CN216605955U

CN216605955U - Decompression drying device

Info

Publication number: CN216605955U
Application number: CN202122921233.3U
Authority: CN
Inventors: 高村幸宏
Original assignee: Screen Holdings Co Ltd
Current assignee: Screen Holdings Co Ltd
Priority date: 2020-11-30
Filing date: 2021-11-25
Publication date: 2022-05-27
Anticipated expiration: 2031-11-25
Also published as: JP7555804B2; JP2022086765A

Abstract

The utility model provides a reduced pressure drying device capable of uniformly drying a coating layer formed on the upper surface of a substrate. The decompression drying device (1) is provided with a chamber (10), a stage (20), a plurality of exhaust ports (16a) - (16d), a decompression mechanism (30), and a control unit (80). The pressure reducing mechanism (30) has a plurality of independent valves (Va) to (Vd) for independently adjusting the amounts of exhaust gas from the plurality of exhaust ports (16a to 16 d). The control unit (80) sequentially changes a part of the independent valves (Va) - (Vd) so as to change the opening/closing state or the opening degree of some of the independent valves each time when the pressure in the chamber (10) is reduced. Thus, the amounts of exhaust gas from the plurality of exhaust ports (Va) to (Vd) are sequentially switched. By doing so, the direction of the airflow formed along the upper surface of the substrate (9) is changed. As a result, uneven drying due to the solvent vapor can be suppressed. Therefore, the coating layer on the upper surface of the substrate (9) can be uniformly dried.

Description

Decompression drying device

Technical Field

The present invention relates to a reduced-pressure drying apparatus for drying a coating layer formed on an upper surface of a substrate by reducing pressure.

Background

Conventionally, in a process for manufacturing an organic EL display device, a coating layer as a hole injection layer, a hole transport layer, or a light emitting layer is formed on an upper surface of a substrate. The coating layer is partially coated on the upper surface of the substrate by an ink jet device. The substrate on which the coating layer is formed is conveyed to a chamber of a reduced-pressure drying apparatus and subjected to a reduced-pressure drying process. Thereby, the solvent contained in the coating layer is vaporized to dry the coating layer.

The decompression drying device is provided with a chamber for accommodating the substrate and a decompression mechanism for sucking gas from the chamber. For example, patent document 1 describes a conventional vacuum drying apparatus.

Patent document 1: japanese patent laid-open publication No. 2018-49806.

In a conventional decompression drying apparatus, an exhaust port for exhausting gas in a chamber is provided on a bottom surface of the chamber. This is to form a uniform gas flow on the upper surface side of the substrate when the chamber is depressurized. However, in the upper surface of the substrate, the solvent in the coating layer vaporizes with the reduced pressure in the coating region covered with the coating layer, whereas the solvent does not vaporize in the non-coating region not covered with the coating layer. Therefore, when the gas flow direction on the upper surface side of the substrate is always constant, the degree of progress of drying at the edge portion of the coating region differs between the portion where the gas flows from the non-coating region to the coating region and the portion where the gas flows from the coating region to the non-coating region due to the influence of the vapor of the solvent. As a result, the coating layer may be dried unevenly.

SUMMERY OF THE UTILITY MODEL

The present invention has been made in view of such circumstances, and an object thereof is to provide a reduced-pressure drying apparatus capable of uniformly drying a coating layer formed on an upper surface of a substrate.

In order to solve the above problem, a first aspect of the present invention is a reduced pressure drying apparatus for drying a solvent-containing coating layer formed on an upper surface of a substrate by reducing pressure, the apparatus including: a chamber for receiving a substrate; a stage supporting a substrate from below inside the chamber; a plurality of exhaust ports disposed in the chamber; a pressure reducing mechanism that sucks the gas in the chamber through the plurality of exhaust ports; and a control unit that controls the decompression mechanism. The pressure reducing mechanism has a plurality of independent valves for independently adjusting the amounts of exhaust gas from the plurality of exhaust ports. The control unit executes a switching process of sequentially changing a part of the plurality of independent valves so as to change an opening/closing state or an opening degree of the independent valves at a time.

The second utility model of this application is in the decompression drying device of the first utility model, it is a plurality of the gas vent be located by the below of the base plate that the objective table supported.

The third utility model of the present application is the decompression drying device of the first utility model or the second utility model, and is a plurality of the independent valve is the open-close valve, the mode that the control part was in proper order with closing some independent valves at every turn and opened other independent valves is right the independent valve changes some.

A fourth utility model of the present application is the decompression drying device of the third utility model, the control portion changes an independent valve in proper order with the mode of closing an independent valve at every turn and opening other independent valves.

The fifth utility model of the present application is the decompression drying device of the first utility model or the second utility model, and is a plurality of the independent valve is the aperture control valve that can adjust the aperture, the control part is in proper order right with the mode that makes the aperture of some independent valve be less than the aperture of other independent valves at every turn the independent valve changes some.

A sixth aspect of the present invention is the fifth aspect of the present invention, wherein the control unit sequentially changes the single independent valve so that the opening degree of the single independent valve is smaller than the opening degrees of the other independent valves at every time.

A seventh utility model of the present application is the decompression drying device of the first utility model or the second utility model, the decompression mechanism has one end and a plurality of independent piping that the gas vent is connected, and with a plurality of a main piping that the other end of independent piping is connected. The independent valves are provided in the plurality of independent pipes, respectively. The pressure reducing mechanism further includes a main valve that is provided in the main pipe and is capable of adjusting an opening degree.

An eighth utility model of the present application is the decompression drying device of the seventh utility model, wherein the control portion controls the opening of the main valve according to a plurality of the open/close state or the opening of the independent valve.

A ninth utility model of the present application is the decompression drying device of the first utility model or the second utility model, the control portion is at least in execute when the coating layer boils switching processing.

A tenth aspect of the present invention is the decompression drying device of the first or second aspect, wherein the substrate upper surface has a portion covered with the coating layer and a portion exposed from the coating layer.

According to the first utility model ~ the tenth utility model of this application, when decompressing in the cavity, switch over the displacement that comes from a plurality of gas vents in proper order. Thereby, the direction of the air flow formed along the upper surface of the substrate is changed. As a result, uneven drying caused by the solvent vapor vaporized from the coating layer can be suppressed. Therefore, the coating layer on the upper surface of the substrate can be uniformly dried.

In particular, according to the second invention of the present application, the gas in the chamber is exhausted from below the substrate. This makes it possible to uniformize the flow of the gas on the upper surface side of the substrate.

In particular, according to the fourth invention of the present application, the displacement can be ensured by closing only one independent valve.

In particular, according to the fifth aspect of the present invention, the gas flow formed along the upper surface of the substrate can be changed more gently than in the case of using the on-off valve.

In particular, according to the sixth invention of the present application, the displacement can be ensured by reducing only the opening degree of one independent valve.

In particular, according to the eighth invention of the present application, the change in the displacement of the entire decompression mechanism can be suppressed.

In particular, according to the ninth invention of the present application, it is possible to suppress the solvent vapor generated in a large amount by boiling of the coating layer from flowing in one direction. Therefore, uneven drying due to the solvent vapor can be suppressed.

Drawings

Fig. 1 is a longitudinal sectional view of a decompression drying device.

Fig. 2 is a transverse sectional view of the decompression drying device.

Fig. 3 is a perspective view of the substrate.

Fig. 4 is a block diagram schematically showing functions implemented in the control section.

Fig. 5 is a flowchart showing the flow of the reduced pressure drying process.

Fig. 6 is a diagram showing changes in the air pressure in the chamber.

Fig. 7 is a diagram showing a state in the chamber when the stage is disposed at the raised position.

Fig. 8 is a timing chart showing changes in the open/close states of four independent valves.

Fig. 9 is a partial longitudinal sectional view of the substrate.

Fig. 10 is a diagram showing a state in the chamber when the stage is disposed at the lowered position.

Fig. 11 is a timing chart showing changes in the open/close states of four independent valves according to a modification.

Fig. 12 is a longitudinal sectional view of a vacuum drying apparatus according to a modification.

Fig. 13 is a longitudinal sectional view of a vacuum drying apparatus according to a modification.

Description of reference numerals

1 decompression drying device

9 base plate

10 Chamber

11 bottom plate part

12 side wall part

13 top surface part

16a exhaust port

16b exhaust port

16c exhaust port

16d exhaust port

16f air supply port

20 object stage

21 support plate

22 support pin

23 lifting mechanism

30 decompression mechanism

31 exhaust pipe

32 vacuum pump

40 bottom surface fairing board

50 side fairing

51 top surface fairing

60 air supply mechanism

61 air supply pipe

70 pressure gauge

80 control part

90 coating layer

Va independent valve

Vb independent valve

Vc independent valve

Vd independent valve

Ve main valve

Vf air supply valve

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

< 1. construction of vacuum drying apparatus

Fig. 1 is a longitudinal sectional view of a decompression drying device 1 according to an embodiment of the present invention. Fig. 2 is a transverse sectional view of the decompression drying device 1. The vacuum drying apparatus 1 is an apparatus for performing vacuum drying processing on a substrate 9 in a manufacturing process of an organic EL display device. A rectangular glass substrate is used as the substrate 9. On the upper surface of the substrate 9, a coating layer 90 (see fig. 9) containing an organic material and a solvent is partially formed in advance. The coating layer 90 is dried by using the reduced-pressure drying apparatus 1, thereby forming a hole injection layer, a hole transport layer, or a light-emitting layer of the organic EL display device.

Fig. 3 is a perspective view of the substrate 9. The substrate 9 has a rectangular shape with different vertical and horizontal lengths in a plan view. As shown in fig. 3, a plurality of circuit regions a1 forming a circuit pattern of the organic EL display device are arranged on the upper surface of the substrate 9. In the example of fig. 3, four rectangular circuit regions a1 are arranged in a matrix of 2 rows and 2 columns on the upper surface of the substrate 9. However, the shape, number, and arrangement of the circuit regions a1 are not limited to this example. In the coating step before the reduced-pressure drying step, the coating layer 90 is formed in each circuit region a1 according to the circuit pattern by the ink jet device. Therefore, each circuit area a1 has a portion covered with the coating layer 90 and a portion exposed from the coating layer 90. In addition, a boundary area a2 between adjacent circuit areas a1 is a portion exposed from the coating layer 90.

As shown in fig. 1 and 2, the decompression drying apparatus 1 includes a chamber 10, a stage 20, a decompression mechanism 30, a bottom flow regulating plate 40, a side flow regulating plate 50, an air supply mechanism 60, a pressure gauge 70, and a control unit 80.

The chamber 10 is a pressure-resistant container having an internal space for housing the substrate 9. The chamber 10 is fixed to an apparatus frame, not shown. The chamber 10 has a flat rectangular parallelepiped shape. The chamber 10 has a substantially square-shaped bottom plate portion 11, four side wall portions 12, and a substantially square-shaped top surface portion 13. The four side wall portions 12 connect four edges of the bottom plate portion 11 with four edges of the top surface portion 13 in the up-down direction.

One of the four side wall portions 12 is provided with a carrying-in/carrying-out port 14 and a shutter 15 for opening and closing the carrying-in/carrying-out port 14. The shutter 15 is connected to a shutter drive mechanism 16 constituted by an air cylinder or the like. When the shutter drive mechanism 16 is operated, the shutter 15 moves between a closed position for closing the carrying-in/out port 14 and an open position for opening the carrying-in/out port 14. In a state where the shutter 15 is disposed at the closed position, the internal space of the chamber 10 is sealed. In a state where the shutter 15 is disposed at the open position, the substrate 9 can be carried into the chamber 10 and the substrate 9 can be carried out from the chamber 10 through the carrying-in and carrying-out port 14.

The stage 20 is a support portion that supports the substrate 9 inside the chamber 10. The stage 20 has a plurality of support plates 21. The plurality of support plates 21 are arranged at intervals in the horizontal direction. A plurality of support pins 22 are provided on the upper surface of each support plate 21. The substrate 9 is disposed above the plurality of support plates 21. The upper ends of the support pins 22 are in contact with the lower surface of the substrate 9, whereby the substrate 9 is supported in a horizontal posture.

The plurality of support plates 21 of the stage 20 are connected to an elevating mechanism 23. In order to avoid complication of the drawing, the lifting mechanism 23 is schematically shown in fig. 1, but the lifting mechanism 23 is actually constituted by an actuator such as an air cylinder. When the elevating mechanism 23 is operated, the stage 20 is moved vertically between a lowered position H1 (indicated by a solid line in fig. 1) and a raised position H2 (indicated by a two-dot chain line in fig. 1) higher than the lowered position H1. At this time, the plurality of support plates 21 move up and down as a whole.

The pressure reducing mechanism 30 is a mechanism that sucks gas from the internal space of the chamber 10 to reduce the pressure inside the chamber 10. As shown in fig. 1 and 2, the bottom plate 11 of the chamber 10 is provided with four exhaust ports 16a to 16 d. The four exhaust ports 16a to 16d are located below the substrate 9 supported by the stage 20 and below a bottom surface rectifying plate 40 described later. The pressure reducing mechanism 30 includes an exhaust pipe 31 connected to the four exhaust ports 16a to 16d, four independent valves Va to Vd, a main valve Ve, and a vacuum pump 32.

The exhaust pipe 31 includes four independent pipes 31a to 31d and one main pipe 31 e. One ends of the four independent pipes 31a to 31d are connected to the four exhaust ports 16a to 16d, respectively. The other ends of the four independent pipes 31a to 31d are joined together to form one pipe, and are connected to one end of the main pipe 31 e. The other end of the main pipe 31e is connected to a vacuum pump 32. Four independent valves Va to Vd are provided in the paths of the four independent pipes 31a to 31d, respectively. The main valve Ve is provided on the path of the main pipe 31 e.

In a state where the carrying-in/out port 14 is closed by the shutter 15, at least a part of the four independent valves Va to Vd and one main valve Ve are opened, and when the vacuum pump 32 is operated, the gas in the chamber 10 is discharged to the outside of the chamber 10 through the exhaust pipe 31. This can reduce the pressure in the internal space of the chamber 10.

The four independent valves Va to Vd are valves for independently adjusting the amounts of exhaust gas from the four exhaust ports 16a to 16 d. The individual valves Va to Vd according to the present embodiment are opening and closing valves that are switched between an open state and a closed state based on a command from the control unit 80. The main valve Ve is a valve for adjusting the total amount of exhaust gas from the four exhaust ports 16a to 16 d. The main valve Ve of the present embodiment is an opening degree control valve whose opening degree can be adjusted based on a command from the control unit 80.

In the decompression drying device 1, the four exhaust ports 16a to 16d are positioned below the substrate 9 supported by the stage 20. Therefore, the flow of the gas on the upper surface side of the substrate 9 can be made uniform as compared with the case where the gas discharge port is provided above the substrate 9. Therefore, uneven drying of the coating layer 90 formed on the upper surface of the substrate 9 can be suppressed.

The bottom flow regulating plate 40 is a plate for restricting gas flow when the pressure in the chamber 10 is reduced. The bottom surface rectifying plate 40 is located between the substrate 9 supported by the stage 20 and the bottom plate portion 11 of the chamber 10. More specifically, the bottom surface rectification plate 40 is located at the following positions: spaced apart from the stage 20 at the lowered position H1 by a distance, and spaced apart from the upper surface of the bottom plate 11 by a distance. Further, the bottom rectifying plate 40 is horizontally expanded along the upper surface of the bottom plate portion 11. The bottom flow rectification plate 40 is fixed to the bottom plate 11 of the chamber 10 via a plurality of support columns (not shown).

As shown in fig. 2, the bottom rectifying plate 40 is square in shape in plan view. In addition, the lengths of the sides of the bottom rectification plate 40 are longer than the long sides and the short sides of the rectangular substrate 9 in plan view. Therefore, regardless of the orientation of the substrate 9 disposed on the stage 20, the bottom surface rectifying plate 40 is larger than the substrate 9 in plan view.

The side flow rectification plate 50 is a plate for restricting gas flow when the pressure in the chamber 10 is reduced, together with the bottom flow rectification plate 40. The side flow rectification plates 50 are located between the substrate 9 supported by the stage 20 at the lowered position H1 and the side wall portion 12 of the chamber 10. More specifically, the side rectifying plates 50 are located at the following positions: outside the end of the substrate 9 supported by the stage 20 at the lowered position H1 with a gap therebetween and inside the inner surface of the side wall portion 12 with a gap therebetween. In the present embodiment, four side rectification plates 50 are arranged around the substrate 9 supported by the stage 20. Each side rectifying plate 50 extends along the inner surface of the side wall portion 12. Therefore, the four side flow rectification plates 50 are rectangular tubular flow rectification plates surrounding the base plate 9 as a whole. Further, the bottom flow rectification plate 40 and the four side flow rectification plates 50 are a box-shaped flow rectification plate having a bottom cylindrical shape as a whole.

When the internal space of the chamber 10 is depressurized, the gas in the chamber 10 is discharged to the outside of the chamber 10 through the space between the side flow regulating plate 50 and the side wall portion 12, the space between the bottom flow regulating plate 40 and the bottom plate portion 11, and the exhaust ports 16a to 16 d. By thus flowing the gas in the space away from the substrate 9, the gas flow formed in the vicinity of the substrate 9 can be reduced. In particular, the concentration of the gas flow on the peripheral edge portion of the substrate 9 can be suppressed. As a result, uneven drying of the coating layer 90 formed on the upper surface of the substrate 9 can be suppressed.

As shown in fig. 2, the box-shaped rectifying plate formed by the bottom rectifying plate 40 and the four side rectifying plates 50 is square in plan view. In addition, the length of each side of the box-shaped rectifying plate is longer than the length of the long side and the length of the short side of the rectangular substrate 9 in a plan view. Therefore, the gas flow in the chamber 10 can be made the same at the time of depressurization regardless of the orientation of the substrate 9 disposed on the stage 20. That is, the change in the gas flow in the chamber 10 due to the orientation of the substrate 9 can be suppressed.

As shown in fig. 2, the four exhaust ports 16a to 16d are located on the diagonal lines 41 of the square bottom rectifying plate 40 in the plan view. By doing so, the exhaust ports 16a to 16d can form air flows symmetrical with respect to the center of the bottom rectifying plate 40 (the intersection of the two diagonal lines 41). This enables a more uniform airflow to be formed inside the chamber 10.

The three side rectification plates 50 are fixed to the side wall portion 12 of the chamber 10. However, in order to secure the carrying-in and carrying-out path of the substrate 9, the remaining one of the side rectifying plates 50 is movable with respect to the side wall portion 12 and the bottom rectifying plate 40. For example, the one side rectifying plate 50 may be configured to move together with the shutter 15. By doing so, when the shutter 15 moves from the closed position to the open position, the side rectifying plate 50 also moves, and the carrying-in and carrying-out path of the substrate 9 can be secured.

However, when the movable side flow rectification plate 50 is in contact with another side flow rectification plate 50 or the bottom flow rectification plate 40, there is a possibility that dust is generated due to sliding contact between the flow rectification plates. Therefore, the side rectification plate 50 desired to be movable does not contact with the other side rectification plate 50 and the bottom rectification plate 40 even when the side rectification plate 50 is disposed at a standard position (a position where the box-shaped rectification plate is configured). However, when importance is attached to further improving the effect of restricting the air flow, the movable side flow rectification plate 50 may be brought into contact with the other side flow rectification plate 50 and the bottom flow rectification plate 40 to close the gap between these flow rectification plates.

The gas supply mechanism 60 is a mechanism for returning the inside of the chamber 10 to the atmospheric pressure at the end of the reduced-pressure drying process. As shown in fig. 1, the bottom plate portion 11 of the chamber 10 is provided with an air supply port 16 f. The air supply port 16f is located below the bottom flow rectification plate 40. The air supply mechanism 60 includes an air supply pipe 61 connected to the air supply port 16f, an air supply valve Vf, and an air supply source 62. One end of the air supply pipe 61 is connected to the air supply port 16 f. The other end of the air supply pipe 61 is connected to an air supply source 62. The air supply valve Vf is provided in the path of the air supply pipe 61.

When the gas supply valve Vf is opened, gas is supplied from the gas supply source 62 to the internal space of the chamber 10 through the gas supply pipe 61 and the gas supply port 16 f. This can increase the gas pressure in the chamber 10. The gas supplied from the gas supply source 62 may be an inert gas such as nitrogen or may be clean dry air.

The pressure gauge 70 is a sensor that measures the air pressure inside the chamber 10. As shown in fig. 1, a pressure gauge 70 is installed on a portion of the chamber 10. The pressure gauge 70 measures the air pressure in the chamber 10, and outputs the measurement result to the control unit 80.

The control unit 80 is a unit for controlling the operation of each unit of the vacuum drying apparatus 1. The control unit 80 is constituted by a computer having a processor 801 such as a CPU, a memory 802 such as a RAM, and a storage unit 803 such as a hard disk drive. The storage unit 803 stores a computer program and various data for executing the reduced pressure drying process. The control unit 80 reads a computer program and various data from the storage unit 803 into the memory 802, and the processor 801 performs an arithmetic process based on the computer program and the data to control the operation of each unit in the decompression drying device 1.

Fig. 4 is a block diagram schematically showing functions implemented in the control unit 80. As shown in fig. 4, the controller 80 is electrically connected to the shutter drive mechanism 16, the lift mechanism 23, the four independent valves Va to Vd, the main valve Ve, the vacuum pump 32, the air supply valve Vf, and the pressure gauge 70. The control unit 80 controls the operations of the above-described units with reference to the measurement value output from the pressure gauge 70.

As schematically shown in fig. 4, the control unit 80 includes a gate control unit 81, an elevation control unit 82, a switching control unit 83, an exhaust control unit 84, a pump control unit 85, and an air supply control unit 86. The shutter control unit 81 controls the operation of the shutter drive mechanism 16. The elevation control unit 82 controls the operation of the elevation mechanism 23. The switching controller 83 independently controls the open/close states of the four independent valves Va to Vd. The exhaust control unit 84 controls the open/close state and the opening degree of the main valve Ve. The pump control unit 85 controls the operation of the vacuum pump 32. The air supply control unit 86 controls the open/close state of the air supply valve Vf. The functions of these units are realized by operating the processor 801 based on the computer program and various data.

< 2 > about the vacuum drying treatment

Next, the reduced-pressure drying process of the substrate 9 using the reduced-pressure drying apparatus 1 will be described. Fig. 5 is a flowchart showing the flow of the reduced pressure drying process. Fig. 6 is a graph showing a change in the gas pressure in the chamber 10.

When the reduced-pressure drying process is performed, first, the substrate 9 is carried into the chamber 10 (step S1). An undried coating layer 90 is formed on the upper surface of the substrate 9. In step S1, first, the shutter control unit 81 operates the shutter drive mechanism 16. Thereby, the shutter 15 is moved from the closed position to the open position to open the carry-in/carry-out port 14. Then, the substrate 9 is carried into the chamber 10 through the carrying-in/out port 14 of the chamber 10 in a state where the substrate 9 is placed on the fork-shaped hand by a carrying robot, not shown.

At this time, the stage 20 is disposed at the lowered position H1. The transfer robot places the substrate 9 on the upper surface of the stage 20 with the fork-shaped hand inserted between the support plates 21 of the stage 20. When the substrate 9 is placed on the stage 20, the transfer robot retracts to the outside of the chamber 10. Then, the shutter control unit 81 operates the shutter drive mechanism 16 again to move the shutter 15 from the open position to the closed position, thereby closing the loading/unloading port 14. Thereby, the substrate 9 is accommodated in the internal space of the chamber 10.

Next, the reduced pressure drying apparatus 1 raises the stage 20 (step S2). Specifically, the elevation controller 82 operates the elevation mechanism 23 to move the stage 20 from the lowered position H1 to the raised position H2. Fig. 7 is a diagram showing a state in the chamber 10 when the stage 20 is disposed at the raised position H2. As shown in fig. 7, the upper end of the side rectifying plate 50 is lower than the height of the substrate 9 supported by the stage 20 at the raised position H2. Therefore, in step S2, the substrate 9 supported by the stage 20 is raised above the upper end of the side rectifying plate 50. The upper surface of the substrate 9 and the top surface portion 13 of the chamber 10 face each other with a slight gap therebetween.

Subsequently, the decompression drying device 1 starts decompression in the chamber 10. That is, the pump control unit 85 starts the operation of the vacuum pump 32. The switching controller 83 opens some of the independent valves Va to Vd, and the exhaust controller 84 opens the main valve Ve. Thereby, the gas starts to be discharged from the chamber 10 to the gas discharge pipe 31. The reduced-pressure drying apparatus 1 first performs a first process of gradually reducing the pressure in the internal space of the chamber 10 (step S3). In the first process, the exhaust control unit 84 adjusts the opening degree of the main valve Ve to an opening degree smaller than the second process to the fourth process, which will be described later. As a result, as shown in fig. 6 from time t1 to time t2, the pressure in the chamber 10 gradually decreases from the atmospheric pressure P0.

In step S3, the stage 20 is disposed at the raised position H2 as described above. Therefore, as indicated by the broken-line arrows in fig. 7, the gas in the chamber 10 flows from the space below the substrate 9 to the exhaust pipe 31 through the space between the side flow regulating plate 50 and the side wall portion 12, the space between the bottom flow regulating plate 40 and the bottom plate portion 11, and the exhaust ports 16a to 16 d. Therefore, the gas flow formed in the chamber 10 does not easily affect the upper surface of the substrate 9.

However, in step S3, a minute air flow is generated in the space between the upper surface of the substrate 9 and the top surface portion 13. In addition, due to the reduced pressure, the solvent starts to vaporize from the coating layer 90. Therefore, the switching controller 83 sequentially switches the open/closed states of the four independent valves Va to Vd in order to suppress the occurrence of uneven drying of the coating layer 90 due to the air flow between the upper surface of the substrate 9 and the top surface portion 13.

Fig. 8 is a timing chart showing the change in the open/close states of the four independent valves Va to Vd. As shown in fig. 8, the switching controller 83 closes one of the four independent valves Va to Vd and opens the other independent valve. Then, the switching control unit 83 sequentially changes the one independent valve to be closed. Specifically, the following states are sequentially switched: a first state (time ta) in which one independent valve Va is closed and the other three independent valves Vb, Vc, Vd are opened, a second state (time tb) in which one independent valve Vb is closed and the other three independent valves Va, Vc, Vd are opened, a third state (time tc) in which one independent valve Vc is closed and the other three independent valves Va, Vb, Vd are opened, and a fourth state (time td) in which one independent valve Vd is closed and the other three independent valves Va, Vb, Vc are opened.

By so doing, the direction of the gas flow formed in the space between the upper surface of the substrate 9 and the top surface portion 13 changes with the switching of the individual valves Va to Vd during the first process. Therefore, the coating layer 90 on the upper surface of the substrate 9 can be uniformly dried.

In particular, in the present embodiment, as shown in fig. 9, the upper surface of the substrate 9 has a coating region A3 covered with the coating layer 90 and a non-coating region a4 exposed from the coating layer 90. The solvent is vaporized from the coating region A3, but the solvent is not vaporized from the non-coating region a 4. Therefore, if the gas flow direction is constant, a difference occurs in the degree of progress of drying at the end edge portion of the coating region A3 due to the influence of the solvent vapor in the portion where the gas flows from the coating region A3 to the non-coating region a4 and the portion where the gas flows from the non-coating region a4 to the coating region A3. However, as described above, when the opening and closing states of the four independent valves Va to Vd are sequentially switched to change the airflow direction, such a difference in the degree of progress of drying can be reduced. Therefore, uneven drying of the coating layer 90 due to the solvent vapor can be suppressed.

Next, the decompression drying device 1 lowers the stage 20 (step S4). Specifically, the elevation controller 82 operates the elevation mechanism 23 to move the stage 20 from the elevation position H2 to the descent position H1. Fig. 10 is a diagram showing a state in the chamber 10 when the stage 20 is disposed at the lowered position H1. As shown in fig. 10, the upper end of the side rectifying plate 50 is higher than the height of the substrate 9 supported by the stage 20 at the lowered position H1. Therefore, in step S4, the substrate 9 supported by the stage 20 is lowered to a position below the upper end portion of the side rectification plate 50.

Next, the decompression drying device 1 performs a second process of rapidly decompressing the internal space of the chamber 10 (step S5). In the second process, the exhaust control portion 84 changes the opening degree of the main valve Ve to an opening degree larger than that in the first process. As a result, the air pressure in the chamber 10 rapidly decreases from time t2 to time t3 in fig. 6.

In the second process, as described above, the stage 20 is disposed at the lowered position H1. Therefore, as indicated by broken line arrows in fig. 10, the gas present in the space on the upper surface side of the substrate 9 flows through the space between the side flow regulating plate 50 and the side wall portion 12, the space between the bottom flow regulating plate 40 and the bottom plate portion 11, and the exhaust ports 16a to 16d, and further flows into the exhaust pipe 31. This can suppress generation of a strong airflow near the substrate 9. In particular, the concentration of the gas flow on the peripheral edge portion of the substrate 9 can be suppressed. Therefore, uneven drying of the coating layer 90 due to the airflow can be suppressed.

In addition, in this second treatment, the solvent is actively vaporized from the coating layer 90. Therefore, the switching controller 83 sequentially switches the open/closed states of the four independent valves Va to Vd in the same manner as the first process described above in order to suppress uneven drying of the coating layer 90. That is, as shown in fig. 8, the switching controller 83 closes one of the four independent valves Va to Vd and opens the other independent valve. The switching control unit 83 sequentially changes the individual valve to be closed. By so doing, the direction of the gas flow formed along the upper surface of the substrate 9 during the second process is changed in accordance with the switching of the individual valves Va to Vd. Therefore, the coating layer 90 on the upper surface of the substrate 9 can be uniformly dried.

When the air pressure in the internal space of the chamber 10 is reduced to a predetermined pressure P1, the coating layer 90 is boiled. Then, when boiling starts, as shown in fig. 6 from time t3 to t4, the pressure in the chamber 10 becomes almost constant. In this manner, the reduced-pressure drying apparatus 1 performs the third process of continuously exhausting the gas from the chamber 10 while boiling the coating layer 90 (step S6).

In this third process, vaporization of the solvent from the coating layer 90 becomes more active than the second process. Therefore, the switching controller 83 sequentially switches the open/closed states of the four independent valves Va to Vd in the same manner as the first process and the second process in order to suppress uneven drying of the coating layer 90. That is, as shown in fig. 8, the switching controller 83 closes one of the four independent valves Va to Vd and opens the other independent valve. The switching control unit 83 sequentially changes the individual valve to be closed. By so doing, the direction of the gas flow formed along the upper surface of the substrate 9 during the third process is changed in accordance with the switching of the individual valves Va to Vd. Therefore, the coating layer 90 on the upper surface of the substrate 9 can be uniformly dried.

Finally, when the solvent of the coating layer 90 is sufficiently vaporized, the boiling of the coating layer 90 ends. By so doing, the gas pressure in the chamber 10 rapidly decreases again as shown at time t4 to t5 in fig. 6. In this manner, the reduced-pressure drying apparatus 1 performs the fourth process of further reducing the pressure in the internal space of the chamber 10 after the coating layer 90 is boiled (step S7).

In the fourth process, a slight amount of the solvent remaining in the coating layer 90 is vaporized, but the vaporization of the solvent component is not active as compared with the first to third processes. Therefore, the switching controller 83 opens all of the four independent valves Va to Vd. This promotes the evacuation of the gas from the chamber 10, and the internal space of the chamber 10 is rapidly depressurized to the target pressure P2.

When the air pressure in the chamber 10 reaches the target pressure P2, the exhaust control portion 84 closes the main valve Ve. Thereby, the suction of the gas from the chamber 10 is ended and the drying of the coating layer 90 is completed.

Thereafter, the air supply controller 86 opens the air supply valve Vf. By doing so, the gas is supplied from the gas supply source 62 to the inside of the chamber 10 through the gas supply pipe 61 and the gas supply port 16f (step S8). Thereby, the air pressure in the chamber 10 rises to the atmospheric pressure P0 again. At this time, a relatively strong air flow is generated in the chamber 10, but since the coating layer 90 is sufficiently dried, uneven drying due to the air flow is less likely to occur. The gas supplied from the gas supply port 16f flows through the space between the bottom flow regulating plate 40 and the bottom plate 11 and the space between the side flow regulating plate 50 and the side wall 12, and further flows toward the inside of the chamber 10. This can suppress generation of a strong airflow near the substrate 9.

When the air pressure in the chamber 10 reaches the atmospheric pressure, the air supply control unit 86 closes the air supply valve Vf. Further, the shutter control unit 81 operates the shutter drive mechanism 16. Thereby, the shutter 15 is moved from the closed position to the open position to open the carry-in/carry-out port 14. Then, the transport robot, not shown, transports the dried substrate 9 supported by the stage 20 to the outside of the chamber 10 (step S9). In this way, the vacuum drying process of one substrate 9 is completed.

As described above, in the vacuum drying apparatus 1, the switching process of sequentially switching the open/closed states of the four independent valves Va to Vd is performed in the first to third processes. Therefore, the amounts of exhaust gas from the four exhaust ports 16a to 16d are sequentially switched during each of the first to third processes. Thereby, the direction of the airflow formed along the upper surface of the substrate 9 changes. Therefore, the coating layer 90 on the upper surface of the substrate 9 can be uniformly dried.

< 3. modification example >

While the embodiments of the present invention have been described above, the present invention is not limited to the embodiments. Hereinafter, various modifications will be described mainly focusing on differences from the above embodiment.

< 3-1. first modification

In the above embodiment, the switching process of sequentially switching the open/closed states of the four independent valves Va to Vd is performed during the first process to the third process. However, the switching process may be performed only at a partial process among the first to third processes. For example, in the third process in which the coating layer 90 is boiled, vaporization of the solvent component becomes most active. Therefore, the switching process can be performed only at the time of the third process.

< 3-2 > second modification

In the above embodiment, in the switching process, one of the four independent valves Va to Vd is closed and the other three independent valves are opened, and the closed one independent valve is sequentially changed. However, two of the four independent valves Va to Vd may be closed and the other two independent valves may be opened, and the two independent valves to be closed may be sequentially changed. Alternatively, three of the four independent valves Va to Vd may be closed and the other one may be opened, and the three valves to be closed may be sequentially changed. That is, the switching controller 83 may change the open/close state of some of the plurality of individual valves and sequentially change some of the individual valves. However, as in the above-described embodiment, it is easier to ensure the entire exhaust amount of the exhaust pipe 31 by closing the individual valves Va to Vd one by one.

< 3-3. third modification

In the above embodiment, any one of the four independent valves Va to Vd is always closed during the switching process. However, the switching process may include a time period for opening all of the four independent valves Va to Vd. In this case, the exhaust gas control portion 84 may control the opening degree of the main valve Ve in accordance with the number of the independent valves in the open state. For example, when all of the four independent valves Va to Vd are opened, the opening degree of the main valve Ve may be smaller than that when one independent valve is closed. By doing so, it is possible to suppress a change in the amount of exhaust gas in the entire exhaust pipe 31.

< 3-4. fourth modification

In the above embodiment, the four independent valves Va to Vd are sequentially closed for the same time. That is, all of the times ta, tb, tc, and td in fig. 8 are the same time. However, even during this switching process, the drying of the coating layer 90 is proceeding. Therefore, the amount of the solvent vaporized from the coating layer 90 may gradually decrease during the switching process. In view of these aspects, the times ta, tb, tc, td may be varied. Specifically, as shown in FIG. 11, the time ta, tb, tc, td can be gradually extended (ta < tb < tc < td). By doing so, the vaporization amount of the solvent in each time can be made uniform.

< 3-5 > fifth modification

In the above embodiment, the four independent valves Va to Vd are on-off valves that switch between only an open state and a closed state. However, the four independent valves Va to Vd may be opening degree control valves whose opening degrees can be adjusted. In the switching process, instead of completely closing some of the individual valves, the opening degree of some of the individual valves may be made smaller than the opening degree of the other individual valves. That is, the switching process may be a process of changing the opening degree of a part (for example, one) of the plurality of independent valves and sequentially changing the part of the independent valves. By so doing, the gas flow in the chamber 10 can be changed more gently than in the case of using the opening and closing valve.

< 3-6. sixth modification

The decompression drying device 1 of the above embodiment includes the bottom flow regulating plate 40 and the four side flow regulating plates 50 in the chamber 10. However, as shown in fig. 12, the decompression drying device 1 may not include the side rectifying plate 50. In this case as well, the length of each side of the bottom surface rectifying plate 40 is longer than the long side and the short side of the rectangular substrate 9 in plan view. Therefore, regardless of the orientation of the substrate 9 placed on the stage 20, when the pressure in the chamber 10 is reduced, as indicated by the broken-line arrows in fig. 12, the gas on the upper surface side of the substrate 9 can flow to the lower side of the bottom surface rectifying plate 40 through the side surface of the bottom surface rectifying plate 40. This can suppress the concentration of the gas flow on the peripheral edge of the substrate 9. Therefore, uneven drying of the coating layer 90 formed on the upper surface of the substrate 9 can be suppressed.

< 3-7. seventh modification

The decompression drying device 1 of the above embodiment includes the bottom flow rectification plate 40 and the four side flow rectification plates 50 in the chamber 10. However, the decompression drying device 1 may further include a top flow rectification plate 51 as shown in fig. 13 in addition to the bottom flow rectification plate 40 and the four side flow rectification plates 50. The top fairing 51 is located between the upper surface of the substrate 9 supported by the stage 20 and the lower surface of the top portion 13 of the chamber 10. In addition, the top surface flow rectification plate 51 is horizontally expanded along the lower surface of the top surface portion 13 of the chamber 10. The top flow rectification plate 51 is fixed to the top surface portion 13 of the chamber 10 via a plurality of pillars (not shown).

The top rectifying plate 51 has a plurality of openings 52 through which gas passes. By doing so, when the pressure inside the chamber 10 is reduced, the gas on the upper surface side of the substrate 9 flows into the upper side of the top surface baffle plate 51 through the plurality of openings 52. Then, as shown by the broken line arrows in fig. 13, air flows are formed that flow through the space between the top surface flow rectifying plate 51 and the top surface portion 13, the space between the side surface flow rectifying plate 50 and the side wall portion 12, and the space between the bottom surface flow rectifying plate 40 and the bottom plate portion 11, and further flow toward the exhaust ports 16a to 16 d. With this configuration, the gas can be made to flow in a space away from the substrate 9, and the gas flow formed in the vicinity of the substrate 9 can be reduced. In addition, the gas flow can be suppressed from concentrating on the peripheral edge portion of the substrate 9. Therefore, uneven drying of the coating layer 90 formed on the upper surface of the substrate 9 can be suppressed.

< 3-8. other modifications

In the above embodiment, the chamber 10 has four exhaust ports 16a to 16 d. However, the chamber 10 may have two, three, or more than five exhaust ports.

The change in the gas pressure in the chamber 10 when the reduced-pressure drying process is performed may not necessarily be the same as that in fig. 6. The decompression drying apparatus 1 can decompress the inside of the chamber 10 by steps different from the first to fourth processes.

The reduced-pressure drying apparatus 1 of the above embodiment can dry the coating layer 90 on the substrate 9 only by reducing the pressure. However, the reduced-pressure drying apparatus 1 can dry the coating layer 90 on the substrate 9 by reducing pressure and heating.

In the above embodiment, the side wall 12 of the chamber 10 is provided with the loading/unloading port 14 for the substrate 9. However, the four side walls 12 and the top surface 13 of the chamber 10 may be integrated with each other, and the lid may be configured to be spaced apart from the bottom plate 11 and to be retracted upward. In this case, the four side rectifying plates 50 may be fixed to the lid portion and move upward together with the lid portion.

The reduced-pressure drying apparatus 1 according to the above embodiment is a substrate for processing an organic EL display device. However, the decompression drying apparatus of the present invention can treat substrates for other precision electronic parts such as liquid crystal display devices and semiconductor wafers.

The elements appearing in the above embodiments and modifications may be appropriately combined within a range not inconsistent with each other.

Claims

1. A reduced-pressure drying apparatus for drying a coating layer containing a solvent formed on an upper surface of a substrate by reducing pressure,

the disclosed device is provided with:

a chamber for receiving a substrate;

a stage supporting a substrate from below inside the chamber;

a plurality of exhaust ports disposed in the chamber;

a pressure reducing mechanism that sucks the gas in the chamber through the plurality of exhaust ports; and

a control unit that controls the decompression mechanism,

the pressure reducing mechanism has a plurality of independent valves that independently adjust the amounts of exhaust gas from the plurality of exhaust ports,

the control unit executes a switching process of sequentially changing a part of the plurality of independent valves so as to change an opening/closing state or an opening degree of the independent valves at a time.

2. The reduced-pressure drying apparatus according to claim 1,

the plurality of exhaust ports are located below a substrate supported by the stage.

3. A reduced-pressure drying apparatus according to claim 1 or 2,

a plurality of the individual valves are open-close valves,

the control unit sequentially changes a part of the independent valves so that the part of the independent valves is closed and the other independent valves are opened.

4. The reduced-pressure drying apparatus according to claim 3,

the control unit sequentially changes one independent valve to close one independent valve and open the other independent valves at a time.

5. A reduced-pressure drying apparatus according to claim 1 or 2,

a plurality of the independent valves are opening degree control valves capable of adjusting opening degrees,

the control unit sequentially changes a part of the independent valves so that the opening degree of the part of the independent valves is smaller than the opening degree of the other independent valves.

6. The reduced-pressure drying apparatus according to claim 5,

the control unit sequentially changes one of the independent valves so that the opening degree of the one of the independent valves is smaller than the opening degrees of the other independent valves.

7. A reduced-pressure drying apparatus according to claim 1 or 2,

the pressure reducing mechanism includes:

a plurality of independent pipes having one end connected to the plurality of exhaust ports; and

one main pipe connected to the other ends of the plurality of independent pipes,

the independent valves are provided to the plurality of independent pipes,

the pressure reducing mechanism further includes a main valve that is provided in the main pipe and is capable of adjusting an opening degree.

8. The reduced-pressure drying apparatus according to claim 7,

the control unit controls the opening degree of the main valve in accordance with the opening/closing state or the opening degree of the plurality of independent valves.

9. A reduced-pressure drying apparatus according to claim 1 or 2,

the control section executes the switching process at least when the coating layer is boiled.

10. A reduced-pressure drying apparatus according to claim 1 or 2,

the substrate upper surface has:

a portion covered by the coating layer; and

a portion exposed from the coating layer.