the same time the formation of solid particles.

The usual practice for purifying a gas distribution network is to purify all impurities present inside or on the contact surface of the gas distribution network by purifying an ultra-high purity inert gas (eg, less than 1 ppb). Flow of nitrogen or argon with high purity). However, this method is insufficient for strongly adsorbed molecules, such as H ₂ O molecules adsorbed on the solid surface. Improve this purging method and reduce its time by using a continuous pressure-vacuum cycle of an inert gas and by heating the surface to induce thermal desorption of strongly adsorbed species. Attempts have been made to However, these vacuum-pressure purge cycles are not effective at sites exhibiting dead space, as pumping through the fine orifices is not effective.

Another attempt has been made to perform a thermal bake at 120 ° C. while purging a metallic surface. Such methods are known to significantly reduce the time to reach background levels of purge gas. For example, ultra-high purity (impurities <1 pp) through micro leak-free gas distribution network of length of about 10 to about 200 m.
Purity of 1 ppb can be obtained in a few hours when b) nitrogen or argon is flowed at 0.1-10 standard liters per minute. However, it takes several steps to thermal desorption of of H ₂ O on electropolishing stainless steel surfaces, one last step is known to occur at temperatures of the order of 400-450 ° C.. Practical application of such temperatures is difficult. Thus, when lower baking temperatures (eg, 120 ° C. for practical reasons) are applied, metal surfaces do not completely free adsorbed moisture. Moreover, thermal baking is not practically applicable under some circumstances for safety, regulatory or material stability reasons.

For example, using a number of vacuum-pressurization cycles,
Or by increasing the flow rate of ultra high purity gas,
Other attempts have been made to improve the method of purging gas distribution networks. This can reduce the initial concentration of impurities and particles generated, but the time it takes to reach background levels is always very long, i.e. about 40 sccm at a flow rate of about 40 sccm.
It takes about 15 minutes at a flow rate of 30 sccm.

In addition, DMP (acetone dimethyl acetal), which has been reported to react with adsorbed moisture, DC
Gas phase chemical desiccants such as P (2,2-dichloropropane) or DBP (dibromopropane) (K. Tatenuma
et al., J. Vac. Sci. Technol. A11, 1719 (1993); K.
Tatenuma et al., Bunseki 223, 393 (1993)) or a chemical desiccant (publication 5-140777) as a liquid mixed with a fluorocarbon liquid is used.

Wet cleaning removes these liquid-soluble molecular species, or dilutes or mechanically rubs the liquid any molecular species or particles that may be present on the surface prior to the following wet drying. Thus, by wet cleaning the gas contact surfaces of the various components of the gas distribution network, surface impurities (molecules or particles) are removed.

Corrosion-induced surface alteration affects the adsorption energies of the surface and both the electronic component gas (ESG) and its impurities, resulting in variations in the gas composition at the point of use. . further,
In operating such a gas distribution network, it is essential to prevent the ingress of any moisture or air, or to remove the invading molecules if this occurs.

[0015]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to prevent heating for thermal desorption due to surfaces, especially deep dead space sites or practical, detrimental or regulatory conditions. It is to provide another technique for drying what is more effectively.

Further, according to the present invention, by suppressing the source of corrosion and minute contamination due to the above-mentioned volatile impurities or particulate impurities, adsorbed molecules, especially H ₂ O, can be adsorbed before introducing the gas exclusively for electronic members into the distribution network. It is also intended to provide a method of removal.

A further object of the invention is to provide a method of minimizing corrosion in the distribution of ultra high purity gases.

A further object of the present invention is to provide a method for minimizing contamination and particles caused by corrosion in the distribution of ultra high purity gases.

It is a further object of the invention to provide an apparatus for carrying out a method for minimizing corrosion in the distribution of ultra high purity gas.

[0020]

The objects are: (a) wet cleaning the gas distribution network or at least a portion thereof with a wet cleaner, and (b) cleaning the gas distribution network or at least a portion thereof. , Acetone dimethyl acetal (also called dimethoxypropane)
Liquid drying with a H ₂ O desorption liquid desiccant selected from the group consisting of (DMP), 2,2-dichloropropane (DCP), 2,2-dibromopropane (DBP), mixtures thereof and their equivalents. And a method of reducing corrosion in a gas distribution network of ultrapure gases, or portions thereof.

The above objects are also achieved by an ultrapure gas delivery system comprising means for liquid drying the gas distribution network or parts thereof with a H ₂ O desorbing liquid desiccant.

[0022]

DETAILED DESCRIPTION OF THE INVENTION The method according to the invention comprises: (a) wet cleaning the gas distribution network or at least a part thereof with a wet cleaner, and (b) the gas distribution network or at least a part thereof. , Acetone dimethyl acetal (also called dimethoxypropane) (DMP), 2,2-dichloropropane (DCP), 2,
Liquid drying with a H ₂ O desorbing liquid desiccant selected from the group consisting of 2-dibromopropane (DBP), mixtures thereof and their equivalents.

The present invention provides for the distribution of ultra high purity gases with reduced corrosion based on the improved removal of moisture adsorbed on metal surfaces and other constituent surfaces.

The method of the present invention is particularly suited to the problem of corrosion due to cylinder valves. This is because thermal desorption of molecular species adsorbed in the cylinder valve is hindered by safety and regulatory considerations.

The present invention wet-cleans at least a portion of the most corrosive gas distribution network (such as a valve), at least said portion of the gas contacting surface of the gas distribution network reacts with adsorbed moisture, and Preferably it includes liquid drying by exposure to a H ₂ O desorbing liquid desiccant which leaves substantially no particulate residue and volatile molecules deposited on the metal surface. The liquid drying of this invention preferentially removes adsorbed H ₂ O,
And it can be completed very effectively at room temperature with liquid chemistries that leave behind neither particle residues nor volatile molecules that show strong interactions with the surface. The latter is easily purged under a vacuum-pressurization cycle after the liquid drying step.

In one embodiment of the present invention, the liquid desiccant is DMP (acetone dimethyl acetal), DC
P (2,2-dichloropropane) or DBP (dibromopropane) is included. However, other H ₂ O desorption liquid desiccants well known to those skilled in the art can be used in accordance with this invention. Most preferably, pure liquids are used to combine the wet cleaning and drying properties of these molecules.

After that, it is preferable to purge residual by-products by pressurization-depressurization cycle purging, preferably using an ultra-high purity inert gas. The ultra-high purity inert gas is preferably dry and preferably has an impurity content of less than 1 ppm. Preferably thereafter, the discharging step is carried out, preferably at a pressure below 5 × 10 ⁴ Pascals. The above method is performed before exposing the surface to a gas dedicated to electronic members, in particular a corrosive gas such as HBr or ambient air.

Wet cleaning with high-purity liquids such as DI water, alcohols, acetone, etc. removes molecular species soluble in these liquids. It also removes molecular species and particles that may happen to be present on the gas contact surface prior to the wet drying by mechanical rubbing of the diluent or liquid.

This process opens the network when gas distribution networks or parts of them are inadvertently exposed to air, for example during cylinder connection or for repair or component replacement, and moisture is adsorbed to the surface. It is especially useful when The presence of adsorbed H ₂ O promotes the corrosion reaction. The deleterious effect of such accidental corrosion is due to the combination of the liquid drying step and the wet cleaning step before it (purging or decompression using a high-purity inert gas between wet cleaning and liquid drying). It can be effectively and substantially suppressed with or without the use of a pressure cycle.

In another aspect of the present invention, a similar wet cleaning and liquid drying procedure was performed immediately after purging the ESG from the components exposed to it, even though very simply. Can also be preferably applied before exposure to air. This is done to prevent unwanted corrosion that may occur due to the reaction of the residual adsorbed ESG with H ₂ O molecules that occurs after exposure to air. In fact, the reaction between the adsorbed molecules is catalytically reactivated and promotes surface reactions leading to corrosion, particles and the formation of unwanted surface molecules.

In yet another aspect of the present invention, the cycle of wet cleaning and liquid drying is repeated. This series of flow is before and after exposing the surface to ESG,
It is especially effective when the surface is exposed to air.

Among the suitable uses of the process according to the invention, in particular of the combination of steps (a) and (b), are (a)
It is intended for use before exposure to air (even for a minimum amount of time) and (b) before flushing the ESG through the gas distribution network.

The present invention is a gas distribution method exclusively for electronic components, ie, volatile reaction, which is based on the improved removal of moisture adsorbed on metal surfaces and other surfaces, with reduced or no corrosion generation. Provided is a gas distribution method exclusively for electronic members, in which by-products are reduced and particles are reduced.
The method of the present invention is particularly suitable for corrosion problems due to cylinder valves. This is because thermal desorption of the molecular species adsorbed in the cylinder valve is hindered by considering safety and regulation.

The process of the invention optionally comprises first of all said distribution networks or parts thereof, dry inert high purity, wherein the content of impurities is less than 1 ppm, more preferably the content of water vapor is less than 1 ppm. Including purging with gas. After purging and purging gas purge, the distribution network is usually emptied to below atmospheric pressure [su
b-ambient pressure]. These two first steps are repeated until a pressure of less than 5 × 10 ⁴ Pascal is reached and the content of impurities in the discharged gas is the same as that of the inert gas injected for purging. These steps (repeated as often as necessary) are known as "cycled pressure-vacuum" purges. After these two optional steps, the gas distribution network is wet washed and liquid dried as shown above. Wet cleaning is performed with high purity liquids such as DI water, alcohols, acetone or other similar cleaning agents known to those skilled in the art. The wet cleaning agent used in this step of the method according to the invention should be a high-purity cleaning agent suitable for cleaning metallic surfaces, in particular stainless steel surfaces. Here, high-purity cleaning agents are cleaning agents that, when used purely (or mixed with other cleaning agents or solvents), leave substantially no solid residue on the treated surface. , The content of solid residue is less than 1 mg per liter, preferably 10 ^-6 g per liter
Means a cleaning agent that is less than.

Wet cleaning (liquid) agent injection is shown in FIGS.
By means of suitable means as disclosed below. This injection can be performed manually by using a syringe, or automatically using a pump through a capillary tube.

The time required for this wet cleaning step is usually about
One minute or up to an hour. If the tubing and other components are new (eg, never used before), it is usually not necessary to wet clean them. A wet wash of about 1 to about 2 minutes is sufficient, even if some particles or agglutinable molecules are considered to be already attached. Distribution network piping and /
Alternatively, if other components of the network have already been used previously, it is usually recommended to wash them for about 5 to about 30 minutes, preferably about 10 minutes.

Of course, this cleaning can be applied to pipes, valves, mass flow controllers and the like. For new or existing gas distribution networks, it is advised to apply the method according to the invention each time the inner surface of the network contacts the air. For example, if the cylinder is filled with electronic component gas in the plant, it is recommended to clean / dry the valve at the end of the filling process as described herein. It is also advisable to apply the method disclosed herein, in particular steps (a) and (b), to said valves and said cylinders when the cylinders are transported in the customer's plant. A similar method should also be applied when the gas cabinet is empty and the cylinder is pulled out. Purging with an inert gas between the wet cleaning step (a) and the liquid drying step (b) is usually optional.

After the wet cleaning step (a), the gas by exposure to chemicals that react with the adsorbed molecules and leave no particulate residue and volatile molecules deposited on the metal or other surface. Followed by a step involving liquid drying of the gas contacting surface of the distribution network. This wet-drying process aims to prevent the catalytic reaction of the decomposition of the gas for exclusive use of electronic components flowing through the distribution network by water. Liquid drying according to the invention preferably removes adsorbed H ₂ O and leaves no particulate or volatile residues (liquid / vapor), but is chemically active towards adsorbed moisture. It can be effectively completed at room temperature with liquid chemicals. (Free of particulate residue means that the liquid usually contains less than 1 mg, preferably less than 10 ⁻⁶ g of particles per liter). These liquid chemicals are easily purged under vacuum-pressure cycles after liquid drying.

The time required for this liquid drying is preferably about
1 to about 20 minutes. New distribution network equipment or piping with internal roughness of 5 × 10 ^-6 m
When it is less than (Ra <5 × 10 ⁻⁶ m), it is usually about 1
Minutes to about 2 minutes is sufficient. However, if the equipment, piping or network is not new and / or the surface roughness Ra is greater than 5 × 10 ⁻⁶ m, it is usually recommended to treat with a desiccant for about 10 minutes or more.

According to the present invention, the H ₂ O desorption liquid desiccant is DMP (acetone dimethyl acetal), CDP.
(2,2-dichloropropane) or DBP (2,2-dibromopropane), mixtures thereof and their equivalents. Here, the equivalent is a liquid capable of reacting with adsorbed moisture and substantially leaving neither a particulate residue nor a volatile molecule attached to a metal or other surface, It is defined as a liquid whose function is to prevent the catalytic reaction of the decomposition of the gas for exclusive use of electronic components flowing through the distribution network by water. Most preferably, pure liquids are used to combine the wet cleaning and chemical drying properties of these molecules.

According to one aspect of the present invention, the above-mentioned three kinds of drying liquids (DMP, DCP or DBP) are extremely effective when used after the wet cleaning step disclosed above, and other H ₂ O. It has been unexpectedly found that it is not possible to accurately predict whether other molecules of desorbed liquid desiccants could be used as successfully as well.
However, it is within the skill of one in the art to try to determine if other H ₂ O desorption solutions are suitable.

Usually after that, residual by-products are purged, preferably by a pressure-vacuum cycle purge with an ultrapure inert gas, preferably having an impurity content of less than 1 ppm.

In a particularly preferred embodiment of this invention,
Purge the gas distribution network with an inert gas such as nitrogen, argon, helium or an active gas such as hydrogen after the wet cleaning and liquid drying steps are completed and before the ESG is transported. To do. The purging time varies from about 1 minute to about 10 minutes, and is preferably
2 to 5 minutes. The gas used for this purging should, of course, be very pure, ie less than 100 ppb of volatile impurities and less than 1 particle per liter at standard conditions of temperature and pressure. (This purging with the above gases is usually alternating with depressurization). The ESG is then introduced into the gas distribution network. For purposes of this invention, ESG means a corrosive gas or a gas dedicated to electronic components that has or is suspected of being corrosive. Of course, a gas distribution network, or part thereof, treated essentially as described above, is used to flow either corrosive gases or other gases (such as N ₂ ). The method essentially involves various processing steps to reduce corrosion, with or without further flow of corrosive gas through the gas distribution network.

In another aspect of the invention, I.S. C.
After flowing the ESG for a manufacturing process such as manufacturing,
The wet-cleaning and liquid-drying steps (a) and (b) of the present invention are further carried out immediately after purging the distribution network with ESG, but simply before exposing the network to air. This reduces the occurrence of undesired chemical reactions between residual adsorbed ESG and H ₂ O molecules that occur after air exposure. In fact, the reaction between such adsorbed molecules is catalytically reactivated and promotes surface reactions leading to corrosion.

In yet another embodiment of this invention, 2
More than one cycle of wet washing (eg first using DI water (less volatile) etc., then acetone or alcohol (more volatile) etc.) and at least one cycle of wet drying. This sequence of flows is particularly effective both before and after exposing the gas contacting surface of the gas distribution network to ESG, especially when the surface is exposed to air.

Among the many suitable uses of the method of the invention are (a) exposure to air (even for a minimum time) and (b) ES through a gas distribution system or part thereof.
Before shedding G, she is aiming to use it before.

The above process can be applied to the entire gas distribution network. However, the most critical part is the part that contains dead space as found in valve structures or other components such as mass flow controllers, pressure regulators and the like. Therefore, the present invention is particularly directed to such components in gas distribution networks.

The gas distribution network capable of carrying out the wet cleaning and / or liquid drying process of the present invention is somewhat complicated due to the dead space contained in the valve structure. Accordingly, the present invention is also directed to a gas distribution network with minimal dead space and in which the method of the present invention can be practiced.

The apparatus for carrying out the method of the invention is
Means for wet cleaning the gas distribution network and means for liquid drying the gas distribution network with H ₂ O desorbent.

According to one aspect of the apparatus of the present invention, the wet cleaning and / or liquid desiccant can be manually introduced into the gas distribution network using the syringe type introduction system shown in FIGS. it can.

In a preferred embodiment of the apparatus of the present invention, the wet cleaning and / or the circulation of the liquid desiccant is achieved by using a capillary tube, and as shown in FIG. 1, it is equipped with a circulation pump as a preferable operation method. .
The apparatus of Figure 1 provides a mechanically activated liquid circulation system designed to reach deep dead spaces present within the components of a gas distribution network implementing the method of the present invention. The system is based on a pump that provides liquid flow, a capillary inlet-outlet line that provides fine dead space, and an assembly that allows minimal air exposure when handling and connecting and disconnecting clean liquid. The device of FIG. 1 is described further below.

The cylinder valve head shown in FIG. 1 includes a cylinder valve 1, a diaphragm 2, a spring 3 and a spindle.
4, polymer sealant such as diflon [Diflon], Teflon [Teflon] 5, cylinder valve port 6, gas flow from cylinder (eg HBr) 7, cylinder valve outlet
8, polymer packing 9 and fittings and connectors 10
It is equipped with.

The cylinder valve head assembly is in fluid communication with the entire length of the capillary tube 11 and the first end of the "T" type male connector 12. Wet cleaning and /
Alternatively, the first end of the three-way diaphragm valve for liquid desiccant inlet 20 is in fluid communication with the second end of the "T" type male connector 12. We used ceramic cement as a vacuum tight, non-reactive and non-gas releasing metal-metal binder.

The liquid pump 24 is a second three-way diaphragm valve for the wet cleaning and / or liquid cleaning agent inlet 20.
It is in fluid communication with the end. The liquid pump 24 has a
There is fluid communication with the m filter 26 and the wet cleaner or liquid desiccant 25.

Wet cleaning and / or liquid desiccant inlet
The third end of the three-way diaphragm valve for 20 has fluid communication with the diaphragm valve 21, which is 0.1 μm further.
The m filter 22 and the dry gas inlet 23 communicate with each other.
The dry gas inlet 23 is a purge gas (usually an inert or reactive gas used between the cleaning step and the drying step).
Used to introduce.

The third end of the "T" type male connector 12 has a three-way diaphragm valve 14 for discharging with a non-lubricated vacuum pump 19, a three-way diaphragm valve 15 for monitoring moisture with a hygrometer 18, and a The diaphragm valve 16 and the exhaust line 17 for wet cleaning and / or liquid drying, which are connected to a recovery means (not shown) for recovering the product, are sequentially in fluid communication.

The operation of the apparatus of FIG. 1 is carried out as follows: 1. Close the cylinder valve; 2. Open valve 16 and close valves 14, 15, 20 and 21; Insert the capillary tube; 4. Connect the device with the connector 10 to the cylinder valve outlet 8
5. Open valve 20 to activate pump 24 (automatic) or syringe (manual), and wash solution through the capillary tube.
25 to the cylinder valve; 6. Monitor the color or pH of the discharged liquid; 7. Continue cleaning until the discharged liquid is colorless or pH 7; 8. After cleaning, in a container filled with dry chemicals Replace and introduce dry chemical into cylinder valve; 9. After dry chemical introduced, stop pump 24 and valve 2
Close 0; 10. Open valve 21 to introduce dry gas and purge the line until no more liquid is observed in the exhaust line; 11. Time required for complete dry-down If very short, close valves 16 and 21, open valve 14 and empty cylinder valve by vacuum pump 19; 12. Close valve 14 and open valves 16 and 21; Purge the cylinder valve with dry gas; 13. Open valve 15, close valve 16 and monitor the moisture concentration in the dry gas with a hygrometer; 14. Cylinder valve until moisture concentration less than 1ppm (<1ppm) Continue to dry completely; 15. Disconnect the connector 10 of the device, introduce a small amount of desiccant into the cylinder valve, and install a blind cap on the cylinder valve.

Another aspect of the invention, which has the advantage of easier connection and autonomous operation, is disclosed in FIG.
Here, the valve and the connector portion exposed to air under the operating condition of the conventional gas cylinder are exhausted by using a non-lubricating pump. The liquid detergent and the liquid desiccant are introduced as jets driven by the difference between the pressure surrounding the liquid (atmospheric pressure) and that present in the valve and its connector part, respectively.

The operation of the apparatus shown in FIG. 2 is carried out as follows: (I) Wet cleaning process 1. Cylinder valve 101 is closed.

2. Fill the high-pressure container 114 with the cleaning liquid and close the cap.

3. The high pressure (1.
1-10 × 10 ⁵ Pa) Dry gas is introduced and the pressure is checked by gauge 116.

4. Syringe 121 contains dry chemical 122.

5. Valves 117, 118, 124, 125, 12
Close 6, 132 and 133.

6. Connector 110 connects device to cylinder valve outlet 108.

7. The pump 135 is operated, the valves 133 and 125 are opened, and the cylinder valve is exhausted.

8. After exhausting the cylinder valve until the vacuum gauge shows less than 5 × 10 ⁴ Pa, the valve 125 is closed.

9. Open the valve 117 and introduce a compressed (1.1-10 × 10 ⁵ Pa) cleaning liquid into the cylinder valve.

10. After introducing the cleaning liquid, the valve 117 is closed.

11. Hold the wash solution for 0.01-15 minutes.

12. Open valve 125, drain spent cleaning liquid via line 127 and evacuate cylinder valve (pump still running).

13. After exhausting the cylinder valve until the vacuum gauge shows less than 5 × 10 ⁴ Pa, the valve 125 is closed.

14. (The used cleaning solution is colorless or has a pH of 7
Valve exhaust-cleaning liquid filling cycle (Step 9
Repeat -13) once or more.

15. After cleaning, the valve 117 is closed and the supply of cleaning liquid is stopped.

16. Evacuate the cylinder valve via line 127.

17. After exhausting the valves, valves 125 and 1
Close 33.

(II) Wet Chemical Drying Process 18. After wet cleaning, the valves 132 and 126 are opened and the cylinder valve is evacuated.

19. After exhausting the cylinder valve, the valve 126
To close.

20. Open the valve 118 and introduce dry gas of 1.1-10 × 10 ⁵ Pa into the cylinder valve.

21. After introducing the dry gas, the valve 118 is closed.

22. Open the valve 126 and set the vacuum gauge to 5
Exhaust the cylinder valve until it shows less than × 10 ⁴ Pa.

23. Exhaust-dry gas fill cycle (step 19
Repeat -22) 1-10 times to remove the cleaning liquid remaining in the cylinder valve.

24. After the above repeating cycle, valve 1
18 is closed and valve 126 is opened to exhaust the cylinder valve.

25. After exhausting the cylinder valve, the valve 126
To close.

26. Open valve 124 and introduce dry chemistry 122 into the cylinder valve through a fine tube.

27. Dry chemical agent 122 is put in the cylinder valve.
Hold for 0.01-10 minutes.

28. Open the valve 126 and set the vacuum gauge to 5
Exhaust the cylinder valve until it shows less than × 10 ⁴ Pa.

29. Close valve 126.

30. Exhaust-dry chemical fill cycle (process
Repeat steps 25-28 several times (2-20) to remove water from the cylinder valve.

31. After the above repeated cycle, valve 1
24 is closed and valve 126 is opened to exhaust the cylinder valve.

32. After exhausting the cylinder valve, the valve 126
To close.

33. The valve 118 is opened, and 1.1-10 × 10 ⁵ Pa of dry gas is introduced into the cylinder valve.

34. After introducing the dry gas, the valve 118 is closed.

35. Open the valve 126 and set the vacuum gauge to 5
Exhaust the cylinder valve until it shows less than × 10 ⁴ Pa.

36. Exhaust-dry gas fill cycle (step 32
-35) is repeated more than 10 times to remove water and hydrocarbons in the cylinder valve.

37. Moisture concentration less than 1 ppm (<1 ppm)
And the above cycle is repeated until the carbohydrate concentration is less than 100 ppm (<100 ppm).

38. After the above impurities reach that level,
While blowing dry gas from the outlet of the connector 110 equipped with the opening valve 118, the connector 110 of the apparatus is cut off, and immediately thereafter, the blind cap is attached.

As described above, the present invention provides a method for reducing corrosion and corrosion in a gas distribution network of ultra-high purity gas with minimized particles. This method, in addition to the volatile substances and other impurities present in the network, in order to substantially remove the H ₂ O adsorbed to the gas contact surface of the gas distribution system, the use of wet cleaning agent, drying agent And liquid drying the distribution network at. Removal of adsorbed H ₂ O reduces undesired reactions with dedicated gases that result in the generation of particles, contaminants and corrosion.

Thereafter, the distribution network is preferably purged with a dry gas having a purity of better than 1 ppm for each of the impurities and then evacuated, followed by either ultra-high purity corrosive gas or air, or its Expose to both. Thus, the present invention provides an improved method of delivering ultra high purity gas to the point of use with minimal corrosion.

[0099]

The following examples are provided to further illustrate the present invention and its advantages. These are intended to be illustrative only and not in any way limiting.

Example 1 As an example of this invention, HBr recovered from a gas cylinder through a cylinder valve was analyzed.

Under normal operating conditions using a vacuum cycle purge, a very large particle count rate was observed when the gas was flowed through the cylinder valve port and a short metal pipe for sampling, as shown in FIG. To be done. Also, the metallic surfaces of both the valve ports and the piping are visible due to the formation of green or reddish surface products. Chemical analysis revealed the formation of iron bromide hydrate on the surface. The above behavior is believed to be related to the presence of water adsorbed on the metal parts exposed to air. The adsorbed water reacts with HBr to produce the above-mentioned corrosion and impurities in the form of particles.

As shown in FIG. 3, the degree of corrosion can be improved, for example, by using a higher number of vacuum-pressurization cycles or by improving the line purge procedure by increasing the flow rate or flow time of HBr. And the concentration of particles produced is reduced.

In contrast, at least the interior of the valve and its outlet portion are wet washed with a wet cleaner such as DI water, or acetone or IPA, and then liquid dried with a H ₂ O desorption liquid desiccant and then liquid dried. Using the method of the present invention, which includes a subsequent vacuum purge of residual gas, as shown in the graphs of FIGS. 4 and 5, immediately after valve opening, the reduced pollutant transport and the reduced particle count of the gas are reduced. In addition, it is possible to eliminate surface corrosion essentially completely.

Example 2 The degree of corrosion of cylinder valves can be accurately measured by applying a leaching method with DI water followed by chemical analysis of the rinse solution (Hattori et al., Jp.
n. J. Appl. Phys. 33, 2100 (1994), which is incorporated herein by reference). The metal concentration in a given volume of leach solution is proportional to the extent of corrosion, ie the volume of soluble corrosion products.

By this method, considerable corrosion will occur if the valve is used normally, that is, if the cylinder valve is exposed to the ambient atmosphere after a vacuum cycle purge of the cylinder connection. Was found. However, when the method of the present invention is applied, that is, by performing pre-wet cleaning with DI water or IPA, and then liquid drying using a H ₂ O desorbing liquid desiccant, corrosion upon exposure to air is essential. However, it could not be detected as shown in the graph of FIG.

Example 3 Dichlorosilane (DCS) is another commonly used corrosive gas. As revealed by metal leaching tests (FIG. 6), the valves exposed to air and then DCS flushed after vacuum cycle purging had noticeably colored valves.

Symmetrically, when this invention is used, ie, pre-wet washed with DI water or IPA, followed by liquid drying with a H ₂ O-removing liquid desiccant, followed by DCS flush for the same time. Corrosion was essentially undetectable (Fig. 6).

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. It should also be understood that this invention is not unreasonably limited to the embodiments shown herein.

[Brief description of drawings]

FIG. 1 shows an embodiment of an apparatus for carrying out the method of the invention.

FIG. 2 shows another embodiment of an apparatus for carrying out the method of the invention.

FIG. 3 is a graph showing particles emitted from a gas cylinder through a cylinder valve.

FIG. 4 is a graph showing particles emitted from a gas cylinder through a cylinder valve that has been liquid dried according to the present invention.

FIG. 5: HBr before and after liquid drying according to the present invention
The graph which compares and shows the total metal leached from the cylinder valve to DI water.

FIG. 6: DCS before and after performing liquid drying according to the present invention
The figure which compares and shows the total metal leached in DI water which rinsed the cylinder valve.

[Explanation of symbols]

1, 101 ... Cylinder valve, 2, 102 ... Diaphragm,
3, 103 ... Spring, 4, 104 ... Spindle, 5, 10
5 ... Polymer sealant, 6, 106 ... Cylinder valve port, 7, 107 ... Gas flow from cylinder, 8, 108 ... Cylinder valve outlet, 9, 109 ... Polymer packing,
10, 110… Fittings and connectors, 11… Capillary tubes, 12
… T-type male connector, 14, 15, 20… Three-way diaphragm valve, 16,21… Diaphragm valve, 17… Exhaust line, 18
… Hygrometer, 19, 135… Non-lubricated pump, 22, 26… 0.1μ
m filter, 23 ... Dry gas inlet, 24 ... Liquid pump, 25
... Wet cleaning liquid or liquid desiccant, 111 ... Male cross connector, 112, 119 ... Dry gas (1.1-10 × 10 ⁵ Pa) inlet, 113 ... Check valve, 114 ... High pressure container, 115 ... Cleaning liquid, 116 ... Pressure gauge, 117, 124, 126, 132… Air two-way valve, 118, 125, 133… Air three-way valve, 12
0 ... 0.1 μm filter, 121 ... Syringe, 122 ... Dry chemical, 123 ... Fine tube (inner diameter: 0.01-1 mm),
127 ... Used cleaning liquid discharge line, 128 ... Liquid trap, 129 ... Used cleaning liquid, 130 ... Used cleaning liquid disposal valve, 131 ... Vacuum assisted N ₂ cycle purge line, 134
... vacuum gauge

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location // B01J 4/02 B01J 4/02 A (72) Inventor Toshiyuki Tsukamoto Minami Kashidacho, Ushiku City, Ibaraki Prefecture 2-7-19, Sharm Yu No. 101 (72) Inventor Kohei Tarutani 14-31 Onogawa, Tsukuba City, Ibaraki Prefecture (72) Inventor Jean-Marie Fleet 1-28-7 Shinkawa, Chuo-ku, Tokyo Sumida River・ Side Tower 1401

Claims (18)

[Claims] 1. A method for reducing corrosion in a gas distribution network of ultra-high purity gas or a portion of the distribution network, comprising: (a) wet cleaning the gas distribution network or at least a portion thereof with a wet cleaner. (B) the gas distribution network or at least a portion thereof, acetone dimethyl acetal (DMP),
Liquid drying with a H ₂ O desorption liquid desiccant selected from the group consisting of 2,2-dichloropropane (DCP), 2,2-dibromopropane (DBP), mixtures thereof and their equivalents; ) Purging the distribution network or at least a part thereof with a dry high-purity gas having an impurity content of less than 1 ppm, (d) reducing the distribution network or at least a part thereof to less than 5 × 10 ⁴ Pa Evacuation at a pressure of (e), and (e) exposing the distribution network or at least a portion thereof to an atmosphere containing ultra-high purity corrosive gas or air. 2. The method of claim 1, wherein the wet cleaning step is carried out for about 1 minute to about 1 hour. 3. The wet cleaning step is carried out for about 1 minute to about 2 minutes using an ultrapure gas distribution network essentially comprising previously unused components or parts thereof. Item 2. The method according to Item 2. 4. The wet cleaning step is carried out using an ultrapure gas distribution network essentially comprising components that have been used at least once previously or parts thereof.
3. The method according to claim 2, which is carried out for 1 to 30 minutes. 5. The liquid drying in step (b) is performed for about 1 minute to 20 minutes.
The method according to claim 1, which is performed for a minute. 6. Ultra-high purity gas essentially comprising previously unused components or parts thereof, the roughness Ra of their internal surfaces being less than 5 × 10 ⁻⁶ m. 6. The method of claim 5, wherein said liquid drying step is carried out for about 1 to 2 minutes using a distribution network of 7. A liquid network of ultra-high purity gas essentially comprising components or parts thereof that have been used at least once before, and said liquid drying step comprising about 10 times.
The method according to claim 5, which is carried out for not less than a minute. 8. The liquid-drying step is carried out by using a distribution network of an ultra-high purity gas, which essentially comprises a constituent device having an internal surface roughness Ra of more than 5 × 10 ⁻⁶ m or a part thereof. The method according to claim 5, which is performed for 10 minutes or more. 9. The method of claim 1, wherein the wet cleaner is a liquid having a particulate matter content of less than 1 mg per liter. 10. The method of claim 1, wherein the wet detergent is a liquid having a particulate matter content of less than 10 ⁻⁶ g per liter. 11. The method of claim 1, wherein the wet cleaner is selected from the group comprising distilled water, isopropyl alcohol, acetone and mixtures thereof. 12. The method of claim 1, further comprising repeating steps (a) and (b) before step (c). 13. The method according to claim 1, comprising purging the gas distribution network or parts thereof with an inert gas or a reactive gas between steps (d) and (e). 14. The inert gas or reactive gas is
14. The method of claim 13 selected from the group comprising nitrogen, argon, helium and hydrogen. 15. The inert gas or reactive gas is
15. A process according to any one of claims 13 or 14 containing less than 100 ppb of volatile impurities and less than 1 particle per liter under standard conditions of temperature and pressure. 16. The method of claim 1, wherein the gas distribution network comprises at least one cylinder valve. 17. The method of claim 16 wherein said cylinder valve is subjected to at least steps (a) and (b) before and after contacting its interior surface with ambient air. 18. In step (e), prior to exposing the gas distribution network or part thereof to ambient air,
The method of claim 1 further comprising purging the gas distribution network or portions thereof with a high purity inert gas.