JP2013171757A - Inert gas purging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a consumption of an inert gas without making worse an atmosphere in a work space after substitution of the inert gas when purging the work space with the inert gas by free flowing of the inert gas.SOLUTION: A drying chamber 26 includes main and sub supply pipes 28, 30 which supply a nitrogen gas, a main discharge pipe 32 which discharges an internal gas, and a sub discharge pipe 34 having a smaller diameter than the main discharge pipe 32 and discharging the internal gas. When the inside of the drying chamber 26 is purged with the nitrogen gas, a supply amount of the nitrogen gas and a discharge amount from the main discharge pipe 32 are adjusted so that the pressure in the drying chamber 26 is higher than atmospheric pressure with the sub discharge pipe 34 closed. After the gas substitution process, the supply amount of the nitrogen gas and a discharge amount from the sub discharge pipe 34 are adjusted so that the pressure in the drying chamber 26 is higher than the atmospheric pressure with the main discharge pipe 32 closed, and the flow rate is smaller than in the gas substitution process.

Description

  The present invention relates to an inert gas purge method.

  When manufacturing an organic electroluminescence (EL) product, an organic photo vortex (PV) product, etc., the working space substituted by inert gas, such as nitrogen gas, may be needed. As a method of replacing the inside of the work space with an inert gas, a method of supplying the inert gas into the work space after forcibly exhausting the work space to bring it into a vacuum state, or a method of supplying an inert gas into the work space. A system is known in which positive pressure gas in the working space is exhausted from the pressurizing valve while supplying and the oxygen concentration is gradually lowered (Patent Document 1). Of these, the former method requires high pressure resistance and sealability for the structure forming the work space, and thus the cost is increased accordingly. On the other hand, the latter method does not require high pressure resistance and sealability.

JP2011-65967A (paragraph 0046)

  However, the latter method has a problem that the amount of the inert gas used becomes large because the inert gas is poured. In view of this problem, it is conceivable that the flow rate is set large until the inside of the work space is replaced with the inert gas, and then the flow rate is set small when the state replaced with the inert gas is maintained. However, in that case, there were the following problems. That is, in order to increase the flow rate of the inert gas, it is necessary to make the exhaust pipe have a large diameter corresponding to the flow rate, but when the flow rate of the inert gas is decreased, the atmosphere in the work space is reduced. It sometimes worsened. The cause is not clear, but it is thought that backflow from the discharge pipe occurs, or gas that is not sufficiently substituted with nitrogen gas remains in the puddle in the discharge pipe and diffuses.

  The present invention has been made to solve such problems, and in purging the work space with the inert gas by flowing the inert gas, the work space in the work space after being replaced with the inert gas is provided. The main purpose is to suppress the amount of inert gas used without deteriorating the atmosphere.

The inert gas purging method of the present invention comprises:
Working space,
A supply pipe for supplying an inert gas to the working space;
A main discharge pipe for discharging the internal gas of the working space;
A sub-discharge pipe that discharges internal gas in the working space with a smaller diameter than the main discharge pipe;
An inert gas purge method for filling the work space of the workpiece processing apparatus with an inert gas,
(A) Gas replacement step of adjusting the supply amount from the supply pipe and the discharge amount from the main discharge pipe so that the internal pressure of the work space becomes higher than the atmospheric pressure with the sub-discharge pipe closed. When,
(B) After the gas replacement step, with the main discharge pipe closed, the internal pressure of the work space is higher than atmospheric pressure, and the flow rate is smaller than that in the gas replacement step. An atmosphere maintaining step for adjusting the supply amount from the supply pipe and the discharge amount from the sub-discharge pipe;
Is included.

  In this inert gas purge method, the flow rate of the inert gas in the atmosphere maintaining step is made smaller than the flow rate of the inert gas in the gas replacement step. For this reason, the usage-amount of an inert gas is suppressed compared with the case where the flow volume of the inert gas in an atmosphere maintenance process is made the same as the flow volume of the inert gas in a gas replacement process. Further, a main discharge pipe having a large diameter is used in a gas replacement process where the flow rate of the inert gas is relatively large, and a sub-discharge pipe having a small diameter is used in the atmosphere maintaining process where the flow rate of the inert gas is relatively small. Here, if the main discharge pipe having a large diameter is used in the atmosphere maintaining step, the atmosphere in the work space may be deteriorated because the flow rate is small. The reason seems to be that a backflow from the main discharge pipe occurs, or a gas that is not sufficiently substituted with the inert gas remains in the wells in the main discharge pipe and diffuses. However, in the present invention, the atmosphere in the work space is not deteriorated because the sub-discharge pipe having a diameter smaller than that of the main discharge pipe is used in the atmosphere maintaining step.

  In the inert gas purging method of the present invention, in the gas replacement step and the atmosphere maintenance step, the internal pressure of the working space only needs to be higher than atmospheric pressure, and for example, it becomes a predetermined fixed value (> atmospheric pressure). Alternatively, it may be raised or lowered stepwise with time in a range higher than atmospheric pressure.

  In the inert gas purging method of the present invention, in the gas replacement step and the atmosphere maintaining step, the internal pressure of the work space may be higher by 100 to 1000 Pa than the atmospheric pressure. In this way, the working space can be replaced with an inert gas in a relatively short time, and the atmosphere after replacement can be easily maintained. If the pressure is less than 100 Pa, the work space may not be sufficiently replaced with an inert gas, or even if it can be replaced with an inert gas, it may take a long time or it may be difficult to maintain the atmosphere after the replacement with the inert gas. is there. On the other hand, if it exceeds 1000 Pa, it is necessary to increase the pressure resistance and sealability of the work space, which increases the cost. In addition, it is more preferable to make the internal pressure of the working space 500 to 1000 Pa higher than the atmospheric pressure.

  In the inert gas purging method of the present invention, the auxiliary exhaust pipe may be branched from the main exhaust pipe. The main discharge pipe and the sub discharge pipe may be individually connected to the work space, but in this case, when the main discharge pipe is closed, the atmosphere from the work space to the closed position of the main discharge pipe is accumulated. May be difficult to maintain. On the other hand, if the sub-discharge pipe branches off from the main discharge pipe, the sub-discharge pipe is connected between the work space and the closed position of the main discharge pipe, so that such an accumulation is unlikely to occur.

  In the inert gas purging method of the present invention, the supply pipe may be provided above the main discharge pipe and the sub discharge pipe. In this way, since the inert gas flows from the top to the bottom in the work space, even if there is dust in the work space, the dust is suppressed from above without rising. As a result, the work space can be kept clean.

  In the inert gas purging method of the present invention, the working space may be a space for manufacturing or processing a substrate having an organic thin film. For example, when processing a substrate provided with an organic thin film, such as an organic EL product or an organic PV product, if oxygen or water is present, they may cause a chemical reaction with the organic thin film and deteriorate characteristics. For this reason, it is highly necessary to carry out in an inert gas atmosphere.

  In the inert gas purge method of the present invention, the inert gas is not particularly limited, and examples thereof include nitrogen gas and argon gas.

1 is a schematic plan view of a work processing apparatus 10. 3 is a schematic side view of a drying chamber 26 that constitutes the work processing apparatus 10. FIG. 3 is a cross-sectional view illustrating the periphery of a lower portion of a drying chamber 26. It is a graph which shows the relationship between the elapsed time in a gas substitution process, and a dew point. It is a graph which shows the relationship between the elapsed time and oxygen concentration in a gas substitution process. It is a graph which shows the relationship between the elapsed time and oxygen concentration in a gas substitution process.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view of a workpiece processing apparatus 10 that processes a workpiece (here, an organic thin film substrate), and FIG. 2 is a schematic side view of a drying chamber 26 that constitutes the workpiece processing apparatus 10.

  The workpiece processing apparatus 10 includes a preparation chamber 14 in which a substrate rack 12 having a plurality of shelves is arranged, a transfer chamber 22 in which a substrate transfer unit 20 is arranged adjacent to the preparation chamber 14, and adjacent to the transfer chamber 22. And a drying chamber 26 in which a substrate rack 24 is disposed. The preparation chamber 14, the transfer chamber 22, and the drying chamber 26 are sealed spaces, but pressure resistance and sealing properties are not so much considered. The preparation chamber 14 includes an outer shutter 16 that opens and closes an entrance provided on a wall facing the outside, and an inner shutter 18 that opens and closes an entrance provided on a wall facing the transfer chamber 22. The drying chamber 26 is a room that functions as a hot air drying furnace, and is provided with a shutter 27 at an entrance provided on a wall facing the transfer chamber 22. The substrate transfer unit 20 in the transfer chamber 22 has a hand member 20a having a U shape in plan view. The hand member 20a can be moved in a horizontal direction or a vertical direction by an arm (not shown). In the substrate transport unit 20, the organic thin film substrate is removed from the shelf of the substrate rack 12 in the preparation chamber 14 by the hand member 20 a with the outer shutter 16 of the preparation chamber 14 closed and the inner shutter 18 of the preparation chamber 14 opened. They are pulled out to the transfer chamber 22 or stored in the shelf of the substrate rack 12 from the transfer chamber 22 (refer to the two-dot chain line in FIG. 1). Further, with the outer shutter 16 of the preparation chamber 14 closed and the shutter 27 of the drying chamber 26 opened, the organic thin film substrate is stored in the shelf of the substrate rack 24 in the drying chamber 26 from the transfer chamber 22 by the hand member 20a. (See the alternate long and short dash line in FIG. 1), and conversely, the substrate rack 24 is pulled out to the transfer chamber 22. Such an operation is performed after purging each of the chambers 14, 22, and 26 with nitrogen.

  Next, the case where each internal space (working space) of the preparation chamber 14, the transfer chamber 22, and the drying chamber 26 is purged with nitrogen gas that is an inert gas will be described. Here, a case where the internal space of the drying chamber 26 is purged with nitrogen gas will be described as an example. The preparation chamber 14 and the transfer chamber 22 are similarly purged with nitrogen gas.

  As shown in FIG. 2, a main supply pipe 28 for supplying nitrogen gas is attached to the upper portion of the drying chamber 26. The main supply pipe 28 is connected to a nitrogen cylinder. The main supply pipe 28 is provided with a sub supply pipe 30 in parallel on the way from the nitrogen cylinder to the drying chamber 26. A first supply opening / closing valve 28a and a first flow rate adjusting valve 28b are arranged in series in a portion of the main supply pipe 28 that is in parallel with the sub supply pipe 30. In addition, a second supply opening / closing valve 30a and a second flow rate adjusting valve 30b are arranged in series in the sub supply pipe 30.

  On the other hand, a main discharge pipe 32 for exhausting internal gas is attached to the lower part of the drying chamber 26. The main discharge pipe 32 opens to the outside (atmosphere) through an exhaust processing device (not shown). The main discharge pipe 32 is provided with a sub-discharge pipe 34 that is branched from the vicinity of the drying chamber 26 in parallel. In the portion of the main discharge pipe 32 that is in parallel with the sub discharge pipe 34, a first discharge on-off valve 32a and a first opening degree adjusting valve 32b are arranged in series. Further, in the sub-discharge pipe 34, a second discharge on-off valve 34a and a second opening degree adjusting valve 34b are arranged in series. As shown in FIG. 3, the inner diameter of the main discharge pipe 32 is larger than the inner diameter of the sub discharge pipe 34.

In this embodiment, the volume of the internal space of the drying chamber 26 is 5 m ³ , the inner diameter of the main supply pipe 28 and the auxiliary supply pipe 30 is 12.7 mm, the inner diameter of the main discharge pipe 32 is 50 mm, and the inner diameter of the auxiliary discharge pipe 34 is 20 mm. It was. When the first supply on / off valve 28a and the first discharge on / off valve 32a are opened and the second supply on / off valve 30a and the second discharge on / off valve 34a are closed, the internal pressure of the drying chamber 26 is 500 Pa higher than the atmospheric pressure. The first flow rate adjustment valve 28b and the first opening degree adjustment valve 32b were adjusted so that the flow rate of nitrogen gas was 450 L / min. When the first supply on / off valve 28a and the first discharge on / off valve 32a are closed and the second supply on / off valve 30a and the second discharge on / off valve 34a are opened, the internal pressure of the drying chamber 26 is 500 Pa higher than the atmospheric pressure. The second flow rate adjustment valve 30b and the second opening degree adjustment valve 34b were adjusted so that the flow rate of nitrogen gas was 30 L / min. A nitrogen cylinder filled with nitrogen gas having a dew point of −70 ° C. and an oxygen concentration of less than 1 ppm was used.

  When purging the drying chamber 26 with nitrogen gas, first, the shutter 27 (see FIG. 1) of the drying chamber 26 is closed. Next, the first supply on / off valve 28a and the first discharge on / off valve 32a are opened, and the second supply on / off valve 30a and the second discharge on / off valve 34a are closed. Then, nitrogen gas is supplied from the main supply pipe 28 to the upper part of the drying chamber 26 at a flow rate of 450 L / min in a state where the internal pressure of the drying chamber 26 is 500 Pa higher than the atmospheric pressure. Further, the internal gas in the drying chamber 26 is discharged from the lower portion of the drying chamber 26 to the outside through the main discharge pipe 32. At this time, the nitrogen gas flows down-flowing from the top to the bottom in the drying chamber 26. In this state, the dew point and the oxygen concentration in the internal space of the drying chamber 26 are monitored, and when the dew point is a predetermined temperature (for example, −60 ° C.) or lower and the oxygen concentration is a predetermined concentration (for example, 100 ppm) or lower, nitrogen gas replacement is performed. Consider completed. The above process is called a gas replacement process. Under the conditions of this embodiment, it takes about 12 hours to complete the replacement of nitrogen gas.

  When the gas replacement step is completed, the first supply on / off valve 28a and the first discharge on / off valve 32a are closed, and the second supply on / off valve 30a and the second discharge on / off valve 34a are opened. Then, with the internal pressure of the drying chamber 26 being 500 Pa higher than the atmospheric pressure, nitrogen gas is supplied from the sub supply pipe 30 to the upper portion of the drying chamber 26 at a flow rate of 30 L / min. Further, the internal gas in the drying chamber 26 is discharged to the outside through the sub-discharge pipe 34 from the lower portion of the drying chamber 26. Also in this case, the nitrogen gas flows down from the top to the bottom of the drying chamber 26. In this state, the dew point and oxygen concentration in the internal space of the drying chamber 26 are monitored to maintain an atmosphere where the dew point is a predetermined temperature (for example, −60 ° C.) or lower and the oxygen concentration is a predetermined concentration (for example, 100 ppm) or lower. Check. The above process is called an atmosphere maintenance process. If this atmosphere is not maintained for some reason, the process proceeds to the gas replacement step.

  According to the nitrogen gas purging method of this embodiment described above, the flow rate of nitrogen gas in the atmosphere maintaining step is smaller than the flow rate of nitrogen gas in the gas replacement step. Therefore, compared with the case where the flow rate of nitrogen gas in the atmosphere maintaining step is the same as the flow rate of nitrogen gas in the gas replacement step, the amount of nitrogen gas used is suppressed.

  In addition, a main discharge pipe 32 having a large diameter is used in a gas replacement process in which the flow rate of nitrogen gas is relatively large, and a sub-discharge pipe 34 having a small diameter is used in an atmosphere maintaining process in which the flow rate of nitrogen gas is relatively small. Here, if the main discharge pipe 32 having a large diameter is used in the atmosphere maintaining step, the flow rate is small, and the atmosphere in the internal space of the drying chamber 26 may be deteriorated. The cause of this is that a back flow from the main discharge pipe 32 occurs, or a gas not sufficiently substituted with nitrogen gas remains in the puddle (portion surrounded by a dotted line in FIG. 3) in the main discharge pipe 32 and diffuses. It seems to be to do. However, in this embodiment, since the sub-discharge pipe 34 having a diameter smaller than that of the main discharge pipe 32 is used in the atmosphere maintaining step, the atmosphere does not deteriorate.

  Furthermore, in the gas replacement step and the atmosphere maintaining step, the internal pressure of the drying chamber 26 is set to be higher by 500 Pa than the atmospheric pressure, so that the internal space of the drying chamber 26 can be replaced with an inert gas in a relatively short time, It is easy to maintain the atmosphere after replacement. On the other hand, for example, when the internal pressure of the drying chamber 26 is made 30 Pa higher than the atmospheric pressure in the gas replacement step, the replacement of nitrogen gas is not completed even after 20 hours. Specifically, as shown in FIG. 4, in the gas replacement step of the drying chamber 26, when the internal pressure is set to 30 Pa higher than the atmospheric pressure and the flow rate is set to 20 L / min, the dew point is −60 even after 20 hours. However, when the internal pressure was increased by 500 Pa from the atmospheric pressure and the flow rate was 20 L / min, the dew point decreased to -60 ° C. or less after 12 hours. became. The oxygen concentration became 100 ppm or less within 2 hours regardless of whether the internal pressure was 30 Pa higher than the atmospheric pressure or 500 Pa higher. Therefore, regardless of whether the internal pressure is 30 Pa higher than the atmospheric pressure or 500 Pa higher, the condition that the replacement of nitrogen gas is finally completed (here, the dew point is −60 ° C. or lower and the oxygen concentration is 100 ppm or lower) It was found that the replacement of nitrogen gas was completed in a shorter time in the latter.

  For reference, in the gas replacement process of the drying chamber 26, when the internal pressure was increased by 30 Pa from the atmospheric pressure and the flow rate was 20 L / min, the oxygen concentration was monitored for 20 hours. After 6 hours, the oxygen concentration stopped decreasing at 10 to 12 ppm. However, when the internal pressure was increased by 500 Pa from the atmospheric pressure without changing the flow rate after 20 hours, the oxygen concentration rapidly decreased to 2 to 3 ppm (see FIG. 5). Also, after monitoring the oxygen concentration up to 20 hours at an internal pressure of 30 Pa higher than the atmospheric pressure and a flow rate of 20 L / min, when the internal pressure was increased by 100 Pa from the atmospheric pressure without changing the flow rate, the oxygen concentration decreased to 6 to It became 7 ppm (refer FIG. 6). This means that even when the flow rate of nitrogen gas is the same, when the internal pressure is increased by 100 Pa (preferably 500 Pa) from the atmospheric pressure, the drying chamber 26 can be made more quickly than when the internal pressure is increased by 30 Pa from the atmospheric pressure. This suggests that nitrogen can be purged.

  Furthermore, since the sub discharge pipe 34 is branched from the main discharge pipe 32, the main discharge pipe 32 is unlikely to accumulate. That is, when the main discharge pipe 32 and the sub discharge pipe 34 are individually connected to the drying chamber 26, when the first discharge opening / closing valve 32 a is closed, the area from the drying chamber 26 to the closed position of the main discharge pipe 32 is blown up. It may become difficult to maintain the atmosphere. On the other hand, in the present embodiment, since the sub-discharge pipe 34 is connected between the drying chamber 26 and the closed position of the main discharge pipe 32, the above-described blowing-up hardly occurs.

  Further, since the nitrogen gas flows from the top to the bottom in the internal space of the drying chamber 26, even if there is dust in the internal space, the dust is suppressed from above without rising. As a result, the inside of the drying chamber 26 can be kept clean.

  Furthermore, since the internal space of the drying chamber 26 is a space for heat-treating the substrate on which the organic thin film has been formed, it is highly necessary to replace it with an inert gas such as nitrogen gas. That is, when heat-treating such a substrate, if oxygen or water is present, they may cause a chemical reaction with the organic thin film and deteriorate characteristics. For this reason, it is highly necessary to replace with an inert gas.

  Furthermore, when the drying chamber 26 is once evacuated and then purged with nitrogen gas, pressure resistance and sealability that can withstand the vacuum state are required. Since pressure resistance and sealing performance to maintain a high pressure of ˜1000 Pa are only required, the cost is not increased accordingly.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the main supply pipe 28 is used in the gas replacement process and the sub supply pipe 30 is used in the atmosphere maintaining process. However, the sub supply pipe 30 is eliminated and only the main supply pipe 28 is used. A mass flow controller may be attached to the main supply pipe 28 instead of the supply on / off valve 28a and the first flow rate adjustment valve 28b, and the gas supply amount may be automatically adjusted by the mass flow controller.

  In the embodiment described above, the internal pressure of the gas replacement step and the atmosphere maintaining step is set to a fixed value (atmospheric pressure + 500 Pa). However, the internal pressure of the gas replacement step is not a fixed value and is a step with time in a range higher than the atmospheric pressure. May be higher. For example, the internal pressure may be atmospheric pressure + 100 Pa for the first several hours of the gas replacement step, and thereafter atmospheric pressure + 1000 Pa.

  In the above-described embodiment, the workpiece processing apparatus 10 includes three chambers, but may include only the drying chamber 26.

DESCRIPTION OF SYMBOLS 10 Work processing apparatus, 12 Substrate rack, 14 Preparation chamber, 16 Outer shutter, 18 Inner shutter, 20 Substrate transport unit, 20a Hand member, 22 Transport chamber, 24 Substrate rack, 26 Drying chamber, 27 Shutter, 28 Main supply pipe, 28a Supply Open / Close Valve, 28b Flow Control Valve, 30 Sub Supply Pipe, 30a Supply Open / Close Valve, 30b Flow Control Valve, 32 Main Discharge Pipe, 32a Discharge Open / Close Valve, 32b Opening Adjust Valve, 34 Sub Discharge Pipe, 34a Discharge Open / Close Valve , 34b Opening adjustment valve

Claims (5)

Working space,
A supply pipe for supplying an inert gas to the working space;
A main discharge pipe for discharging the internal gas of the working space;
A sub-discharge pipe that discharges internal gas in the working space with a smaller diameter than the main discharge pipe;
An inert gas purge method for filling the work space of the workpiece processing apparatus with an inert gas,
(A) Gas replacement step of adjusting the supply amount from the supply pipe and the discharge amount from the main discharge pipe so that the internal pressure of the work space becomes higher than the atmospheric pressure with the sub-discharge pipe closed. When,
(B) After the gas replacement step, with the main discharge pipe closed, the internal pressure of the work space is higher than atmospheric pressure, and the flow rate is smaller than that in the gas replacement step. An atmosphere maintaining step for adjusting the supply amount from the supply pipe and the discharge amount from the sub-discharge pipe;
An inert gas purge method comprising: In the gas replacement step and the atmosphere maintenance step, the internal pressure of the work space is set to be higher by 100 to 1000 Pa than atmospheric pressure.
The inert gas purging method according to claim 1. The sub-discharge pipe branches off from the main discharge pipe,
The inert gas purging method according to claim 1 or 2. The supply pipe is provided above the main discharge pipe and the sub discharge pipe.
The inert gas purging method of any one of Claims 1-3. The work space is a space for manufacturing or processing a substrate provided with an organic thin film,
The inert gas purging method of any one of Claims 1-4.