JP3387898B2 - How to remove moisture from gas supply system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing water in a gas supply system used for manufacturing semiconductors, chemicals, chemicals, precision machine parts and the like. More specifically, without circulating (heating) the gas supply system, the distribution pressure of the moisture removing gas is adjusted within a predetermined range, or the supply of the moisture removing gas is interrupted / continuously performed at a predetermined pitch. The present invention relates to a method for removing water in a gas supply system, which enables effective removal of water.

[0002]

2. Description of the Related Art In general, various high-purity source gases are supplied to a gas supply system such as a semiconductor manufacturing facility or a chemical manufacturing facility. In order to maintain the performance and purity of manufactured semiconductors and chemicals at a high level, it is necessary to avoid mixing impurities into the high-purity gas as much as possible.

However, when the gas supply system is opened to the atmosphere due to inspection or manufacturing interruption, air, moisture, or other impurity gas flows into the gas supply system at a stretch.

These gases are adsorbed not only on the inner surface of the pipe but also on various valves and filters which are constituent members. In particular, the filter has a large adsorption area and has a property that it is difficult to remove the adsorbed impurity molecules.

[0005]

Conventionally, in order to remove the impurity gas adsorbed inside the gas supply system, a high-purity gas is used to purge the inside of the gas supply system for a long time, or the gas is supplied by a vacuum pump. The inside of the supply system is exhausted and the gas supply system is baked from the outside. In particular, since H ₂ O molecules have a stronger adsorption force than other adsorbed molecules, baking has been said to be the most effective removal means.

Generally, as a method for confirming the removal of the impurity gas, an experiment for comparing the main components of the exhaust gas before and after baking is conducted. The maximum amount of impurity gas before baking is H ₂ O gas, and the reduction rate of water due to baking is remarkably higher than that of other gas species. In other words, water is a very troublesome gas when it is removed by exhausting at room temperature, but it can be easily removed by baking.

However, baking often adversely affects the gas supply system. For example, deterioration of material properties at high temperature and segregation on the surface due to increase of diffusion coefficient in solid, thermal decomposition and the like occur. In particular, the gas supply system itself may not accept heating due to its design. In such a case, baking cannot be performed as a method of removing water.

The present invention is intended to provide a method for efficiently removing an impurity gas without baking, and a first object of the present invention is to perform a room temperature evacuation treatment.
It is an object of the present invention to provide a gas supply system water removal method capable of effectively removing adsorbed water. A second object of the present invention is to provide a method of removing moisture in a gas supply system, which can effectively remove adsorbed moisture by keeping the flow pressure of the moisture removing gas within a specific range.

Further, a third object of the present invention is to efficiently adsorb gas even by a gas supply system having a complicated structure including a valve, a filter, a pressure regulator, a flow rate regulator, etc., by means of exhaust treatment at room temperature. Another object of the present invention is to provide a method for removing water in a gas supply system, which is capable of removing water. In addition, a fourth object of the present invention is to provide a complicated structure by interrupting / continuing the flow of the moisture removing gas at a predetermined pitch without finely controlling the flow rate of the moisture removing gas. An object of the present invention is to provide a method of removing moisture in a gas supply system, which enables efficient removal of adsorbed moisture even by a gas supply system having a configuration by exhaust treatment at room temperature.

[0010]

The present invention has been made to solve the above problems, and a method for removing water from a gas supply system according to claim 1 of the present invention removes water from the gas supply system.
Water for circulation is removed to remove water remaining inside the gas supply system.
It is a method of removing and continuously exhausting the inside of the gas supply system
In addition, the gas for removing water supplied to the inside of the gas supply system
Gas supply system that disconnects and connects the gas at a specified pitch
In the method of removing water, the gas is supplied to the inside of the gas supply system.
By turning off the gas for removing moisture,
The flow pressure of the moisture removal gas inside the gas supply system is
Minimum pressure at which the flow becomes viscous and the flow temperature of the gas for removing water
To a pressure value between the saturated vapor pressure of water and
This is what constitutes the basic configuration of the invention.

The condition for the moisture removing gas to become a viscous flow is characterized in that it is judged by the mean free path of gas molecules being smaller than the diameter of the pipe of the gas supply system. Further, an inert gas can be used as the moisture removing gas.

The gas supply system for removing the moisture is
It may be a gas supply system having a relatively simple structure including a filter and a valve, or may be a gas supply system having a relatively complicated structure including a filter, a pressure regulator, a flow rate regulator, a valve and the like.

Further, the gas supply system may be a gas supply system in which an exhaust port for the moisture removing gas is provided at the end of the gas supply system and the upstream side of the flow rate regulator.

In the method for removing moisture of the gas supply system according to the above-mentioned claim 1, the moisture removing gas is supplied by setting the supply pressure of the moisture removing gas to be supplied to the inside of the gas supply system to 100 to 4500 Torr. During the disconnection, the gas flow for water removal in the gas supply system surely becomes a viscous flow, and the gas pressure in the gas supply system becomes equal to or lower than the saturated vapor pressure of water, so that the adsorbed water molecules can be efficiently desorbed and removed. Done. Then, the desorbed water molecules are expelled to the outside by continuing supply of the next moisture removing gas, so that more efficient moisture removal can be performed.

Further, the In water removal method of the gas supply system of claim 1, the moisture removing gas from the source, without at the primary side of the gas supply system to adjust the gas flow rate, It is also possible to supply the gas to the inside of the gas supply system.
As a result, the water removal process can be performed more easily.

Further, in the method for removing water from the gas supply system according to the first aspect , the water removal gas to be supplied to the inside of the gas supply system is interrupted / interrupted at a distribution time of 0.9 to 5 seconds. It is desirable that the cutoff time is 0.3 to 175 seconds, and the cutoff and connection are repeated. As a result, the efficiency of water removal is further improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) As a result of intensive studies of the method for removing water in a gas supply system by means other than heating, the present inventors have found that water removal by adjusting the flow pressure of the gas for water removal. We came to the idea that we could improve efficiency.

When the moisture removing gas is exhausted while flowing through the gas supply system, the gas molecules flow while colliding with the inner surface of the pipe or the inner surface of the complicated filter. Water molecules are attached to the inner surface, and when the gas molecules collide with the water molecules and exchange energy, the water molecules are circulated and exhausted with the obtained energy, but the gas molecules also need to be circulated and exhausted. There is.

That is, the gas molecules that have collided and slowed down,
If it can re-collide with other gas molecules, it becomes possible to accelerate the flow due to this collision and to circulate and exhaust. In other words, in order for gas molecules and water molecules to be exhausted together, gas molecules collide with water molecules on the inner surface, and moreover, gas molecules collide with each other frequently.

In order to realize this phenomenon, the inventors of the present invention have proposed the Knudse number K (Knudse) in fluid mechanics.
I felt the need to use (n number). Knudsen number K is K = L
/ D (L: mean free path, D: representative length of object). In the present invention, the representative length D may be considered as the pipe diameter.

When the Knudsen number K is smaller than 1, that is, when the mean free path L is smaller than the pipe diameter D,
Moisture-removing gas molecules are likely to collide with each other.
Particularly, the range of 0.01 <K <1.00 is called a slip flow, and it is considered that the gas flow slips on the inner surface of the pipe. Therefore, L ≦ D is one condition targeted by the present invention.
In the present invention, a fluid satisfying L ≦ D is called a viscous flow.

On the contrary, in the range of K> 1, that is, L> D, collisions between gas molecules are reduced. Under this condition, even if the gas molecules collide with the water molecules and the water molecules can be exhausted, the probability of re-collision of the gas molecules is small, so that the gas molecules are adsorbed on the inner surface. A fluid satisfying this condition is called a molecular flow in the present invention.

Therefore, in the present invention, the viscous flow is a necessary condition. Generally, the mean free path L is L = 1 / √2πd ² n
(D: diameter of molecule, n: number density of molecule).
Since the molecular number density n is n∝P (P: gas flow pressure), it is expressed by L = k / P (k: proportional coefficient).

Although the value of the proportionality coefficient k differs depending on the gas type, there is no extreme difference. Then, considering air at 20 ° C., L = 4.98 × 10 ⁻³ / P. here,
A unit system of L (cm) and P (Torr) is used.

When P = 10 ^-3 (Torr), L = 5 (c
m) and P = 10 ^-2 (Torr), L = 0.5 (c
m) and P = 10 ⁻¹ (Torr), L = 0.05 (c
m). Now, assuming that the pipe diameter D = 0.5 (cm), the condition of L ≦ D must be satisfied in order to obtain a viscous flow, so the pressure condition of P ≧ 10 ⁻² (Torr) must be satisfied. become. Therefore, the condition for producing a viscous flow corresponds to giving a lower limit of the gas circulation pressure.

Next, the upper limit of the gas flow pressure P must be given. It can be seen that this upper limit condition is equivalent to the condition that the water adsorbed on the inner surface evaporates in the pipe. If the gas flow pressure in the pipe is equal to or lower than the saturated vapor pressure Pw of water, the water has the ability to evaporate. Therefore, if P ≦ Pw is established, the adsorbed moisture can be evaporated. Saturated vapor pressure Pw of water
The values of are shown in Table 1 for the range of 0 to 150 (° C).

[0027]

[Table 1]

At 20 ° C., Pw = 17.5 (Torr). From the above, when the moisture removing gas is air, the range of the gas circulation pressure P at which moisture can be removed is 10 ^-2 (Tor.
r) ≦ P ≦ 17.5 (Torr). Even if other gas species are used as the moisture removing gas, this pressure range does not change so much.

The gas has a molecular flow of P <10 ^-2 (To
Since it is in the range of rr), it is not necessary to make such a high vacuum to remove water, and a normal vacuum pump is sufficient. Therefore, in order to realize the viscous flow, a dry pump DP or a vacuum generator VG using a Venturi tube can be used. However, although it is easy to realize a viscous flow, it is necessary to pay attention to the condition of the saturated water vapor pressure Pw or less.

As gas for removing water, helium (H
Various gas species such as e), neon (Ne), argon (Ar), nitrogen (N ₂ ) can be used. In particular, an inert gas is extremely low in reactivity and has a property of being hardly re-adsorbed in the gas supply system, and is therefore an optimum gas for removing water.

[0031]

First Embodiment Next, a first embodiment of the method for removing water in a gas supply system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a gas supply system according to a first embodiment of the present invention. Pure argon gas (A
r) is used. The flow pressure condition capable of removing water, which is the point of the present invention, is 10 ⁻² (Torr) ≦ 20 ° C.
P ≦ 17.5 (Torr). P <10 ^-2 (Tor
In r), it becomes a molecular flow, and P> 17.5 (Torr)
Then, since the saturated steam pressure is exceeded, it becomes impossible to remove water.

The pressure regulator RG1 has a pressure of 4 (kg / cm
² G) Ar gas is supplied after reducing it to a desired pressure. The gas purifier PF removes gas impurities. The mass flow controllers MFC1, MFC2, MFC can control the flow rate of the gas flow in an arbitrary pressure range and flow rate range, and the mass flow meter MFM can measure the gas flow rate in a predetermined range.

The valves V1 to V14 are members for opening and closing the gas flow, and any member can be used as the sample S. In this configuration, a gas filter is used. API-MS is an atmospheric pressure ionized gas mass spectrometer and can specify the component gas species contained in a gas and their weight ratio.

Two types of vacuum pumps are selectively attached to the valve V9. The first is the dry pump DP, which can exhaust the gas flow pressure to 10 ^-3 (Torr),
It can be variably adjusted up to several hundred Torr depending on the flow rate from the upstream. The second is a Venturi type vacuum generator VG, and since the ultimate pressure is up to 60 (Torr), the pressure adjustment range can be exhausted up to 60 (Torr), and can be variably adjusted up to several hundred Torr by the flow rate flowing from the upstream. Therefore, the dry pump DP can cover the molecular flow region, the present invention region, and the saturated vapor pressure excess region, while the vacuum generator VG can only test the saturated vapor pressure excess region.

The construction of the vacuum generator VG is N
_{The two} gases are evacuated by circulating them while controlling the flow rate by the mass flow controller MFC, and as described above, the ultimate pressure is up to 60 (Torr).

The gas supply system piping is a bypass line B.
L, sample line SL, sample bypass line SB
L, a purge line PL, and a baking area BA. In this embodiment, the bypass line BL and the sample bypass line SBL always flow high-purity gas so as not to raise the background of the analyzer, and flow high-purity gas when confirming the background of the sample line. And is not used for the actual purging. Therefore, valves V1, V3, V4, V6 and V
11 is in a normally closed state.

During the gas flow, the baking area BA is always heated to 120 ° C., and the adsorbed water does not remain,
Water is lost from this area. Further, it is difficult for water to be adsorbed even when measuring the residual gas.

In many tests, the valves V7, V8, V12, V were first used to make the initial state of water adsorption the same.
9 is closed, V10 and V14 are opened to open the inside of the pipe, V9 is opened, air is sucked in and exhausted for 3 minutes, and then V10 is closed to return to atmospheric pressure. By maintaining this state for a certain period of time, the same amount of water is adsorbed in the pipe. During this operation, the valves V2, V13, V
6, V11 and V5 are opened, valves V1, V4 and V12 are closed, and Ar gas is flown to the sample bypass line SBL at a flow rate of 1.2 l / min to check the background.

Next, the valve V14 is closed, and the valve V
By opening 7, V9, and V10 and flowing Ar gas at a predetermined pressure, the adsorbed water in the sample S is removed by a vacuum pump for a predetermined time. After purging with Ar gas, the valves V7, V9, and V10 are closed, and the valve V
2, V5, V8, V12, V13 open, valves V6, V
11 is closed and Ar gas is passed through the sample line SL at a flow rate of about 1.2 l / min. At this time, the baking area BA is heated at 120 ° C.

That is, the water in the sample S is removed under a predetermined pressure by Ar gas purging through the purge line PL in the first stage. Then, the sample line S of the second stage
The Ar gas is exhausted while the water content is measured by the atmospheric pressure ionization mass spectrometer API-MS by the circulation of the Ar gas through L. With this, the efficiency of water removal by Ar gas purging is measured.

FIG. 2 is a detailed view of the test example. The test examples are 11 of A to H. Is a continuous purge measurement, and the remaining ~ H is measured by a combination of the above-described first stage Ar gas purge and second stage Ar gas sample line flow.

In the continuous purge measurement, purging for removing water and measurement of water content are performed simultaneously. That is,
After injection into the atmosphere, valves V7, V9, V10, V14, V
6, V11, V1, V3, V4 are closed and valves V2,
Open V13, V12, V8, and V5 and immediately start about 1.
Ar gas at a flow rate of 2 l / min is passed through the sample line SL, and the water content is measured by an atmospheric pressure ionized gas mass spectrometer API-MS.

At continuous purge measurement, room temperature (about 20 ° C.)
Ar gas is circulated at a flow rate of 1.2 SLM. The batch purge in the test example is the first-stage water removal purge performed while switching the gas pressure. For example, using a vacuum generator VG, a purge with Ar gas at a pressure of 2 (kgf · cm ² ) is performed for 5 times.
Purge with Ar gas at a pressure of 60 (Torr) for 5 seconds
(Seconds), each of them was continuously switched (60 times of switching in a total of 10 minutes).

The time in parentheses in Test Examples to H indicates the purge time for water removal, and the water content is measured after these purges. Test example is 17.5 (Torr)
This is an example of exceeding the saturated water vapor pressure of. In the test example, the saturated vapor pressure excess region and the molecular flow region are switched. Test examples A, B, C, D, E, F, and G are examples in a viscous flow region and a saturated water vapor pressure or lower region. Finally, Test Example H shows a saturated vapor pressure excess region although it is a viscous flow region. Therefore, the test examples of the present invention are A, B, C, D, E,
There are 7 examples of F and G, and the other 4 examples are comparative examples.

FIG. 3 is a comparison diagram of the residual water concentration after various purging. Tests, and H have a high rising peak immediately after the start of measurement, and show that moisture removal by continuous purging and first-stage purging is not sufficient. The apex of the test example is slightly lower than that of, but higher than those of A to G. In particular, the peaks of Test Examples A to G of the present invention are lower than those of the other Comparative Examples, demonstrating the effectiveness of the first-stage water removal purge. As can be seen from the test example and the drop Δ of the apex of C, the water concentration is reduced to 1/10. As described above, it has been proved that the moisture can be effectively removed by setting the purge pressure of the moisture removing gas in the viscous flow region and below the saturated steam pressure.

(Second Embodiment) FIG. 4 is a configuration diagram of a gas supply system according to a second embodiment of the present invention. The difference from the configuration diagram of the gas supply system according to the first embodiment shown in FIG. 1 is that a sample S for removing water includes a filter FIL, a pressure regulator RG ₂ , a mass flow controller MFC 3, and a valve. The point is that the gas supply system is close to the reality (the part surrounded by the dotted line in FIG. 3), and the exhaust is performed from two points: the upstream side of the mass flow controller MFC3 and the end of the gas supply system. .

In FIG. 4, the mass flow controller MFC3 for small flow rate has a large internal flow path resistance, and therefore exhaust is performed from two locations. However, when the internal resistance of the mass flow controller MFC ₃ is small, when the mass flow controller MFC 3 is not included, or when the dry pump DP exhaust capacity is large, the valve V9a
Needless to say, it may be a vacuum drawing from one location through.

[0048]

[Second Embodiment] In the gas supply system of FIG. 4, a pressure regulator RG ₁
Then, the Ar gas pressure is adjusted to 0.2 MPaG, and the valves V7, V8, V12, and V are first set in the same manner as in the first embodiment.
9a, V9b closed, valves V14, V15-V16, V
10 is opened to open the inside of the pipe to the atmosphere, then the valves V9a and V9b are opened to suck the atmosphere and exhaust for 3 minutes, and the valve V10 is closed to return the inside of the pipe to atmospheric pressure, By maintaining this state for a certain time, the same amount of water is adsorbed in the sample line SL.

During this operation, the valves V2, V13, V
6, V11, V5 are opened, valves V1, V4, V12 are closed, Ar gas is caused to flow through the sample bypass line SBL at a flow rate of 1.2 l / min, and its back ground is confirmed.

Next, in order to perform the first stage Ar gas purge, the valve V14 is closed and the valves V7, V9a,
By opening V9b, V10, and V15 to V19 and flowing Ar gas at a predetermined pressure, the sample line S
The adsorbed moisture in L is removed by a vacuum pump for a predetermined time.
When the Ar gas purging in the first step is completed, the valves V7 and V9 are used to measure the water content in the second step.
a, V9b, V10 are closed and valves V2, V5, V
8, V12, V13, V15 to V19 open, valve V
6. V11 is closed and Ar gas is passed through the sample line SL at a flow rate of about 1.21 / min. At this time, the baking area BA is heated at 120 ° C. And valve V5
Through, Ar gas is exhausted while measuring the water content by an atmospheric pressure ionization mass spectrometer API-MS. Thus, the efficiency of water removal by Ar gas purging is measured.

FIG. 5 shows the residual water content of the gas supply system of FIG. 4 after the Ar gas purge. The Ar gas purge was performed under the Ar gas flow rate of 19.7 sccm and the internal pressure of the dry pump DP of 14.8 Torr. Has been done.
In this case, the inner diameter of the pipe is 4.4 mm, and Ar
Since the gas pressure is 14.8 Torr, the Ar gas purge is a purge under viscous flow conditions.

In FIG. 5, the curves b, c and d are obtained by performing the Ar gas purge of the first stage for 10 minutes and 3 times.
It is the measured value of the residual water concentration after 0 minute and 60 minutes. The curve a shows the residual water concentration when continuous purging was performed under the same conditions as in Example 1, and is shown for comparison. As is clear from the comparison between the curve a and the curves b, c and d, the residual water concentration of the latter is reduced to about 1/2 of that of the former.

[0053]

Third Embodiment Next, a third embodiment of the present invention will be described. Although the configuration diagram of the gas supply system to which the third embodiment is applied is not shown, it is substantially the same as the case of FIG. That is, the only difference is that the valve V7 is configured so that it can be continuously opened and closed in a predetermined short cycle, and that the mass flow controller MFC2 is omitted.
The mass flow controller MFC2 is omitted because the Ar gas purge (Ar
This is because it is not necessary to particularly adjust the flow rate of the Ar gas to be supplied when the gas supply is interrupted / continuously performed and the purge is performed).

Also in the third embodiment, as in the first and second embodiments, the same amount of water is first adsorbed into the pipe under the same conditions. Further, Ar gas is caused to flow through the sample bypass line SBL at a flow rate of 1.2 l / min to check the background.

Next, in order to perform the first stage Ar gas purge, the dry pump DP is operated and the valves V7 and V9 are set.
a, V9b, V10, V15, V19 open, V8, V
14 and V12 are closed. Then, in the third embodiment, the valve V7 is opened / closed at a predetermined cycle, and the Ar gas supplied to the gas supply system is interrupted / interrupted, so that the Ar gas pressure in the sample line SL is controlled to several degrees. Pickup Torr (eg 60 Torr) to several Torr (eg 1 Torr)
Fluctuate over.

When the valve V7 is closed by the opening / closing operation of the valve V7, the sample line SL is exhausted to a pressure of several Torr. As a result, Ar
The gas flow enters the viscous flow region, and the pressure of the Ar gas is reduced to a pressure value lower than the saturated vapor pressure of water, which is high under the same conditions as in the first embodiment. Water is removed efficiently.

On the contrary, when the valve V7 is opened,
Within the sample line SL several Torr (eg 60To
It becomes Ar gas pressure of rr), and is outside the region of viscous flow. However, a large amount of Ar that flows in when the valve V7 is opened
Due to the gas flow, the separated water molecules in the sample line SL are efficiently pushed to the outside.

The pressure and flow rate of the Ar gas supplied to the gas supply system are appropriately selected depending on the configuration of the gas supply system, the capacity of the exhaust device (dry pump DP), the inner diameter D of the pipe line, and the like. Of course, it is usually 100-4
It is selected to be about 500 Torr.

FIG. 6 shows the residual water concentration when water is removed from the sample line SL having the same structure as in FIG. 4 according to the third embodiment, and the curves d, e, f ₁ and The curve f ₂ is the measured value in the case of the third embodiment.

That is, the curve d is 175 after evacuating by the dry pump DP and flowing Ar gas for 5 seconds.
This is the measured value of the residual water concentration when the operation of shutting off for sec is repeated for 60 minutes to perform the first stage purge. In addition, the curve e shows that after Ar gas is flown for 5 seconds,
When the operation of shutting off for 55 seconds is repeated for 60 minutes, the curve f ₁ shows that after flowing Ar gas for 5 seconds,
It shows the measured values when the operation of shutting off for 25 seconds was repeated for 60 minutes. Similarly, the curve f ₂ shows the measured value when the operation of flowing Ar gas for 5 seconds and then interrupting it for 25 seconds is repeated for 360 minutes.

On the other hand, the curve a, the curve b, and the curves C _{1 to} C ₄ in FIG. 6 are shown for comparison, respectively, and the curve a is measured when continuous purging with Ar gas is performed. It is a value and has the same contents as the curve 1 of FIG. 3 of the first embodiment and the curve a of FIG. 5 of the second embodiment.

The curve b in FIG. 6 shows that the Ar gas pressure is 2 kg.
Pressurization by f / cm ² for 10 seconds and exhaust by vacuum generator VG for 30 seconds (about 70 Torr)
It shows the measured value of (batch operation) when the operation of repeating r) is performed for 30 minutes.

Further, the curves C _{1 to} C ₄ of FIG. 6 are the same as in the case of FIG. 5 of the second embodiment, and the Ar gas flow rate is 19.7 se.
c shows the measured value of residual water concentration when the first-stage purging is performed for 30 minutes, 60 minutes, 180 minutes, and 360 minutes under the conditions of c and pressure of 14.8 Torr (that is, viscous flow purge). .

As is clear from the curve f ₂ in FIG. 6, in the case of the third embodiment, the moisture removal performance superior to that of the viscous flow purge (curve C ₄ ) in the case of the second embodiment is obtained. Obtainable.

FIG. 7 shows a valve V7 in the third embodiment.
It shows a change in water removal performance when the number of open / close switching cycles is changed. The curves in FIG. 7 are the third
The measured value of the residual water concentration in Ar gas in the example is
Also, the curve shows Ar for continuous purging for comparison.
It shows the measured value of the residual water concentration in the gas.

For example, the curve in FIG. 7 shows that when exhausted,
Ar gas purging was performed 3000 times (that is, 6 times) by saying that Ar gas was blocked for 0.3 seconds after flowing Ar gas for 0.9 seconds.
(0 minutes), and then the residual water concentration in Ar gas was continuously measured for 30 minutes.

As is clear from FIG. 7, higher water removal performance can be obtained by increasing the frequency of switching the valve V7 between open and closed.

FIG. 8 shows the third embodiment of the present invention in which the flow rate of the Ar gas is adjusted so that the purging Ar gas supplied from the primary side becomes a viscous flow, and the sample line SL. Moisture removal performance in the case where the flow rate of the purge Ar gas to be sent is not adjusted and the flow rate is initially adjusted on the Ar gas supply source side (that is, the state in which the MFC 2 in FIG. 4 is not provided). Are compared.

As is clear from the comparison between the curves in FIG. 8, the flow rate of the purge Ar gas flowing from the primary side to the sample line SL is finely adjusted during the purge so that the Ar gas flow becomes a viscous flow. Ar without adjusting the flow rate
It was confirmed that by opening and closing the valve V7 while supplying the gas pressure at about 0.2 MPaG (about 2300 Torr), almost the same water removal performance can be obtained. The actual supply pressure of Ar gas is 10
About 0 Torr to 4500 Torr (5 kg / cm ² G) is selected.

In the gas supply system according to the first and second embodiments shown in FIGS. 1 and 4, the bypass line BL and the sample bypass line SBL are provided.
Of course, the bypass line BL and the sample bypass line SBL may be omitted in the actual gas supply system water removal operation. Further, the present invention is not limited to the above-described embodiments, but includes various modifications, design changes and the like within the technical scope thereof within the scope not departing from the technical idea of the present invention.

[0071]

According to the present invention, the inside of the gas supply system is
Evacuate continuously and supply to the inside of gas supply system
Make sure that the gas for removing water is cut off and connected at a specified pitch.
In a method for removing water in a gas supply system,
While the gas for removing moisture supplied to the inside of the
Distribution of gas for moisture removal inside the gas supply system by exhaust
The pressure is the minimum pressure at which the gas flow becomes viscous and for removing water
Pressure between saturated vapor pressure of water at gas flow temperature
Since it is set to a value, it is possible to effectively remove the water adsorbed on the inner surface of the gas supply system due to the collision of gas molecules, centering on the part that cannot be baked,
It established an effective removal method other than baking. Further , according to the present invention, a viscous flow condition is given by making the mean free path of gas molecules smaller than the pipe diameter.
Therefore, the minimum pressure satisfying the viscous flow condition can be easily derived. Further, according to the present invention
If an inert gas such as Ar gas as the gas for removing moisture selection
By hitting, the gas itself is less likely to be adsorbed in the gas supply system after knocking out water molecules. In addition, according to the present invention
If, even a gas supply system is a single device such as a filter or filters and pressure regulators, mass flow controller, even complex piping system path including a control valve or the like, Moshiku
Is a piping system path that contains equipment with large flow resistance.
Even in this case, it is possible to efficiently remove water inside.

Furthermore , according to the present invention, it is possible to remove water in a more complicated gas supply system with high efficiency without adjusting the flow rate of the water removal gas supplied from the primary side with high accuracy. The water can be removed easily and easily within a short time.

Further , according to the present invention, by increasing the number of cycles of supplying and shutting off the gas for removing water , the water can be removed efficiently in a shorter time. The present invention has excellent practical utility as described above.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a gas supply system according to a first embodiment of the present invention.

FIG. 2 is a detailed view of a test example embodying various physical conditions.

FIG. 3 is a comparison diagram of residual water concentration after various purging.

FIG. 4 is a configuration diagram of a gas supply system according to a second embodiment of the present invention.

5 is a viscous flow purge by exhaust from two locations for 10 minutes, 30 minutes, and 6 respectively using the gas supply system of FIG.
It is a comparison figure of the residual water concentration when it performs for 0 minutes.

FIG. 6 is a residual water concentration in the case of a purging method in which the supply of a gas for removing water is interrupted and continued during exhaust in the same gas supply system as that in FIG. 4 and in the case of other purging methods. FIG.

FIG. 7 is a comparison diagram of residual moisture concentration when the number of interruption / continuing cycles is changed in the purging method of interrupting / continuing the supply of the moisture removal gas.

FIG. 8 is a comparison diagram of the residual moisture concentration when the supply flow rate of the moisture removal gas supplied from the primary side is adjusted and when it is not adjusted in the purging method of interrupting / continuing the supply of the moisture removal gas. Is.

[Explanation of symbols]

RG1 is pressure regulator, PF is gas purifier, MFC1 ・ M
FC2, MFC3, MFC are mass flow controllers,
MFM is a mass flow meter, V1 to V19 are valves, A
PI-MS is an atmospheric pressure ionized gas mass spectrometer, DP is a dry pump, VG is a vacuum generator, BL is a bypass line, SL is a sample line, SBL is a sample bypass line, PL is a purge line, and BA is a baking area.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Den Homoto, Akio 2-3-2, Nishimori, Nishi-ku, Osaka-shi, Osaka Prefecture Fujikin Co., Ltd. (72) Inventor, Koji Kawata 2-3-2, Nishi-ku, Osaka-shi No. Fujikin Co., Ltd. (72) Inventor Katsunori Yoneka 2-3-2 Nishimo-ku, Osaka-shi, Osaka Prefecture Fujikin Co., Ltd. (72) Akira Hirai 2-3-2 Nishi-ku, Osaka-shi, Osaka-shi In Fujikin (72) Inventor Michio Yamaji 2-3-2 Sorihori Nishi-ku, Osaka City, Osaka Prefecture (56) References JP-A-2-46726 (JP, A) JP-A-4-180567 (JP, A) JP 57-31777 (JP, A) JP 2000-120992 (JP, A) JP 2000-97398 (JP, A) JP 5-7764 (JP, A) JP 2548764 (J P, B2) Japanese Patent Publication 4-76492 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) F17D 1/00-1/20 F17D 3/14 B01D 53/26 H01L 21 / 302

Claims (4)

(57) [Claims] 1. A gas for removing moisture is circulated through a gas supply system.
Is a method of removing the water remaining inside the gas supply system.
The gas supply system is continuously exhausted and the gas
The gas for removing moisture supplied to the interior of the
Water removal method of gas supply system so that it can be disconnected and continued with
For removing water supplied to the inside of the gas supply system
While the gas is shut off, the gas supply system
The flow pressure of the moisture removal gas at the
Minimum pressure and water at the circulating temperature of the water removal gas
A method for removing water in a gas supply system, characterized in that a pressure value between the saturated steam pressure and the saturated steam pressure is set . 2. The water removal method for a gas supply system according to claim 1 , wherein the supply pressure of the water removal gas supplied to the inside of the gas supply system is set to 100 to 4500 Torr. The 3. A gas removing moisture from the source, without adjusting the gas flow rate at the primary side of the gas supply system, according to claim 1 which is adapted to supply to the interior of the gas supply system Method of removing water from gas supply system. 4. The moisture removing gas supplied to the inside of the gas supply system is repeatedly disconnected and connected at a flow time of 0.9 to 5 seconds and a flow cutoff time of 0.3 to 175 seconds. The method for removing water from a gas supply system according to claim 1 , wherein