JP7309294B2 - Vacuum dryer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vacuum drying apparatus for drying a coating layer formed on the upper surface of a substrate under reduced pressure.

Conventionally, in the manufacturing process of an organic EL display, a coating layer that serves as a hole injection layer, a hole transport layer, or a light emitting layer is formed on the upper surface of a substrate. The coating layer is partially applied to the upper surface of the substrate by an inkjet device. Then, the substrate on which the coating layer is formed is transported into the chamber of the reduced pressure drying device and undergoes reduced pressure drying processing. As a result, the solvent contained in the coating layer evaporates and the coating layer dries.

A vacuum drying apparatus includes a chamber for housing a substrate and a vacuum mechanism for sucking gas from the chamber. A conventional vacuum drying apparatus is described in Patent Document 1, for example.

JP 2018-49806 A

A conventional reduced-pressure drying apparatus has an exhaust port for discharging gas in the chamber provided on the bottom surface of the chamber. This is to form a uniform airflow on the upper surface side of the substrate when the pressure in the chamber is reduced. However, if there is an exhaust port on the bottom of the chamber, the gas on the upper surface side of the substrate passes through the sides of the substrate toward the exhaust port. Therefore, the airflow concentrates on the peripheral edge of the substrate. As a result, there is a difference in the progress of drying between the vicinity of the center of the substrate and the vicinity of the periphery of the substrate. As a result, uneven drying may occur in the coating layer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vacuum drying apparatus capable of uniformly drying a coating layer formed on the upper surface of a substrate.

In order to solve the above problems, a first invention of the present application is a reduced pressure drying apparatus for drying a coating layer formed on an upper surface of a substrate by reducing pressure, comprising: a chamber for accommodating the substrate; a stage supporting from below, a bottom straightening plate positioned between the substrate supported by the stage and the bottom plate of the chamber and spreading along the upper surface of the bottom plate, and a bottom straightening plate positioned below the bottom plate and a decompression mechanism for sucking gas in the chamber through the plurality of exhaust ports. is larger than the substrate, the stage has a support plate and a plurality of support pins erected on the upper surface of the support plate and in contact with the lower surface of the substrate; It is located on the lower side with a gap from

A second invention of the present application is the reduced-pressure drying apparatus according to the first invention, wherein the bottom straightening plate is square in top view, and the plurality of exhaust ports are arranged on diagonal lines of the bottom straightening plate in top view. To position.

A third invention of the present application is the vacuum drying apparatus according to the first invention or the second invention, wherein the substrate supported by the stage and the side wall of the chamber are positioned along the inner surface of the side wall. It further comprises a widening side rectifying plate.

A fourth invention of the present application is the reduced-pressure drying apparatus according to the third invention, wherein the stage is capable of moving up and down between a lowered position and a raised position higher than the lowered position, and the upper end of the side rectifying plate The portion is higher than the height of the substrate supported by the stage at the lowered position and lower than the height of the substrate supported by the stage at the raised position.

A fifth invention of the present application is the reduced-pressure drying apparatus according to the third invention or the fourth invention, wherein at least part of the side straightening plate is movable with respect to the bottom straightening plate.

A sixth invention of the present application is the reduced-pressure drying apparatus according to the fifth invention, wherein the bottom straightening plate and the side straightening plate movable with respect to the bottom straightening plate are not in contact with each other.

A seventh invention of the present application is the vacuum drying apparatus according to any one of the third invention to the sixth invention, wherein the vacuum drying apparatus is positioned between the substrate supported by the stage and the top plate portion of the chamber, A top straightening plate extending along the lower surface of the top plate portion is further provided, and the top straightening plate has an opening for passing gas.

According to the first to seventh inventions of the present application, when the pressure in the chamber is reduced, the gas on the upper surface side of the substrate flows below the bottom straightening plate through the sides of the bottom straightening plate. As a result, it is possible to suppress concentration of the airflow on the peripheral portion of the substrate. In addition, regardless of the orientation of the substrate, the bottom current plate is larger than the substrate when viewed from above. Therefore, it is possible to suppress the change in the gas flow during depressurization depending on the orientation of the substrate supported by the stage. Therefore, the coating layer formed on the upper surface of the substrate can be dried uniformly.

In particular, according to the second invention of the present application, a more uniform airflow can be formed when the pressure inside the chamber is reduced.

In particular, according to the third invention of the present application, when the pressure in the chamber is reduced, the gas on the upper surface side of the substrate flows through the outside of the side rectifying plate and below the bottom rectifying plate. As a result, it is possible to further suppress concentration of the airflow on the peripheral portion of the substrate.

In particular, according to the fourth invention of the present application, when the stage is at the lowered position, an airflow can be formed from the upper surface side of the substrate toward the exhaust port through the outside of the side straightening plate and the lower side of the bottom straightening plate. Thereby, a uniform airflow can be formed along the upper surface of the substrate. On the other hand, when the stage is at the raised position, an air flow can be formed from the lower surface side of the substrate toward the exhaust port through the outside of the side straightening plate and the lower side of the bottom straightening plate. Thereby, it is possible to suppress the formation of an air flow on the upper surface side of the substrate.

In particular, according to the fifth invention of the present application, by making at least a part of the side rectifying plate movable, it is possible to secure a path for loading and unloading the substrate.

In particular, according to the sixth invention of the present application, it is possible to suppress generation of dust due to sliding contact between the bottom straightening plate and the side straightening plate.

In particular, according to the seventh invention of the present application, an airflow can be formed from the upper surface side of the substrate toward the exhaust port through the upper side of the top plate, the outside of the side plate, and the lower side of the bottom plate.

It is a longitudinal cross-sectional view of a reduced-pressure drying device. It is a cross-sectional view of a reduced-pressure drying device. It is a perspective view of a board|substrate. 3 is a block diagram conceptually showing functions implemented in a control unit; FIG. 4 is a flow chart showing the flow of a reduced pressure drying process; 4 is a graph showing changes in air pressure within the chamber; FIG. 10 is a diagram showing the state inside the chamber when the stage is placed at the raised position; 4 is a timing chart showing changes in the open/closed states of four individual valves; 4 is a partial vertical cross-sectional view of the substrate; FIG. FIG. 10 is a diagram showing the state inside the chamber when the stage is placed at the lowered position; It is a timing chart showing changes in the open/closed state of four individual valves according to a modification. It is a longitudinal cross-sectional view of a reduced-pressure drying apparatus according to a modification. It is a longitudinal cross-sectional view of a reduced-pressure drying apparatus according to a modification.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. Regarding the configuration of the vacuum drying device>
FIG. 1 is a longitudinal sectional view of a reduced pressure drying apparatus 1 according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of the reduced pressure drying apparatus 1. As shown in FIG. This reduced-pressure drying apparatus 1 is an apparatus for performing a reduced-pressure drying process on a substrate 9 in the manufacturing process of an organic EL display. A rectangular glass substrate is used for the substrate 9 . A coating layer 90 (see FIG. 9) containing an organic material and a solvent is partially formed in advance on the upper surface of the substrate 9 . The coating layer 90 becomes a hole injection layer, a hole transport layer, or a light emitting layer of the organic EL display by being dried by the reduced pressure drying device 1 .

FIG. 3 is a perspective view of the substrate 9. FIG. The substrate 9 has a rectangular shape with different lengths and widths when viewed from above. As shown in FIG. 2, on the upper surface of the substrate 9, a plurality of circuit areas A1 forming a circuit pattern of the organic EL display are arranged. In the example of FIG. 2, four rectangular circuit areas A1 are arranged on the upper surface of the substrate 9 in a matrix of two rows and two columns. However, the shape, number, and arrangement of the circuit area A1 are not limited to this example. The coating layer 90 is formed according to a circuit pattern in each circuit region A1 by an inkjet device in a coating process prior to the reduced pressure drying process. Therefore, each circuit area A1 has a portion covered with the coating layer 90 and a portion exposed from the coating layer 90. FIG. A boundary area A2 between the adjacent circuit areas A1 is a portion exposed from the coating layer 90. As shown in FIG.

As shown in FIGS. 1 and 2, the vacuum drying apparatus 1 includes a chamber 10, a stage 20, a decompression mechanism 30, a bottom straightening plate 40, a side straightening plate 50, an air supply mechanism 60, a pressure gauge 70, and a controller 80. I have.

The chamber 10 is a pressure-resistant container having an internal space in which the substrate 9 is accommodated. The chamber 10 is fixed on an apparatus frame (not shown). The shape of the chamber 10 is a flat rectangular parallelepiped. The chamber 10 has a substantially square bottom plate portion 11 , four side wall portions 12 , and a substantially square top surface portion 13 . The four side wall portions 12 vertically connect the four edge sides of the bottom plate portion 11 and the four edge sides of the top surface portion 13 .

One of the four side walls 12 is provided with a loading/unloading port 14 and a shutter 15 for opening and closing the loading/unloading port 14 . The shutter 15 is connected to a shutter drive mechanism 16 composed of an air cylinder or the like. When the shutter drive mechanism 16 is operated, the shutter 16 moves between a closed position that closes the loading/unloading port 14 and an open position that opens the loading/unloading port 14 . With the shutter 16 placed in the closed position, the interior space of the chamber 10 is sealed. With the shutter 16 at the open position, the substrate 9 can be loaded into the chamber 10 and unloaded from the chamber 10 through the loading/unloading port 14 .

The stage 20 is a support that supports the substrate 9 inside the chamber 10 . The stage 20 has multiple support plates 21 . The plurality of support plates 21 are arranged at intervals in the horizontal direction. A plurality of support pins 22 are erected on the upper surface of each plate 21 . The substrate 9 is arranged on top of the plurality of plates 21 . The substrate 9 is supported in a horizontal posture by contacting the lower surface of the substrate 9 with the upper ends of the plurality of support pins 22 .

A 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 conceptually shown in FIG. When the lifting mechanism 23 is operated, the stage 20 moves between a lowered position H1 (the position indicated by the solid line in FIG. 1) and an elevated position H2 (the position indicated by the two-dot chain line in FIG. 1) higher than the lowered position H1. move up and down between them. At this time, the plurality of plates 21 moves up and down as a unit.

The decompression mechanism 30 is a mechanism that reduces the pressure inside the chamber 10 by sucking gas from the internal space of the chamber 10 . As shown in FIGS. 1 and 2, the bottom plate portion 11 of the chamber 10 is provided with four exhaust ports 16a to 16d. The four exhaust ports 16a to 16d are located below the substrate 9 supported by the stage 20 and below the bottom straightening plate 40, which will be described later. The decompression mechanism 30 has an exhaust pipe 31 connected to the four exhaust ports 16a-16d, four individual valves Va-Vd, a main valve Ve, and a vacuum pump 32.

The exhaust pipe 31 has four individual pipes 31a to 31d and one main pipe 31e. One ends of the four individual pipes 31a-31d are connected to the four exhaust ports 16a-16d, respectively. The other ends of the four individual pipes 31a merge into one and are connected to one end of the main pipe 31e. The other end of the main pipe 31 e is connected to the vacuum pump 32 . The four individual valves Va to Vd are respectively provided on the routes of the four individual pipes 31a. The main valve Ve is provided on the route of the main pipe 31e.

With the loading/unloading port 14 closed by the shutter 15, at least a portion of the four individual valves Va to Vd and one main valve Ve are opened, and the vacuum pump 32 is operated. It is discharged to the outside of the chamber 10 through the exhaust pipe 31 . Thereby, the pressure in the internal space of the chamber 10 can be lowered.

The four individual valves Va-Vd are valves for individually adjusting the exhaust amounts from the four exhaust ports 16a-16d. The individual valves Va to Vd of this embodiment are open/close valves that switch between an open state and a closed state based on commands from the control unit 80 . The main valve Ve is a valve for adjusting the total exhaust amount from the four exhaust ports 16a-16d. The main valve Ve of this embodiment is an opening degree control valve that can adjust the degree of opening based on a command from the control unit 80 .

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

The bottom straightening plate 40 is a plate for regulating the flow of gas when the pressure inside the chamber 10 is reduced. The bottom plate 40 is positioned between the substrate 9 supported by the stage 20 and the bottom plate portion 11 of the chamber 10 . More specifically, the bottom straightening plate 40 is positioned below the stage 20 at the lowered position H1 with a space therebetween and above the upper surface of the bottom plate portion 11 with a space therebetween. Further, the bottom straightening plate 40 extends horizontally along the top surface of the bottom plate portion 11 . The bottom straightening plate 40 is fixed to the bottom plate portion 11 of the chamber 10 via a plurality of supports (not shown).

As shown in FIG. 2, the shape of the bottom straightening plate 40 is square when viewed from above. The length of each side of the bottom rectifying plate 40 when viewed from above is longer than both the long side and the short side of the rectangular substrate 9 . Therefore, regardless of the orientation of the substrate 9 placed on the stage 20 , the bottom rectifying plate 40 is larger than the substrate 9 when viewed from above.

The side rectifying plate 50 is a plate for regulating the flow of gas when the pressure inside the chamber 10 is reduced, along with the bottom rectifying plate 40 . The side straightening plate 50 is positioned 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 current plate 50 is positioned outside with a gap from the end of the substrate 9 supported by the stage 20 at the lowered position H1 and inside with a gap from the inner surface of the side wall 12 . . In this embodiment, four side rectifying plates 50 are arranged around the substrate 9 supported by the stage 20 . Each side current plate 50 extends along the inner surface of the side wall portion 12 . Therefore, the four side straightening vanes 50 form a rectangular tubular straightening vane surrounding the substrate 9 as a whole. The bottom straightening plate 40 and the four side straightening plates 50 as a whole form a bottomed cylindrical box-shaped straightening plate.

When the internal space of the chamber 10 is depressurized, the gas in the chamber 10 flows through the space between the side straightening plate 50 and the side wall portion 12, the space between the bottom straightening plate 40 and the bottom plate portion 11, and the exhaust ports 16a to 16a. It is discharged to the outside of the chamber 10 through 16d. In this way, the gas flows through the space separated from the substrate 9, so that the airflow formed near the substrate 9 can be reduced. In particular, it is possible to suppress the concentration of the airflow at the peripheral portion of the substrate 9 . 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 straightening plate formed by the bottom straightening plate 40 and the four side straightening plates 50 has a square shape when viewed from above. The length of each side of the box-shaped straightening plate when viewed from above is longer than both the long side and the short side of the rectangular substrate 9 . Therefore, regardless of the orientation of the substrate 9 placed on the stage 20, the gas flow in the chamber 10 can be made uniform when the pressure is reduced. That is, it is possible to prevent the gas flow in the chamber 10 from changing depending on the orientation of the substrate 9 .

Further, as shown in FIG. 2, the four exhaust ports 16a to 16d are all positioned on the diagonal line 41 of the square-shaped bottom straightening plate 40 when viewed from above. In this way, the exhaust ports 16a to 16d can form airflows symmetrical with respect to the center of the bottom straightening plate 40 (the intersection of the two diagonal lines 41). Thereby, a more uniform airflow can be formed inside the chamber 10 .

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

However, if the movable side straightening plate 50 contacts another side straightening plate 50 or the bottom straightening plate 50, dust may be generated due to the sliding contact between the straightening plates. Therefore, even when the movable side rectifying plate 50 is placed at the regular position (the position constituting the box-shaped rectifying plate described above), it is out of contact with the other side rectifying plates 50 and the bottom rectifying plate 40. is desirable. However, when emphasis is placed on further enhancing the effect of regulating the airflow, the movable side straightening plate 50, the other side straightening plate 50 and the bottom straightening plate 40 are brought into contact with each other, and these straightening plates are You can close the gap between

The air supply mechanism 60 is a mechanism for returning the inside of the chamber 10 to 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 16f. The air supply port 16f is located below the bottom straightening plate 40. As shown in FIG. The air supply mechanism 60 has an air supply pipe 61 connected to the air supply port 16 e , 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 16f. The other end of the air supply pipe 61 is connected to an air supply source 62 . The air supply valve Vf is provided on the route of the air supply pipe 61 .

When the air supply valve Vf is opened, gas is supplied from the air supply source 62 to the internal space of the chamber 10 through the air supply pipe 61 and the air supply port 16f. Thereby, the air pressure in the chamber 10 can be increased. The gas supplied from the air supply source 62 may be inert gas such as nitrogen gas, 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, pressure gauge 70 is attached to a portion of chamber 10 . The pressure gauge 70 measures the air pressure inside the chamber 10 and outputs the measurement result to the controller 70 .

The control section 80 is a unit for controlling the operation of each section of the reduced pressure drying apparatus 1 . The control unit 80 is configured 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 to the memory 802, and the processor 801 performs arithmetic processing according to the computer program and data, thereby controlling the operation of each unit in the reduced pressure drying apparatus 1.

FIG. 4 is a block diagram conceptually showing the functions implemented in the control unit 80. As shown in FIG. As shown in FIG. 4, the control unit 80 includes the shutter driving mechanism 16, the lifting mechanism 23, the four individual valves Va to Vd, the main valve Ve, the vacuum pump 32, the air supply valve Vf, the pressure gauge 70, and an electric properly connected. The control unit 80 controls the operation of each unit while referring to the measured value output from the pressure gauge 70 .

As conceptually shown in FIG. 4 , the control section 80 has a shutter control section 81 , an elevation control section 82 , a switching control section 83 , an exhaust control section 84 , a pump control section 85 and an air supply control section 86 . The shutter control section 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 control unit 83 individually controls the open/closed states of the four individual valves Va to Vd. The exhaust control unit 84 controls the opening/closing state and opening degree of the main valve Ve. A pump control unit 85 controls the operation of the vacuum pump 32 . The air supply control unit 86 controls the opening/closing state of the air supply valve Vf. The functions of these units are implemented by the processor 801 operating based on the computer program and various data described above.

<2. Regarding reduced pressure 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 flow chart showing the flow of the reduced pressure drying process. FIG. 6 is a graph showing changes in air pressure inside the chamber 10. As shown in FIG.

When performing the reduced-pressure drying process, 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 S<b>1 , first, the shutter control section 81 operates the shutter drive mechanism 16 . As a result, the shutter 15 is moved from the closed position to the open position to open the loading/unloading port 14 . A transfer robot (not shown) loads the substrate 9 into the chamber 10 through the loading/unloading port 14 of the chamber 10 while placing the substrate 9 on a fork-shaped hand.

At this point, the stage 20 is located at the lowered position H1. The transport robot places the substrate 9 on the upper surface of the stage 20 while inserting a fork-shaped hand between the plates 21 of the stage 20 . After the substrate 9 is placed on the stage 20 , the transfer robot retreats 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 control unit 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 the state inside the chamber 10 when the stage 20 is arranged at the elevated position H2. As shown in FIG. 7, the upper end of the side current plate 50 is lower than the height of the substrate 9 supported by the stage 20 at the raised position H2. Therefore, in step S<b>2 , the substrate 9 supported by the stage 20 rises to a position above the upper end of the side current plate 50 . The upper surface of the substrate 9 faces the top surface portion 13 of the chamber 10 with a slight gap therebetween.

Subsequently, the pressure reduction inside the chamber 10 is started. That is, the pump control unit 85 starts operating the vacuum pump 32 . Further, the switching control unit 83 opens some of the individual valves Va to Vd, and the exhaust control unit 84 opens the main valve Ve. As a result, gas starts to be discharged from the chamber 10 to the exhaust pipe 16 . The reduced-pressure drying apparatus 1 first performs a first process of gently reducing the pressure in the internal space of the chamber 10 (step S3). In this first process, the exhaust control unit 84 adjusts the degree of opening of the main valve Ve to a smaller degree of opening than in the second to fourth processes described later. As a result, the air pressure inside the chamber 10 gradually decreases from the atmospheric pressure P0, as shown in FIG. 6 from time t1 to time t2.

In step S3, as described above, the stage 20 is placed at the raised position H2. Therefore, the gas in the chamber 10 flows from the space below the substrate 9 to the space between the side straightening plate 50 and the side wall portion 12, the bottom straightening plate 40 and the bottom plate portion 11, as indicated by the dashed arrows in FIG. and through the exhaust ports 16a to 16d to the exhaust pipe 61. Therefore, the airflow formed inside the chamber 10 does not easily affect the upper surface of the substrate 9 .

However, even in this step S3, a slight airflow is generated in the space between the upper surface of the substrate 9 and the top surface portion 13. As shown in FIG. Also, the evaporation of the solvent from the coating layer 90 has started due to the reduced pressure. Therefore, the switching control unit 83 controls the opening/closing states of the four individual valves Va to Vd in order to suppress uneven drying of the coating layer 90 due to the airflow between the upper surface of the substrate 9 and the top surface portion 13. Switch sequentially.

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

By doing so, the direction of the airflow formed in the space between the upper surface of the substrate 9 and the top surface portion 13 changes according to 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 dried uniformly.

In particular, in this embodiment, as shown in FIG. 9, the upper surface of the substrate 9 has a coating area A3 covered with the coating layer 90 and a non-coating area A4 exposed from the coating layer 90. FIG. While the solvent evaporates from the coated area A3, the solvent does not evaporate from the non-coated area A4. Therefore, assuming that the direction of the airflow is constant, the portion where the gas flows from the coating region A3 toward the non-coating region A4 and the portion where the gas flows from the non-coating region A4 toward the coating region A3 Due to the influence of the vapor of the solvent, a difference occurs in the degree of progress of drying at the edges of the coating area A3. However, as described above, by sequentially switching the opening/closing states of the four individual valves Va to Vd to change the direction of the airflow, such a difference in the progress of drying can be reduced. Therefore, uneven drying of the coating layer 90 caused by solvent vapor can be suppressed.

Next, the reduced-pressure drying apparatus 1 lowers the stage 20 (step S4). Specifically, the elevation control unit 82 operates the elevation mechanism 23 to move the stage 20 from the elevated position H2 to the lowered position H1. FIG. 10 is a diagram showing the state inside the chamber 10 when the stage 20 is arranged at the lowered position H1. As shown in FIG. 10, the upper end of the side current plate 50 is higher than the height of the substrate 9 supported by the stage 20 at the lowered position H1. Therefore, in step S<b>4 , the substrate 9 supported by the stage 20 descends to a position below the upper end of the side current plate 50 .

Subsequently, the reduced-pressure drying apparatus 1 performs a second process of rapidly reducing the pressure in the internal space of the chamber 10 (step S5). In this second process, the exhaust control unit 84 changes the opening of the main valve Ve to a larger opening than in the first process. As a result, the air pressure inside the chamber 10 rapidly drops, as shown at times t2 to t3 in FIG.

In the second process, as described above, the stage 20 is placed at the lowered position H1. Therefore, the gas existing in the space on the upper surface side of the substrate 9 flows into the space between the side straightening plate 50 and the side wall portion 12 and between the bottom straightening plate 40 and the bottom plate portion 11 as indicated by the dashed arrows in FIG. It flows to the exhaust pipe 61 through the interspace and the exhaust ports 16a-16d. Thereby, generation of a strong air current in the vicinity of the substrate 9 can be suppressed. In particular, it is possible to suppress the concentration of the airflow at the peripheral portion of the substrate 9 . Therefore, uneven drying of the coating layer 90 due to air currents can be suppressed.

Also, in this second process, the solvent is actively vaporized from the coating layer 90 . Therefore, in order to suppress uneven drying of the coating layer 90, the switching control unit 83 sequentially switches the opening/closing states of the four individual valves Va to Vd, as in the first process described above. That is, as shown in FIG. 8, the switching control unit 83 closes one of the four individual valves Va to Vd and opens the other individual valves. Then, the switching control unit 83 sequentially changes one individual valve to be closed. By doing so, the direction of the airflow formed along the upper surface of the substrate 9 changes according to the switching of the individual valves Va to Vd during the second process. Therefore, the coating layer 90 on the upper surface of the substrate 9 can be dried uniformly.

When the pressure inside the chamber 10 drops to a predetermined pressure P1, the coating layer 90 boils. Then, when boiling starts, the air pressure inside the chamber 10 becomes almost constant, as shown from time t3 to t4 in FIG. In this way, the reduced-pressure drying apparatus 1 performs the third process of continuing to evacuate the chamber 10 while boiling the coating layer 90 (step S6).

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

Eventually, when the solvent component of the coating layer 90 is sufficiently vaporized, boiling of the coating layer 90 ends. As a result, the air pressure inside the chamber 10 rapidly drops again, as shown at times t4 to t5 in FIG. Thus, the reduced-pressure drying apparatus 1 performs the fourth process of further reducing the pressure in the internal space of the chamber 10 after boiling the coating layer 90 (step S7).

Although a small amount of the solvent component remaining in the coating layer 90 evaporates in the fourth process, the solvent component evaporates less vigorously than in the first to third processes described above. Therefore, the switching control unit 83 opens all four individual valves Va to Vd. This facilitates exhaustion from the chamber 10 and rapidly decompresses the internal space of the chamber 10 to the target pressure P2.

When the air pressure inside the chamber 10 reaches the target pressure P2, the exhaust control section 84 closes the main valve Ve. This completes the suction of the gas from the chamber 10 and completes the drying of the coating layer 90 .

After that, the air supply control unit 86 opens the air supply valve Vf. Then, gas is supplied from the air supply source 62 into the chamber 10 through the air supply pipe 61 and the air supply port 16f (step S8). As a result, the pressure inside the chamber 10 rises again to the atmospheric pressure P0. At this time, a relatively strong air current is generated in the chamber 10, but since the coating layer 90 has been sufficiently dried, uneven drying caused by the air current is less likely to occur. Also, the gas supplied from the air supply port 16f flows inside the chamber 10 through between the bottom straightening plate 40 and the bottom plate portion 11 and between the side straightening plate 50 and the side wall portion 12 . Thereby, generation of a strong air current in the vicinity of the substrate 9 can be suppressed.

When the air pressure inside the chamber 10 reaches the atmospheric pressure, the air supply controller 86 closes the air supply valve Vf. Then, the shutter control section 81 operates the shutter drive mechanism 16 . As a result, the shutter 15 is moved from the closed position to the open position to open the loading/unloading port 14 . Then, a transfer robot (not shown) carries out the dried substrate 9 supported by the stage 20 to the outside of the chamber 10 (step S9). With the above, the reduced-pressure drying process for one substrate 9 is completed.

As described above, in the reduced pressure drying apparatus 1, in the first to third processes, the switching process for sequentially switching the open/closed states of the four individual valves Va to Vd is performed. Therefore, the exhaust amount from the four exhaust ports 16a to 16d is switched in sequence between the first to third processes. This changes the direction of the airflow formed along the upper surface of the substrate 9 . Therefore, the coating layer 90 on the upper surface of the substrate 9 can be dried uniformly.

<3. Variation>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Various modifications will be described below, focusing on differences from the above embodiment.

<3-1. First modification>
In the above embodiment, the switching process of sequentially switching the four individual valves Va to Vd was performed between the first process to the third process. However, the switching process may be performed only during some of the first to third processes. For example, during the third treatment in which the coating layer 90 is boiled, the solvent component is most actively evaporated. Therefore, the switching process may be performed only during the third process.

<3-2. Second modification>
In the above embodiment, in the switching process, one of the four individual valves Va to Vd is closed, the other three individual valves are opened, and the closed individual valve is sequentially changed. was However, of the four individual valves Va to Vd, two individual valves may be closed, the other two individual valves may be opened, and the closed two individual valves may be sequentially changed. Alternatively, among the four individual valves Va to Vd, three individual valves may be closed and another individual valve may be opened, and the closed three individual valves may be sequentially changed. That is, the switching control unit 83 may change the opening/closing state of some individual valves among the plurality of individual valves, and sequentially change the partial individual valves. However, closing the individual valves Va to Vd one by one as in the above embodiment makes it easier to secure the exhaust amount of the exhaust pipe 61 as a whole.

<3-3. Third modification>
In the above embodiment, one of the four individual valves Va-Vd was always closed during the switching process. However, the switching process may include time to open all four individual valves Va to Vd. In that case, the exhaust control unit 84 may control the opening degree of the main valve Ve according to the number of individual valves in the open state. For example, when all four individual valves Va to Vd are opened, the degree of opening of the main valve Ve may be made smaller than when one individual valve is closed. By doing so, it is possible to suppress the change in the exhaust amount of the exhaust pipe 61 as a whole.

<3-4. Fourth modification>
In the above embodiment, the four individual valves Va-Vd were closed sequentially for the same amount of time. That is, the times ta, tb, tc, and td in FIG. 8 were all the same time. However, drying of the coating layer 90 progresses even during this switching process. Therefore, the amount of solvent vaporized from the coating layer 90 may gradually decrease during the switching process. Considering this point, the times ta, tb, tc, and td may be varied. Specifically, as shown in FIG. 11, the times ta, tb, tc, and td may be gradually increased (ta<tb<tc<td). In this way, the amount of vaporization of the solvent can be made uniform at each time.

<3-5. Fifth modification>
In the above embodiment, the four individual valves Va to Vd are open/close valves that only switch between the open state and the closed state. However, the four individual valves Va to Vd may be opening degree control valves with adjustable opening degrees. Then, in the switching process, instead of completely closing some of the individual valves, the degree of opening of some of the individual valves may be made smaller than the degree of opening of other individual valves. That is, the switching process may be a process of changing the opening degree of some (for example, one) of the plurality of individual valves and sequentially changing the part of the individual valves. By doing so, the airflow in the chamber 10 can be changed more gently than when using an on-off valve.

<3-6. Sixth modification>
The reduced-pressure drying apparatus 1 of the above embodiment includes the bottom straightening plate 40 and the four side straightening plates 50 in the chamber 10 . However, as shown in FIG. 12, the reduced-pressure drying apparatus 1 does not have to include the side rectifying plate 50 . Even in this case, the length of each side of the bottom rectifying plate 40 when viewed from above is longer than both the long side and the short side of the rectangular substrate 9 . Therefore, regardless of the orientation of the substrate 9 placed on the stage 20, when the pressure in the chamber 10 is reduced, the gas on the upper surface side of the substrate 9 is directed to the side of the side rectifying plate 40 as indicated by the dashed arrow in FIG. through the bottom straightening plate 40 . As a result, it is possible to prevent the air current from concentrating on the peripheral 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.

<3-7. Seventh modification>
The reduced-pressure drying apparatus 1 of the above embodiment includes the bottom straightening plate 40 and the four side straightening plates 50 in the chamber 10 . However, the reduced-pressure drying apparatus 1 may include a top straightening plate 51 as shown in FIG. 13 in addition to the bottom straightening plate 40 and the four side straightening plates 50 . The top straightening plate 51 is positioned between the top surface of the substrate 9 supported by the stage 20 and the bottom surface of the top plate portion 13 of the chamber 10 . Also, the top plate 51 extends horizontally along the bottom surface of the top plate portion 13 of the chamber 10 . The top straightening plate 51 is fixed to the top plate portion 13 of the chamber 10 via a plurality of struts (not shown).

The top straightening plate 51 has a plurality of openings 52 through which gas passes. In this way, when the pressure inside the chamber 10 is reduced, the gas on the upper surface side of the substrate 9 flows through the plurality of openings 52 and flows above the top surface straightening plate 51 . 13, the space between the top straightening plate 51 and the top plate portion 13, the space between the side straightening plate 50 and the side wall portion 12, and the bottom straightening plate 40 and the bottom plate portion 11 Airflow is formed through the space between and toward the exhaust ports 16a to 16d. Even with such a configuration, the gas flows in the space apart from the substrate 9, so that the airflow formed in the vicinity of the substrate 9 can be reduced. In addition, it is possible to suppress concentration of the airflow at the peripheral 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 had four exhaust ports 16a-16d. However, the chamber 10 may have two, three, five or more outlets.

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

In the above embodiment, the side wall portion 12 of the chamber 10 is provided with the loading/unloading port 14 for the substrate 9 . However, the structure may be such that the four side wall portions 12 and the top plate portion 13 of the chamber 10 constitute an integrated lid portion, and the lid portion can be separated from the bottom plate portion 11 and retracted upward. In this case, the four side rectifying plates 50 may be fixed to the lid portion and movable upward together with the lid portion.

Further, the reduced-pressure drying apparatus 1 of the embodiment described above is for processing a substrate for an organic EL display. However, the vacuum drying apparatus of the present invention may also be used to process substrates for other precision electronic components such as liquid crystal displays and semiconductor wafers.

Also, the elements appearing in the above embodiments and modified examples may be appropriately combined within a range that does not cause contradiction.

Reference Signs List 1 vacuum drying apparatus 9 substrate 10 chamber 11 bottom plate portion 12 side wall portion 13 top plate portion 16a exhaust port 16b exhaust port 16c exhaust port 16d exhaust port 16f air supply port 20 stage 21 support plate 22 support pin 23 lifting mechanism 30 decompression mechanism 31 exhaust Piping 32 Vacuum pump 40 Bottom straightening plate 50 Side straightening plate 51 Top straightening plate 60 Air supply mechanism 61 Air supply pipe 70 Air pressure sensor 80 Control unit 90 Coating layer Va Individual valve Vb Individual valve Vc Individual valve Vd Individual valve Ve Main valve Vf air supply valve

Claims (7)

A reduced pressure drying apparatus for drying a coating layer formed on the upper surface of a substrate by reducing pressure,
a chamber containing a substrate;
a stage that supports the substrate from below inside the chamber;
a bottom straightening plate located between the substrate supported by the stage and the bottom plate of the chamber and extending along the top surface of the bottom plate;
a plurality of exhaust ports positioned below the bottom straightening plate;
a decompression mechanism for sucking gas in the chamber through the plurality of exhaust ports;
with
Regardless of the orientation of the substrate supported by the stage, the bottom rectifying plate is larger than the substrate when viewed from above,
The stage is
a support plate;
a plurality of support pins erected on the upper surface of the support plate and in contact with the lower surface of the substrate;
has
The vacuum drying apparatus , wherein the bottom straightening plate is positioned below the support plate with a space therebetween . The vacuum drying apparatus according to claim 1,
The bottom straightening plate is square in top view,
The reduced-pressure drying apparatus, wherein the plurality of exhaust ports are positioned on a diagonal line of the bottom straightening plate when viewed from above. The vacuum drying apparatus according to claim 1 or claim 2,
The reduced-pressure drying apparatus further includes a side straightening plate located between the substrate supported by the stage and the side wall of the chamber and extending along the inner surface of the side wall. The vacuum drying apparatus according to claim 3,
the stage is capable of moving up and down between a lowered position and a raised position higher than the lowered position;
The vacuum drying apparatus, wherein the upper end portion of the side rectifying plate is higher than the height of the substrate supported by the stage at the lowered position and lower than the height of the substrate supported by the stage at the raised position. The vacuum drying apparatus according to claim 3 or claim 4,
The reduced-pressure drying apparatus, wherein at least part of the side flow straightening plate is movable with respect to the bottom straightening plate. The vacuum drying apparatus according to claim 5,
The reduced-pressure drying apparatus, wherein the bottom straightening plate and the side straightening plate movable with respect to the bottom straightening plate are not in contact with each other. The vacuum drying apparatus according to any one of claims 3 to 6,
further comprising a top straightening plate positioned between the substrate supported by the stage and the top plate of the chamber and extending along the lower surface of the top plate;
The vacuum drying device, wherein the top straightening plate has an opening through which gas passes.

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