JP3739287B2 - Vacuum drying method and coating film forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for forming a coating film by applying, for example, a coating liquid for a protective film of a device to a substrate to be processed such as a semiconductor wafer or an LCD substrate (glass substrate for liquid crystal display).
[0002]
[Prior art]
As one of semiconductor manufacturing processes, there is a process of applying polyimide on a substrate such as a semiconductor wafer in order to form a protective film or an interlayer insulating film of a semiconductor device. As one method of this coating treatment, a chemical solution in which polyimide is dissolved in a solvent is further diluted with a solvent before coating. For example, the wafer W is rotated as shown in FIG. A method is being studied in which the coating liquid is discharged onto the surface of the wafer W while being gradually moved in the direction, and the coating liquid is spirally applied in the manner of a single stroke.
[0003]
As a solvent for dissolving polyimide, the above-mentioned method is carried out because a low-volatility solvent is used or the solvent is quickly removed from the wafer surface to ensure the film thickness uniformity of the coating film. In this case, it is considered preferable to apply the coating liquid onto the wafer and immediately carry it into a vacuum drying unit to perform vacuum drying. FIG. 10 is a view showing a conventional vacuum drying unit. In the figure, reference numeral 12 denotes a sealed container composed of a lid 13 and a mounting portion 14, and an opening 13 a is formed in the ceiling of the lid 13. The opening 13 a communicates with a vacuum pump 16 provided outside the coating film forming apparatus via the exhaust pipe 15 so that the inside of the sealed container 12 can be depressurized. In such an apparatus, the wafer W is mounted on the mounting table 14, the wafer W is heated by a heating means (not shown), the vacuum pump 16 is operated, and the inside of the sealed container 12 is depressurized to thereby reduce the surface of the wafer W. For example, a solvent such as NMP is volatilized (dried), and the volatilized solvent is sucked to the vacuum pump 16 side so that the polyimide component in the coating liquid remains on the surface of the wafer W.
[0004]
[Problems to be solved by the invention]
However, the vacuum pump 16 used in the reduced-pressure drying apparatus is provided on the clean room side outside the coating film forming apparatus. Therefore, the solvent that volatilizes and is sucked to the vacuum pump 16 side during the reduced-pressure drying is stored in the exhaust pipe 15. In the middle, for example, condensation occurs under the influence of the atmosphere on the clean room side maintained at about 23 ° C.
[0005]
Although the solvent condensed in this manner volatilizes again from the adhesion site, the amount of the solvent remaining in the exhaust pipe 15 gradually increases because the amount of new condensation is larger than the volatilized amount of the condensed solvent. It will be. On the other hand, the exhaust flow rate in the vacuum pump 16 is kept constant, and the ratio of dew condensation in the entire volatilized solvent sucked by the vacuum pump 16 gradually increases. Therefore, the time required to reduce the pressure in the sealed container 12 to the pressure p1 necessary for drying the coating solution is t1 in the first process as shown by the solid line in FIG. As time increases, this time gradually increases. For example, at the time of processing the nth sheet, it takes t1 + α as shown by a dotted line, and sufficient drying cannot be performed within a predetermined time, resulting in a decrease in throughput.
[0006]
The present invention has been made based on such circumstances, and an object of the present invention is to provide a technique capable of obtaining a high throughput in a reduced-pressure drying apparatus for a substrate provided in a coating film forming apparatus, for example.
[0007]
[Means for Solving the Problems]
The reduced-pressure drying method according to the present invention includes a step of placing a substrate coated with a coating solution obtained by mixing a component of a coating film and a solvent in a sealed container;
A vacuum drying step in which the inside of the sealed container is evacuated through an exhaust path by a vacuum exhaust means to form a reduced-pressure atmosphere, and the solvent of the coating solution applied to the substrate is volatilized;
Carrying the substrate out of the sealed container;
In order to dry and remove the solvent that has volatilized from the substrate and has condensed in the exhaust passage, the solvent removal step of passing the drying gas through the exhaust passage while the sealed container is closed with the substrate not present in the container. It is characterized by including these.
[0008]
According to such a method, since the solvent condensed in the exhaust passage of the vacuum drying apparatus can be periodically removed, the amount of the solvent condensed during the vacuum drying of the substrate is reduced, and the drying process is promptly performed. Can be done. In this vacuum drying method, it is preferable to perform the vacuum drying process by heating the substrate, and the timing of performing the solvent removal process grasps in advance, for example, the relationship between how many substrates are dried and a certain delay in processing time occurs. In addition, it can be the time when the number of sheets subjected to the drying process reaches a set value.
[0009]
As a specific example of this solvent removal step, the gas supply path connected in the middle of the exhaust path and the vacuum exhaust means are communicated via the exhaust path and the exhaust path between the sealed container and the gas supply path is closed. An example is a method in which an inert gas such as nitrogen gas is supplied from the gas supply path into the exhaust path and sucked into the vacuum exhaust means.
[0010]
Further, the coating film forming apparatus according to the present invention includes a coating unit for coating a substrate with a coating liquid obtained by mixing a component of a coating film and a solvent,
An airtight container provided with a placement portion for placing a substrate therein;
Transport means for transporting the substrate between the coating unit and the sealed container;
A vacuum evacuation means connected to the sealed container through an exhaust path, and setting the inside of the sealed container to a reduced-pressure atmosphere to volatilize the solvent from the coating solution on the substrate;
A gas supply path connected in the middle of the sealed container or the exhaust path, for supplying a drying gas to the exhaust path and removing the condensed solvent in the exhaust path;
A flow path opening and closing section for opening and closing between the gas supply path and the vacuum exhaust means;
When it is determined that the amount of the condensed solvent in the exhaust passage has increased, the gas supply passage and the vacuum exhaust means are communicated with each other by controlling the flow passage opening and closing section in a state where the substrate is not present in the sealed container, and drying. And a control unit for causing the gas to flow through the exhaust path.
[0011]
The gas supply path is connected in the middle of the exhaust path, and the flow path opening / closing part is in communication between the gas supply path and the vacuum exhaust means and between the sealed container and the gas supply path is closed, and the gas supply path And a valve for selecting one of a closed state and a state where the sealed container and the vacuum evacuation unit communicate with each other. As a specific example of this valve, a three-way valve can be cited, and by providing this at the connection portion between the exhaust passage and the gas supply passage, the direction communicating with the two states described above can be switched.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A coating film forming apparatus for carrying out the coating film forming method according to the present invention will be described below. First, the overall configuration of this apparatus will be briefly described with reference to FIGS. In the figure, reference numeral 21 denotes a cassette station, for example, a delivery for transferring the wafer W between the cassette placement part 22 for placing a cassette C containing 25 wafers W and the placed cassette C. An arm 23 is provided. A processing unit S <b> 1 surrounded by a casing 24 is connected to the back side of the delivery arm 23. A main conveying means 25 is provided at the center of the processing unit S1, and a plurality of coating units 31 are provided on the right side, for example, so as to surround the main conveying means 25, and a heating / cooling system is provided on the left side, front side, and back side. Shelf units U1, U2, and U3 are stacked in multiple stages.
[0013]
The shelf units U1, U2, and U3 are configured by combining various units for performing pre-processing and post-processing of the coating unit 31, and the combination is, for example, in the coating unit 31 as shown in FIG. The wafer W having the coating solution coated on the surface is dried in a reduced pressure atmosphere, the reduced pressure drying unit 32 that volatilizes the solvent contained in the coating solution, the heating unit 33 that heats (bakes) the wafer W, and the wafer W is cooled. The cooling unit 34 is included. As for the shelf unit U3, a delivery unit 35 having a delivery table for delivering the wafer W is also incorporated. Further, the main transfer means 25 described above is configured to be movable up and down and back and forth and to rotate around a vertical axis, for example, and the wafer W between the units constituting the coating unit 31 and the shelf units U1, U2, and U3. It is possible to deliver.
[0014]
Next, the coating unit 31 will be described with reference to FIGS. Here, the casing that forms the exterior body of the coating unit 31 is omitted. In this casing (not shown), for example, a hollow case in which an opening (not shown) for loading and unloading the wafer W is formed on the side. A body 41 is provided therein, and a wafer holding unit 42 for holding the wafer W by vacuum suction from the back side and holding it horizontally, and supporting the wafer holding unit 42 from below, and supporting the wafer holding unit 42 during coating processing. A rotation mechanism 43 that rotates around the vertical axis is provided. A slit 44 extending in the X direction is formed in the ceiling portion of the case body 41, and above this slit 44, a nozzle 45 for supplying a polyimide liquid as a coating liquid is provided at a discharge hole 45a at the lower end. Is configured to be movable in the X direction by the drive unit 46 in a state of protruding into the case body 41 through the slit 44.
[0015]
Next, the configuration of the vacuum drying unit 32 will be described with reference to FIG. In the figure, reference numeral 51 denotes a mounting portion for mounting the wafer W, and a lid 52 is provided on the upper portion. The lid 52 can be raised and lowered by the action of an elevating mechanism 53 including a holding arm 53a, a drive unit 53b, and the like. The sealed container 5 is configured so that the atmosphere in which the wafer W is placed is sealed.
[0016]
Inside the mounting portion 51, three lift pins 54 are provided so as to pass through the wafer transfer arm to a wafer transfer arm (not shown). It can be moved up and down by a lifting unit 56 such as a cylinder. Further, in order to prevent the atmosphere in which the wafer W is placed from communicating with the atmosphere side through the through hole 54 a of the lift pin 53, a bellows 56 a is provided between the peripheral portion of the elevating plate 55 and the mounting portion 51. .
[0017]
A heater 57 composed of, for example, a resistance heating body for heating the wafer W at the time of drying under reduced pressure is embedded near the surface of the mounting portion 51. On the other hand, an opening 58 is formed in the ceiling 52 a of the lid 52 so that the atmosphere in the hermetic container 5 can be sucked, and in the space facing the wafer W in the lid 52, the ceiling 52 a is placed on the placement unit 51. A baffle plate 59, which is a plate-like rectifying member, is provided so as to face the wafer W to be placed and to have a gap in both the ceiling 52a and the side wall 52b of the lid body 52. A uniform exhaust flow is formed along the inner wall surface of the body 52.
[0018]
The opening 58 is connected to an exhaust pipe 6 that forms an exhaust path made of, for example, stainless steel. The other end of the exhaust pipe 6 is a housing (not shown) of the vacuum drying unit 32 and a housing of the processing unit S1. 24 is connected to a vacuum pump 61 which is a vacuum exhaust means provided in a clean room, for example, via a valve V1. The exhaust pipe 6 stands vertically from the lid 52 and is further bent horizontally, and a gas supply path 6a for supplying a drying gas into the exhaust pipe 6 is connected to the bent portion. The other end side of the gas supply path 6a is connected to the gas supply means 62 via the valve V2.
[0019]
If the exhaust path from the bent portion to the sealed container 5 is given a reference numeral 6b, the bent portion is a flow that seals one of the gas supply path 6a and the exhaust path 6b and opens the other. A three-way valve 63 forming a path opening / closing part is provided, and the gas supply path 6a side is sealed to allow the hermetic container 5 and the vacuum pump 61 to communicate with each other, and the exhaust path 6b side is sealed to supply gas. The means 62 and the vacuum pump 61 are configured to communicate with each other. By the way, the position where the three-way valve 63 is provided in the exhaust pipe 6 is preferably upstream of the site where the solvent in the coating solution volatilized by drying under reduced pressure is condensed due to the influence of the clean room atmosphere. Is accumulated at the horizontal portion of the exhaust pipe 6, the three-way valve 63 is arranged at the bent portion so that the drying gas can be supplied into the exhaust pipe 6. The flow direction (gas supply path 6a, exhaust path 6b) of the exhaust pipe 6 sealed by the three-way valve 63 can be switched based on a control signal from the control unit 7. .
[0020]
Next, the operation of the above embodiment will be described. First, when the cassette C is loaded into the cassette station 21, the wafer W is taken out by the transfer arm 23. Then, the wafer W is transferred from the transfer arm 23 to the main transfer means 25 via the transfer unit 35 in the shelf unit U2, and is transferred into the coating unit 31. The wafer W carried into the coating unit 31 is adsorbed on the back side by the wafer holder 42 and is held substantially horizontally. Then, after positioning the nozzle 45 above the center of the wafer W, the discharge of the polyimide liquid is started, and the nozzle 45 is gradually moved from the center of the rotating wafer W toward the outer edge side to draw a spiral pattern.
[0021]
Next, the wafer W on which the resist solution has been applied is transferred to the vacuum drying unit 32 by the main transfer means 25. When the wafer W is loaded into the vacuum drying unit 32, first, an arm (not shown) of the main transfer means 25 enters above the mounting portion 51 with the lid 52 raised, and lift pins 54 are lifted from the arm. After receiving the wafer W, the lift pins 54 are lowered.
[0022]
Thereafter, the lid 52 is lowered to form the sealed container 5 and drying under reduced pressure is started. At this time, the three-way valve is in a state in which the gas supply path 6a is sealed and the hermetic container 5 and the vacuum pump 61 are in communication with each other. The heater 57 heats the wafer W to about 50 ° C., for example, and opens the valve V1 for vacuum. The suction in the sealed container 5 is started by the pump, and the atmosphere in which the wafer W is placed is set to a reduced pressure atmosphere of 13.3 Pa, for example. The polyimide liquid (coating liquid) applied to the surface of the wafer W is obtained by dissolving a polyimide component, which is a component of the coating film, in a solvent such as NMP (N-methylpyrrolidone). Is volatilized violently and is sucked into the exhaust pipe 6 through the opening 58 and the exhaust path 6b. At this time, since the exhaust flow in the sealed container 5 is formed so as to bypass the baffle plate 59 as described above, the solvent vapor volatilized from the wafer W hits the baffle plate 59 and changes its direction outward. Together with this exhaust flow, it spreads uniformly in the radial direction toward the opening 58.
[0023]
Thus, the surface of the wafer W is dried in a short time, and after the drying process is completed, the inside of the sealed container 5 is purged with, for example, dry air or nitrogen gas via a gas supply source (not shown), and the inside of the sealed container 5 is returned to atmospheric pressure. . Then, the lid body 52 is raised, and the wafer W is unloaded by the main transfer means 25 through a process reverse to the order of loading into the reduced-pressure drying unit 32.
[0024]
Here, returning to the reduced-pressure drying unit 32 again, the solvent removal work in the exhaust pipe 6 will be described with reference to FIG. First, as shown in FIG. 7 (a), immediately after the start of the treatment, the volatilized solvent is sucked to the vacuum pump 61 side, and the drying under reduced pressure is performed within a predetermined time. However, since the horizontal portion is affected by the temperature on the clean room side maintained at about 23 ° C., for example, a very small amount of the volatilized solvent is condensed in this portion and adheres to the exhaust pipe 6.
[0025]
Condensed solvent will volatilize again, but on the other hand, new condensation has occurred, and the amount of new condensation exceeds the volatilization amount of the solvent once condensed, so while repeating the vacuum drying process many times, As shown in FIG. 7B, the amount of solvent R accumulated in the exhaust pipe 6 increases. At this time, the control unit 7 counts the number of wafers W that have been dried under reduced pressure, and the reduced pressure drying process is temporarily stopped when it is recognized that the number has reached a certain amount.
[0026]
Then, the control unit 7 switches the three-way valve 63 to seal the exhaust passage 6b, communicate the gas supply passage 6a with the exhaust pipe 6, and perform control to open the valves V1 and V2. As a result, an inert gas such as nitrogen gas is supplied from the gas supply means 62 into the gas supply path 6a, and the nitrogen gas filled in the gas supply path 6a and the exhaust pipe 6 is sucked by the vacuum pump 61. As shown in FIG. 7C, the solvent R adhering in the exhaust pipe 6 is sucked to the vacuum pump 61 side, and the solvent in the exhaust pipe 6 is removed. The time required for the removal operation is determined based on, for example, the relationship between the number of wafers W processed before the removal operation, which has been grasped in advance, and the time required for solvent removal according to the number of wafers.
[0027]
After the removal operation is performed for a predetermined time in this way, the supply and suction (discharge) of the nitrogen gas in the exhaust pipe 6 are stopped by closing the valves V1 and V2, and the three-way valve 63 before the start of the removal operation is stopped. Return to the state (switch). Then, the number of processed wafers counted before the start of work is returned to zero, and the reduced-pressure drying process is resumed.
[0028]
According to the above-described embodiment, since the solvent condensed on the exhaust pipe 6 of the reduced pressure drying unit 32 can be periodically removed, the amount of volatilized from the condensed solvent when the wafer W is dried under reduced pressure is reduced. For this reason, the solvent can be volatilized actively from the coating film on the wafer W, and the drying process can be performed quickly, so that a high throughput can be obtained.
[0029]
When a plurality of reduced-pressure drying units 32 are provided in the coating film forming apparatus as in the above-described embodiment, the control unit 7 preferably performs the following control, for example. That is, for example, when the main transfer means 25 tries to transfer the wafer W from the coating unit 31 to one vacuum drying unit 32, when the solvent removal operation in the exhaust pipe 6 is performed in the one vacuum drying unit 32, The main transfer means 25 transfers the wafer W to another vacuum drying unit 32 other than the vacuum drying unit 32 without waiting for the completion of the solvent removal operation.
[0030]
The wafer W on which the coating liquid has been applied needs to be transported to the vacuum drying unit 32 in as short a time as possible while maintaining the state of the liquid film on the surface, and the solvent needs to be volatilized uniformly and quickly from the entire surface. . For this reason, by controlling as described above, the time for waiting the coated wafer W can be reduced, and the in-plane uniformity of film thickness and film quality can be increased.
[0031]
Moreover, you may comprise the reduced pressure drying unit 32 as shown, for example in FIG. In the present embodiment, in the vacuum drying unit 32, for example, a wafer transfer means 80 that can freely move up and down, move forward and backward, and rotate around a vertical axis, and a standby section 8 on the lower side of the sealed container 5 are provided. For example, reference numeral 8 is configured such that a mounting table 82 is provided in a case 81 that is adjusted in temperature and humidity so as to suppress volatilization of the solvent in the coating solution, or is further filled with solvent vapor. In addition, 81a is a door.
[0032]
According to such a configuration, for example, when the solvent removal operation of the exhaust pipe 6 is performed in the vacuum drying unit 32, the wafer W is once carried into the standby unit 8 by the main transfer unit 25, and the wafer W While the state of the liquid film applied on the surface is maintained, the completion of the solvent removal operation is waited, and after the solvent removal operation is completed, the wafer W is quickly transferred to the sealed container 5 and transferred to vacuum drying. be able to.
[0033]
However, in the present embodiment, the wafer transfer means 80 may not be provided, and the main transfer means 25 may transfer the wafer W from the standby unit 8 to the sealed container 5. However, if the wafer transfer means 80 is used, the main transfer means 25 may be used. The burden on the transport means 25 is reduced, and the throughput can be increased. The standby unit 8 may be used not only when the solvent removal operation is performed, but also for waiting the wafer W when another vacuum drying unit 32 provided in the coating film forming apparatus is operating, for example. Good.
[0034]
In addition, after drying under reduced pressure, in the sealed container 5, before the wafer 52 is lifted and the wafer W is taken out, the sealed container 5 is purged with air or nitrogen gas to return to atmospheric pressure as described above. However, the purge gas may be supplied from the gas supply means 62 or may be supplied via a different path from the gas supply means 62.
[0035]
That is, in the former case, the direction of the three-way valve 63 that communicated the vacuum pump 61 and the sealed container 5 during the drying under reduced pressure is switched, the gas supply means 62 and the sealed container 5 are communicated, and the purge in the sealed container 5 is performed. The pressure in the sealed container 5 is returned to atmospheric pressure. On the other hand, in the latter case, although not shown here, for example, a purge gas supply means is provided in the vicinity of the ceiling of the lid body 52 in FIG. Purge with, for example, nitrogen gas is performed until the inside of 5 becomes atmospheric pressure.
[0036]
In the above description, the timing at which the solvent in the supply pipe 6 is removed is determined based on the number of wafers subjected to the drying process in the control unit 7 and is determined based on this number. For example, a monitoring means such as a CCD camera is provided to grasp the amount of solvent adhering in the exhaust pipe 6 and the time when the amount exceeds a certain amount. Alternatively, the correlation between the number of processed sheets and the time required for drying is grasped in advance, and the number of wafers to be processed is determined in advance before solvent removal is necessary based on the data. You may do it.
[0037]
In removing the solvent, the gas supplied from the gas supply means 62 is not limited to nitrogen gas, and may be, for example, dry air. The gas may be warmed so that the solvent is easily volatilized.
[0038]
【The invention's effect】
As described above, according to the present invention, a high throughput can be obtained in a reduced-pressure drying apparatus for a substrate provided in a coating film forming apparatus.
[Brief description of the drawings]
FIG. 1 is a plan view showing the overall structure of a coating film forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an overall structure in the embodiment.
FIG. 3 is a schematic cross-sectional view showing a configuration of a shelf unit used in the embodiment.
FIG. 4 is a longitudinal sectional view for explaining a coating unit used in the embodiment.
FIG. 5 is a plan view for explaining the coating unit.
FIG. 6 is a longitudinal sectional view showing a reduced pressure drying unit incorporated in the shelf unit.
FIG. 7 is an explanatory diagram for explaining the operation of the present embodiment;
FIG. 8 is an explanatory diagram for explaining another embodiment according to the present invention.
FIG. 9 is an explanatory diagram for explaining a conventional invention.
FIG. 10 is a schematic cross-sectional view illustrating a vacuum drying apparatus according to a conventional invention.
FIG. 11 is an explanatory diagram for explaining a problem in the conventional invention.
[Explanation of symbols]
C cassette W wafer S1 processing unit U1, U2, U3 shelf unit 21 cassette station 25 main transfer means 31 coating unit 32 vacuum drying unit 41 case body 42 wafer holding unit 43 rotating mechanism 45 nozzle 46 driving unit 5 sealed container 51 mounting unit 52 Lid 6 Exhaust pipe 6a Gas supply path 6b Exhaust path 61 Vacuum pump 62 Gas supply means 63 Three-way valve

Claims (15)

Placing a substrate coated with a coating solution obtained by mixing a component of a coating film and a solvent in a sealed container; and
A vacuum drying step of evacuating the inside of the sealed container through an exhaust path by a vacuum exhaust means to form a reduced pressure atmosphere, and volatilizing the solvent of the coating solution applied to the substrate;
Carrying the substrate out of the sealed container;
In order to dry and remove the solvent that has volatilized from the substrate and has condensed in the exhaust passage, the solvent removal step of passing the drying gas through the exhaust passage while the sealed container is closed with the substrate not present in the container. And a vacuum drying method comprising the steps of:   2. The reduced-pressure drying method according to claim 1, wherein the solvent removing step is performed after the number of substrates subjected to the drying process reaches a preset number.   The solvent removal step is a step of removing the solvent condensed in the exhaust passage to the vacuum exhaust means side while being sucked by the vacuum exhaust means while supplying the gas for drying from the middle of the exhaust passage or from the gas supply passage connected to the sealed container The reduced-pressure drying method according to claim 1 or 2, wherein   The solvent removal step is characterized in that the gas supply path connected in the middle of the exhaust path and the vacuum exhaust means are communicated via the exhaust path and the exhaust path between the sealed container and the gas supply path is closed. The reduced-pressure drying method according to claim 1, 2, or 3.   5. The coating film forming method according to claim 1, wherein the drying gas used in the solvent removing step is an inert gas.   6. The method for forming a coating film according to claim 1, wherein the step of drying under reduced pressure includes a step of heating the substrate. It has a process to grasp the amount of solvent adhering to the exhaust passage,
  7. The method of forming a coating film according to claim 1, wherein the solvent removing step is performed when the amount of the solvent adhering to the exhaust passage becomes a certain amount or more. The coating film formation according to any one of claims 1 to 6, wherein during the solvent removal step, the substrate on which the coating liquid has been applied by the coating unit is once carried into the standby unit and waited. Method. 9. The coating film forming method according to claim 8, further comprising a step of setting a solvent atmosphere to an atmosphere in which the substrate in the standby unit is placed. A coating unit for coating a substrate with a coating solution obtained by mixing a component of a coating film and a solvent;
An airtight container provided with a placement portion for placing a substrate therein;
Transport means for transporting the substrate between the coating unit and the sealed container;
A vacuum evacuation means connected to the sealed container via an exhaust path, and setting the inside of the sealed container in a reduced pressure atmosphere to volatilize the solvent from the coating solution on the substrate;
A gas supply path connected in the middle of the sealed container or the exhaust path, for supplying a drying gas to the exhaust path and removing the solvent condensed in the exhaust path;
A flow path opening and closing section for opening and closing between the gas supply path and the vacuum exhaust means;
When it is determined that the amount of solvent condensed in the exhaust passage has increased, the gas supply passage and the vacuum exhaust means are communicated by controlling the flow passage opening and closing section in a state where the substrate is not present in the sealed container, and is dried. And a control unit for causing the gas for use to flow through the exhaust passage. 11. The coating film formation according to claim 10, wherein the time when it is determined that the amount of the solvent condensed in the exhaust passage is increased is a time when the number of substrates subjected to the drying process reaches a preset number. apparatus. Provide monitoring means to grasp the amount of solvent adhering to the exhaust passage,
12. The coating film forming apparatus according to claim 11, wherein the control unit determines that the amount of the solvent condensed in the exhaust passage has increased based on the monitoring result of the monitoring unit. The gas supply path is connected in the middle of the exhaust path,
The flow path opening / closing part communicates between the gas supply path and the vacuum exhaust means, closes the space between the sealed container and the gas supply path, and closes the space between the gas supply path and the vacuum exhaust means. The coating film forming apparatus according to any one of claims 10 to 12 , further comprising a valve for selecting one of a state in which the sealed container and the vacuum evacuation unit communicate with each other. It has a standby part for placing the substrate once and making it wait,
The control unit is configured to transfer the substrate to the standby unit while supplying the drying gas to the exhaust path and removing the solvent in the exhaust path. Item 14. The coating film forming apparatus according to any one of Items 10 to 13 .   15. The coating film forming apparatus according to claim 14, wherein the standby unit is configured so that an atmosphere in which the substrate is placed is a solvent atmosphere.

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