JP7637660B2 - Reduced pressure drying apparatus and reduced pressure drying method - Google Patents

Description

This disclosure relates to a reduced pressure drying device and a reduced pressure drying method.

Conventionally, reduced pressure drying apparatuses that reduce pressure and dry coating films such as photoresist applied to various substrates are known. The various substrates include, for example, glass substrates for forming various devices, ceramic substrates, semiconductor wafers, electronic device substrates, and printing plates for printing. The various devices include, for example, semiconductor devices, display panels, solar cell panels, magnetic disks, and optical disks. The display panels include, for example, liquid crystal display panels, organic electroluminescence (EL) display panels, plasma display panels, and field emission displays.

When drying a coating film using a reduced pressure drying device, for example, with multiple pins supporting a substrate inside the chamber, a vacuum pump evacuates the chamber through an exhaust port at the bottom of the chamber. This exhaust reduces the pressure inside the chamber. When the pressure inside the chamber decreases, the solvent in the coating film evaporates, allowing the coating film to dry. Then, for example, when the degree of vacuum reaches a predetermined value, exhaust from the chamber is stopped and gas is supplied into the chamber to return the pressure inside the chamber to atmospheric pressure. For example, an inert gas such as nitrogen gas or air is used as the gas.

However, in a reduced pressure drying apparatus, if the pressure inside the chamber is suddenly reduced at the beginning of the decompression process, bumping may occur in the coating film on the substrate. If bumping occurs, for example, the thickness of the coating film may vary.

The reduced pressure drying apparatus described in Patent Document 1 is able to suppress the occurrence of such bumping. The reduced pressure drying apparatus described in Patent Document 1 is provided with a lifting section that raises and lowers the support pins that support the substrate. The lifting section raises the support pins at the beginning of the decompression, thereby narrowing the gap between the substrate and the ceiling surface of the chamber. This reduces the rate at which the pressure between the substrate and the ceiling surface drops, making it possible to suppress the occurrence of bumping.

JP 2022-086766 A

However, when the distance between the substrate and the ceiling surface becomes narrow, the solvent vapor from the coating film on the substrate becomes trapped in the space between the substrate and the ceiling surface. In particular, the solvent vapor from near the center of the coating film is prone to stagnation. That is, although the solvent vapor from near the periphery of the coating film can flow outward in the horizontal direction due to concentration diffusion, it remains trapped near the center of the coating film because the concentration gradient is small near the center. For this reason, the solvent in the coating film is more likely to evaporate in the periphery than in the center. In other words, this leads to uneven drying of the coating film. Uneven drying can cause problems, such as variations in the thickness of the dried coating film.

In order to solve the above problem, the inventor has been studying a technique for cooling the ceiling surface to form a cooling surface. According to this technique, the liquid solvent condensed on the cooling surface can suppress the above uneven drying. On the other hand, the inventor has found a new problem that if the ceiling surface is simply made into a cooling surface, the liquid solvent may accumulate excessively on the cooling surface. In particular, in industrial applications, it is usually necessary to repeatedly operate the reduced pressure drying device without a long interval, and as a result, the liquid solvent is likely to accumulate excessively on the cooling surface as the operation is repeated, even if the amount of accumulation is at least in one operation. Excessively accumulated liquid solvent may have a negative effect on the implementation of reduced pressure drying. For example, if it falls on a substrate, the quality of the product using the substrate is impaired. Excessively accumulated liquid solvent can be removed by sufficiently extending the drying time under reduced pressure, but this is likely to lead to an excessive decrease in productivity.

This disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that prevents excessive accumulation of liquid solvent on the cooling surface of the cooling section while avoiding an excessive decrease in productivity.

The first aspect is a reduced pressure drying device that dries a coating film applied to the upper surface of a substrate, and includes a chamber that accommodates the substrate, a support that supports the substrate within the chamber, a cooling unit that cools a cooling surface that faces the upper surface of the substrate supported by the support, a reduced pressure mechanism that sucks gas from the chamber to reduce the pressure within the chamber, an air supply mechanism that supplies gas into the chamber to increase the pressure within the chamber, and a control unit that controls the air supply mechanism to supply a predetermined amount of gas from the air supply mechanism into the chamber in a reduced pressure state, and then supply an amount of gas from the air supply mechanism such that the pressure within the chamber becomes atmospheric pressure.

The second aspect is a reduced pressure drying apparatus according to the first aspect, in which the air supply mechanism includes a gas supply source, a first buffer section between the chamber and the air supply source, a first air supply valve between the chamber and the first buffer section, and a second air supply valve between the first buffer section and the air supply source, and the control section controls the air supply mechanism so that the first air supply valve is switched from a closed state to an open state while the second air supply valve is kept closed in order to supply the predetermined amount of gas.

A third aspect is a reduced pressure drying apparatus according to the second aspect, in which the air intake mechanism includes a second buffer section between the second air intake valve and the air supply source, and a third air intake valve between the second buffer section and the air supply source, and the control section controls the air intake mechanism so that the first air intake valve is switched from a closed state to an open state while the second air intake valve is kept in a closed state in order to supply the predetermined amount of gas, and then controls the air intake mechanism so that the second air intake valve is switched from a closed state to an open state.

A fourth aspect is a reduced pressure drying apparatus according to any one of the first to third aspects, in which the reduced pressure mechanism includes a vacuum pump and at least one vacuum valve between the chamber and the vacuum pump, and the control unit controls the at least one vacuum valve so that the vacuum pump evacuates the chamber when supplying the predetermined amount of gas.

A fifth aspect is a reduced pressure drying apparatus according to any one of the first to third aspects, in which the reduced pressure mechanism includes a vacuum pump and at least one vacuum valve between the chamber and the vacuum pump, and the control unit controls the at least one vacuum valve so that the vacuum pump is disconnected from the chamber when the predetermined amount of gas is supplied.

A sixth aspect is a reduced pressure drying apparatus according to the fifth aspect, in which the control unit controls the at least one vacuum valve so that the vacuum pump evacuates the chamber after supplying the predetermined amount of gas and before supplying an amount of gas from the air supply mechanism such that the pressure in the chamber becomes atmospheric pressure.

The seventh aspect is a reduced pressure drying method for drying a coating film applied to the upper surface of a substrate, comprising: a first step of reducing the pressure in the chamber by sucking gas from the chamber while cooling a cooling surface that faces the upper surface of the substrate supported by a support part in the chamber and evaporates the solvent from the coating film on the substrate and condenses it on the cooling surface; a second step of increasing the pressure in the chamber by supplying a predetermined amount of gas into the chamber after the first step, evaporating the solvent on the cooling surface and drying the cooling surface; and a third step of supplying an amount of gas such that the pressure in the chamber becomes atmospheric pressure after the second step.

According to each of the above aspects, first, gas is supplied into the chamber in a reduced pressure state before an amount of gas is supplied such that the pressure inside the chamber becomes atmospheric pressure. This promotes evaporation of the solvent condensed on the cooling surface of the cooling unit. This prevents excessive accumulation of liquid solvent on the cooling surface of the cooling unit. Second, the amount of gas supplied is set to a predetermined amount. This allows the amount of gas supplied to be kept to an amount necessary and sufficient to promote the evaporation. This prevents excessive reduction in productivity due to an excessive amount of gas supplied. From the above, it is possible to prevent excessive accumulation of liquid solvent on the cooling surface of the cooling unit while avoiding excessive reduction in productivity.

1 is a diagram illustrating an example of a vertical cross section of a reduced-pressure drying apparatus according to a first embodiment. FIG. 1 is a diagram illustrating an example of a cross section of a reduced pressure drying apparatus according to a first embodiment. FIG. 1 is a diagram showing an example of a vertical cross section of a reduced-pressure drying apparatus according to a first embodiment. FIG. FIG. 2 is a perspective view showing an example of a substrate. FIG. 2 is a diagram showing an example of a vertical cross section of a portion of a substrate. 4 is a block diagram conceptually showing functions realized in a control unit. FIG. 4 is a flowchart showing an example of the flow of a reduced-pressure drying method according to the first embodiment. FIG. 4 is a diagram illustrating an example of a state inside a chamber during a first depressurization process. 4 is an enlarged view showing the vicinity of a cooling surface and a substrate in the chamber during a first depressurization process. FIG. FIG. 13 is an enlarged view showing a top plate portion and a substrate of a chamber according to a comparative structure. FIG. 13 is a diagram showing an example of a concentration distribution of solvent vapor in an upper space in a comparative structure. FIG. 13 is a diagram showing an example of a concentration distribution of solvent vapor in the upper space when the cooling unit is cooling. FIG. 13 is a diagram illustrating an example of a state inside the chamber during a second depressurization process. 5 is a graph illustrating a change in chamber pressure over time in reduced pressure drying according to the first embodiment. FIG. FIG. 11 is a graph illustrating the change in chamber pressure over time in reduced pressure drying of the comparative example. FIG. 11 is a graph illustrating a change in chamber pressure over time in reduced pressure drying according to the second embodiment. FIG. 11 is a diagram illustrating an example of a vertical cross section of a reduced-pressure drying apparatus according to a third embodiment. 13 is a graph illustrating a change in chamber pressure over time in reduced pressure drying according to the third embodiment. FIG. FIG. 13 is a diagram illustrating an example of a vertical cross section of a reduced pressure drying apparatus according to a fourth embodiment. FIG. 13 is a diagram illustrating an example of a vertical cross section of a reduced pressure drying apparatus according to a fifth embodiment. FIG. 13 is a diagram illustrating an example of a vertical cross section of a reduced pressure drying apparatus according to a sixth embodiment. FIG. 23 is a diagram illustrating an example of a vertical cross section of a reduced pressure drying apparatus according to a seventh embodiment.

An embodiment and various modified examples of the present disclosure will be described below with reference to the drawings. In the drawings, parts having similar configurations and functions are given the same reference numerals, and duplicated explanations will be omitted in the following description. The drawings are shown diagrammatically, and the sizes and positional relationships of various structures in each drawing are not accurately illustrated. Furthermore, in this specification, the downward direction is the direction of gravity, and the upward direction is the direction opposite to the direction of gravity. The upward and downward directions are also collectively referred to as the up-down direction. A planar view means a planar layout. A planar layout of a certain component is a two-dimensional layout obtained by projecting the component onto a plane. The plane may be a surface perpendicular to the up-down direction.

<1. First embodiment>
Fig. 1 is a diagram showing an example of a vertical section of the reduced pressure drying apparatus 1 according to the first embodiment. Fig. 2 is a diagram showing an example of a transverse section of the reduced pressure drying apparatus 1 according to the first embodiment. Fig. 3 is a diagram showing an example of a vertical section of the reduced pressure drying apparatus 1 according to the first embodiment. The vertical section in Fig. 1 and the vertical section in Fig. 3 show the configuration of the reduced pressure drying apparatus 1 as viewed from directions different by about 90 degrees. In Fig. 3, configurations related to a decompression mechanism 30, an air supply mechanism 60, a pressure gauge 70, and a control unit 80, which will be described later, are omitted for convenience in order to avoid complication of the drawing.

The reduced pressure drying device 1 is a device that dries the coating film 90 (see Figure 5) formed on the upper surface of the substrate 9.

The substrate 9 may be, for example, a glass substrate, a semiconductor wafer, or a ceramic substrate. The substrate 9 is, for example, a flat substrate having a first surface F1 (see FIGS. 4 and 5) as a first main surface and a second surface F2 (see FIG. 5) as a second main surface opposite to the first surface F1. For example, in the reduced pressure drying device 1, the first surface F1 of the substrate 9 is the upper surface of the substrate 9, and the second surface F2 of the substrate 9 is the lower surface of the substrate 9. Here, a specific example in which a rectangular glass substrate is applied to the substrate 9 will be described as appropriate. A coating film 90 is partially formed on the first surface F1 of the substrate 9 by applying a treatment liquid containing, for example, an organic material and a solvent in advance. The treatment liquid is applied, for example, by a slit coater or an inkjet device. The treatment liquid may be, for example, a liquid containing a polyimide precursor and a solvent (also called a PI liquid) or a coating liquid such as a resist liquid. The polyimide precursor may be, for example, a polyamic acid (polyamic acid). For example, NMP (N-Methyl-2-Pyrrolidone) is used as the solvent. In addition, for example, when the reduced pressure drying apparatus 1 is applied to the manufacturing process of an organic EL display, the coating film 90 may be dried in the reduced pressure drying apparatus 1 to become a hole injection layer, a hole transport layer, or a light emitting layer of an organic EL display panel.

4 is a perspective view showing an example of the substrate 9. FIG. 5 is a view showing an example of a vertical cross section of a portion of the substrate 9. As shown in FIG. 4, the substrate 9 has, for example, a rectangular shape with different vertical and horizontal lengths in a plan view. The substrate 9 may have a plurality of regions A1 in which devices or the like are formed (also called formation regions or coating regions). In the example of FIG. 4, in a top view, four rectangular coating regions A1 are arranged in a matrix of two rows and two columns on the substrate 9. However, the shape, number, and arrangement of the coating regions A1 are not limited to this example. The coating film 90 is formed according to a desired pattern on the upper surface of each coating region A1 by a slit coater or inkjet device in a coating process prior to the reduced pressure drying process by the reduced pressure drying device 1. For example, a circuit pattern is applied to the desired pattern. In FIG. 4, the coating film 90 is shown with the pattern omitted. Without ignoring the pattern, as shown in FIG. 5, the first surface F1 as the upper surface of each coating region A1 may have a region A3 covered with the coating film 90 (also called a covered region) and an exposed region A4 not covered with the coating film 90 (also called an exposed region). In addition, the region around the coating region A1 and between adjacent coating regions A1 on the substrate 9 is a region A2 (also called a non-coated region) where the coating film 90 is not formed on the first surface F1 as the upper surface. The non-coated region A2 is also an exposed region A4 not covered with the coating film 90.

<1-1. Overview of the configuration of the reduced pressure drying device>
Next, a description will be given of an outline of the configuration of the reduced pressure drying apparatus 1. As shown in Figures 1 and 2, the reduced pressure drying apparatus 1 includes a chamber 10, a support unit 20, a reduced pressure mechanism 30, a cooling unit 40, an air supply mechanism 60, and a control unit 80.

The chamber 10 is a portion for housing the substrate 9. The support portion 20 is provided within the chamber 10 and supports the substrate 9 in a horizontal position. The horizontal position here means that the thickness direction of the substrate 9 is aligned in the vertical direction.

The pressure reduction mechanism 30 sucks in the gas in the chamber 10 and expels the gas to the outside of the chamber 10. This suction reduces the pressure in the chamber 10. As the pressure in the chamber 10 decreases, the solvent in the coating film 90 on the first surface F1 of the substrate 9 evaporates, and the coating film 90 dries.

The cooling unit 40 cools the cooling surface 40a. The cooling surface 40a is a surface that faces the first surface F1 of the substrate 9 supported by the support unit 20 in the vertical direction. In the example of FIG. 1, the cooling surface 40a corresponds to the ceiling surface of the chamber 10. The cooling surface 40a may have a size larger than the substrate 9 in a plan view. In other words, the cooling surface 40a may have a size large enough to face the entire first surface F1 of the substrate 9. The cooling surface 40a is, for example, a horizontal flat surface. The cooling unit 40 cools the cooling surface 40a, thereby lowering the temperature of the cooling surface 40a.

The solvent vapor (hereinafter referred to as solvent vapor) evaporated from the coating film 90 on the first surface F1 of the substrate 9 may be cooled and condensed on the cooling surface 40a. As a result, liquid solvent 91 (see also FIG. 8, which will be described later) may adhere to the cooling surface 40a. This condensation can suppress the occurrence of uneven drying of the coating film 90, as will be described in detail later. In addition, a further reduction in the pressure within the chamber 10 can also promote the evaporation of the solvent 91 adhering to the cooling surface 40a. This condensation and evaporation will also be described in detail later.

The air supply mechanism 60 supplies gas into the chamber 10. This allows the pressure inside the chamber 10 to be increased. As will be described in more detail later, the air supply mechanism 60 can increase the pressure to a value below atmospheric pressure, or it can increase the pressure to atmospheric pressure.

In the example of FIG. 1, the reduced pressure drying apparatus 1 further includes a first lifting section 100. The first lifting section 100 lifts and lowers the support section 20. Specifically, the first lifting section 100 lifts and lowers the support section 20 between an upper position H1 and a lower position H2. The upper position H1 is the position of the support section 20 when the distance between the substrate 9 supported by the support section 20 and the cooling surface 40a is a first distance. In the example of FIG. 1, the support section 20 and the substrate 9 located at the upper position H1 are shown by virtual lines. The lower position H2 is the position of the support section 20 when the distance between the substrate 9 supported by the support section 20 and the cooling surface 40a is a second distance wider than the first distance. In other words, the first lifting section 100 lifts and lowers the support section 20 between a first state in which the distance between the substrate 9 and the cooling surface 40a is a first distance, and a second state in which the distance between the substrate 9 and the cooling surface 40a is a second distance. The first interval is, for example, 10 mm or less, and a more specific example is about 5 mm. The second interval may be, for example, 5 times or more, or 10 times or more, the first interval. To explain a specific example of numerical values, the second interval is, for example, 50 mm or more, and a more specific example is about 80 mm.

As will be described in detail later, in the initial stage of decompression, the first lifting unit 100 positions the support unit 20 at the raised position H1. Thereafter, the first lifting unit 100 lowers the support unit 20 to the lowered position H2. The technical significance of this will also be described in detail later.

In the example of Figures 1 and 2, the reduced pressure drying apparatus 1 further includes a bottom surface straightening plate 50, a side surface straightening plate 51, and a pressure gauge 70. The bottom surface straightening plate 50 and the side surface straightening plate 51 are provided in the chamber 10 and straighten the airflow within the chamber 10. The pressure gauge 70 measures the pressure within the chamber 10 and outputs an electrical signal indicating the measurement result to the control unit 80. The control unit 80 controls the various components of the reduced pressure drying apparatus 1 described above.

Next, a detailed example of each component of the reduced pressure drying device 1 will be described.

<1-1-1. Chamber 10>
A pressure-resistant vessel having an internal space 10s for accommodating a substrate 9 is applied to the chamber 10. The chamber 10 is fixed on, for example, an apparatus frame (not shown). The shape of the chamber 10 is, for example, a flat rectangular parallelepiped. The chamber 10 has, for example, a substantially square bottom plate portion 11, four side wall portions 12, and a substantially square top plate portion 13. The four side wall portions 12 connect, for example, four end sides of the bottom plate portion 11 and four end sides of the top plate portion 13 in the up-down direction. For example, one of the four side wall portions 12 is provided with a transfer port 14 and a gate portion (also called a gate valve) 15 for opening and closing the transfer port 14. The gate portion 15 is, for example, linked or connected to an opening/closing drive portion 16. In FIG. 3, the opening/closing drive portion 16 is conceptually shown in order to avoid complication of the drawing. A driving device such as an air cylinder is applied to the opening/closing drive unit 16. Here, for example, by the operation of the opening/closing drive unit 16, the gate unit 15 can move between a position where the loading/unloading opening 14 is closed (also referred to as a closed position) and a position where the loading/unloading opening 14 is open (also referred to as an open position).

Here, for example, when the gate portion 15 is in the closed position, the internal space 10s of the chamber 10 is sealed. For example, when the gate portion 15 is in the open position, the substrate 9 can be loaded into the internal space 10s of the chamber 10 and unloaded from the internal space 10s of the chamber 10 via the loading/unloading port 14.

<1-1-2. Support part 20>
The support part 20 is located in the internal space 10s of the chamber 10, and can support the substrate 9 accommodated in the internal space 10s of the chamber 10 from below. The support part 20 has, for example, a plurality of support plates 21 and a plurality of support pins 22. The plurality of support plates 21 are arranged, for example, at intervals in the horizontal direction. A plurality of support pins 22 are erected on the upper surface of each support plate 21. The plurality of support pins 22 are two-dimensionally distributed and arranged in a plan view. The plurality of support plates 21 are a base part of the support part 20. The substrate 9 is arranged above the plurality of support plates 21, and the upper ends of the plurality of support pins 22 contact the second surface F2 as the lower surface of the substrate 9, thereby supporting the substrate 9 in a horizontal position.

<1-1-3. Pressure reducing mechanism 30>
1 and 2, the bottom plate 11 of the chamber 10 is provided with, for example, four exhaust ports 16a, 16b, 16c, and 16d in a portion facing the substrate 9 in the up-down direction. The decompression mechanism 30 has an exhaust pipe 31, a vacuum pump 32, and at least one vacuum valve between the chamber 10 and the vacuum pump 32. In the example of FIG. 1, the at least one vacuum valve includes four individual valves Va, Vb, Vc, and Vd and a main valve Vm. The exhaust pipe 31 has, for example, four individual pipes 31a, 31b, 31c, and 31d and one main pipe 31e. For example, one end of the individual pipe 31a is connected to the exhaust port 16a, one end of the individual pipe 31b is connected to the exhaust port 16b, one end of the individual pipe 31c is connected to the exhaust port 16c, and one end of the individual pipe 31d is connected to the exhaust port 16d. For example, the other ends of the four individual pipes 31a, 31b, 31c, and 31d are joined together and connected to one end of a main pipe 31e. For example, the other end of the main pipe 31e is connected to a vacuum pump 32. For example, the individual valve Va is provided on the path of the individual pipe 31a, the individual valve Vb is provided on the path of the individual pipe 31b, the individual valve Vc is provided on the path of the individual pipe 31c, and the individual valve Vd is provided on the path of the individual pipe 31d. For example, the main valve Vm is provided on the path of the main pipe 31e.

Here, for example, when the gate unit 15 closes the loading/unloading port 14, at least one of the four individual valves Va, Vb, Vc, and Vd and one main valve Vm are opened, and the vacuum pump 32 is operated, the gas in the chamber 10 is exhausted to the outside of the chamber 10 through the exhaust pipe 31. This allows, for example, the pressure in the internal space 10s of the chamber 10 to be reduced. This puts the chamber 10 in a reduced pressure state. The four individual valves Va, Vb, Vc, and Vd are, for example, valves for individually adjusting the exhaust amount (suction flow rate) from the four exhaust ports 16a, 16b, 16c, and 16d. For example, a valve (also called an on-off valve) that can be switched between an open state and a closed state based on a command from the control unit 80 is applied to each of the four individual valves Va, Vb, Vc, and Vd. The main valve Vm is, for example, a valve for adjusting the total amount of exhaust from the four exhaust ports 16a, 16b, 16c, and 16d. For example, a valve whose opening can be adjusted based on a command from the control unit 80 (also called an opening control valve) is applied to the main valve Vm. In this first embodiment, as described below, when the gas supply mechanism 60 supplies a predetermined amount of gas into the chamber 10, the individual valves Va to Vd and the main valve Vm are controlled by the control unit 80 so that the vacuum pump 32 exhausts the chamber 10.

<1-1-4. First lifting section 100>
In the first embodiment, the first lifting unit 100 lifts and lowers the support unit 20 in the chamber 10. In other words, the first lifting unit 100 has a mechanism (also called a lifting mechanism) that can lift and lower the support unit 20. In FIG. 1, the first lifting unit 100 is conceptually shown to avoid complication of the drawing. A driving device such as a linear motor or an air cylinder is applied to the first lifting unit 100. As shown in FIG. 3, the first lifting unit 100 has, for example, a main body unit 100a and a moving unit 100b. The main body unit 100a is fixed to an apparatus frame (not shown) outside the chamber 10. The moving unit 100b can move, for example, in the vertical direction relative to the main body unit 100a. For example, a rod-shaped member or the like is applied to the moving unit 100b. The moving part 100b is positioned, for example, in a state where it is inserted into the through hole 11h of the bottom plate part 11 of the chamber 10. And, for example, the support part 20 is fixed to the upper end part of the moving part 100b. Here, for example, if a bellows or the like is provided between the lower surface of the bottom plate part 11 and the moving part 100b, the gap between the bottom plate part 11 and the moving part 100b can be sealed. For example, when the supporting part 20 has a plurality of supporting plates 21, the moving part 100b has a rod-shaped part (also called a rod-shaped part) fixed to the supporting plate 21 for each supporting plate 21 and inserted into the through hole 11h of the bottom plate part 11, a part (also called a connecting part) connecting the plurality of rod-shaped parts, and a part (also called a sliding part) connected to the connecting part and slidably supported by the main body part 100a. When the first lifting part 100 lifts and lowers the supporting part 20, the substrate 9 supported by the supporting part 20 also lifts and lowers.

<1-1-5. Cooling section 40>
Although the specific configuration of the cooling unit 40 is not particularly limited, in the example of FIG. 1, the cooling unit 40 includes a cooling member 41, a first refrigerant pipe 42, a second refrigerant pipe 43, and a refrigerant cooling source 44. In FIG. 3, the configuration of the cooling unit 40 is shown in a simplified manner to avoid complication of the drawing. The cooling member 41 has a plate-like shape. In this case, the cooling member 41 may also be called a cooling plate. The cooling member 41 is attached to the upper surface of the top plate portion 13 with its thickness direction aligned along the vertical direction. The cooling member 41 has, for example, a rectangular shape in a plan view. The lower surface of the cooling member 41 may be in close contact with the upper surface of the top plate portion 13. The cooling member 41 may be formed of a material with high thermal conductivity (for example, metal, etc.).

In the example of FIG. 1, a refrigerant flow path 41a is formed inside the cooling member 41. The refrigerant flow path 41a may be, for example, serpentine in a plan view, or may extend in a spiral shape. In the example of FIG. 1, the inlet 41b and outlet 41c of the refrigerant flow path 41a are formed on the upper surface of the cooling member 41. The inlet 41b is connected to the downstream end of the first refrigerant pipe 42, and the outlet 41c is connected to the upstream end of the second refrigerant pipe 43. The upstream end of the first refrigerant pipe 42 and the downstream end of the second refrigerant pipe 43 are connected to the refrigerant cooling source 44.

The refrigerant flows into the refrigerant cooling source 44 from the downstream end of the second refrigerant pipe 43. The refrigerant may be liquid or gas. As a specific example, water can be used as the refrigerant. The refrigerant cooling source 44 cools the refrigerant and supplies the cooled refrigerant to the upstream end of the first refrigerant pipe 42. The refrigerant cooling source 44 may be, for example, a heat pump. The refrigerant cooled by the refrigerant cooling source 44 flows into the upstream end of the first refrigerant pipe 42 and flows into the refrigerant flow path 41a through the first refrigerant pipe 42. As the low-temperature refrigerant flows through the refrigerant flow path 41a, the refrigerant exchanges heat with the cooling member 41 to cool the cooling member 41. Since the cooling member 41 exchanges heat with the top plate portion 13, the top plate portion 13 is also cooled. The refrigerant that flows through the refrigerant flow path 41a and is warmed flows back into the refrigerant cooling source 44 through the second refrigerant pipe 43 and is cooled again by the refrigerant cooling source 44.

When the cooling unit 40 cools the top plate portion 13 of the chamber 10, the cooling surface 40a, which is the lower surface of the top plate portion 13 (i.e., the ceiling surface of the chamber 10), is also cooled. In the example of FIG. 1, the cooling member 41 has a size larger than the substrate 9 in a plan view. That is, the outline of the cooling member 41 surrounds the outline of the substrate 9 in a plan view. When the cooling member 41 has a rectangular shape in a plan view, the long side of the cooling member 41 is longer than the long side of the substrate 9, and the short side of the cooling member 41 is longer than the short side of the substrate 9. This allows the cooling member 41 to appropriately cool the entire surface of the cooling surface 40a that faces the entire first surface F1 of the substrate 9. The rectangular shape may be a square shape. In this case, one side of the cooling member 41 may be longer than the short side of the substrate 9. According to this, regardless of the orientation of the substrate 9 placed on the support portion 20, the cooling member 41 is larger than the substrate 9 in a plan view. Therefore, regardless of the orientation of the substrate 9, the cooling member 41 can appropriately cool the entire surface of the cooling surface 40a that faces the entire first surface F1 of the substrate 9.

<1-1-6. Bottom rectifier plate 50>
The bottom rectifying plate 50 is a plate for regulating the flow of gas in the internal space 10s when the pressure in the chamber 10 is reduced by the decompression mechanism 30. For example, the bottom rectifying plate 50 is disposed so as to be located between the substrate 9 supported by the support portion 20 and the bottom plate portion 11 of the chamber 10. The bottom rectifying plate 50 is fixed to the bottom plate portion 11 of the chamber 10 via a plurality of pillars not shown. As shown in FIG. 2, for example, the bottom rectifying plate 50 has a square shape in a plan view. And, for example, the length of each side of the bottom rectifying plate 50 in a plan view is longer than the short side of the rectangular substrate 9. For this reason, for example, regardless of the orientation of the substrate 9 arranged on the support portion 20, the bottom rectifying plate 50 is larger than the substrate 9 in a plan view. In addition, the bottom rectifying plate 50 has, for example, a through hole 50h through which the moving portion 100b of the first lifting portion 100 is inserted. At the through hole 50h, the bottom flow plate 50 and the moving portion 100b are positioned with a very small gap therebetween.

<1-1-7. Side rectifier plate 51>
The side rectifying plate 51, together with the bottom rectifying plate 50, is a plate for regulating the flow of gas in the internal space 10s when the pressure inside the chamber 10 is reduced by the decompression mechanism 30. For example, the side rectifying plate 51 is arranged so as to be located between the substrate 9 supported by the support part 20 located at the lowered position H2 and the side wall part 12 of the chamber 10. Here, for example, four side rectifying plates 51 are arranged so as to surround the periphery of the substrate 9 supported by the support part 20. For example, the four side rectifying plates 51 as a whole form a rectangular cylindrical rectifying plate surrounding the substrate 9. Also, for example, the bottom rectifying plate 50 and the four side rectifying plates 51 as a whole form a cylindrical box-shaped rectifying plate with a bottom. In the example of FIG. 1, the upper end of the side rectifying plate 51 is located below the second surface F2 of the substrate 9 supported by the support part 20 located at the raised position H1. Therefore, in the first state in which the support portion 20 is located at the raised position H1, the substrate 9 is not surrounded by the four side flow straightening plates 51.

Here, for example, when the pressure inside the chamber 10 is reduced in the second state in which the support portion 20 is located at the lowered position H2, the gas directly above the substrate 9 mainly flows toward the upper end of the side straightening plate 51 (see also FIG. 13 described later). The gas passes through the space between the side straightening plate 51 and the side wall portion 12, the space between the bottom straightening plate 50 and the bottom plate portion 11, and the exhaust ports 16a, 16b, 16c, and 16d in the order described above, and is discharged to the outside of the chamber 10. In this way, the gas flows through a space away from the substrate 9, making it difficult for an air flow to be formed near the substrate 9. And it becomes difficult for a concentrated air flow to occur around the periphery of the substrate 9. This can suppress, for example, the occurrence of uneven drying of the coating film 90 formed on the upper surface of the substrate 9.

Furthermore, as shown in FIG. 2, a configuration is adopted in which the four exhaust ports 16a, 16b, 16c, and 16d are all located on the diagonals 52 of the square-shaped bottom surface straightening plate 50 in a plan view. In this case, for example, each exhaust port 16a, 16b, 16c, and 16d can form an airflow that is symmetrical with respect to the center of the bottom surface straightening plate 50 (the intersection of the two diagonals 52). This can form a more uniform airflow in the internal space 10s of the chamber 10, for example.

<1-1-8. Air supply mechanism 60>
The air supply mechanism 60 is a part that performs the operation of supplying gas (also referred to as air supply) into the chamber 10. As shown in FIG. 1, the bottom plate portion 11 of the chamber 10 is provided with, for example, an air supply port 16f. The air supply port 16f is located, for example, below the bottom surface straightening plate 50. The air supply mechanism 60 is attached to the air supply port 16f of the chamber 10. The air supply mechanism 60 has an air supply source 62 of gas, a buffer portion 63 (first buffer portion) between the air supply port 16f of the chamber 10 and the air supply source 62, an air supply valve V1 (first air supply valve) between the air supply port 16f of the chamber 10 and the buffer portion 63, and an air supply valve V2 (second air supply valve) between the buffer portion 63 and the air supply source 62. These members may be connected by an air supply pipe 61. In FIG. 1, one end of the air supply pipe 61 is connected to the air supply port 16f, and the other end of the air supply pipe 61 is connected to an air supply source 62. A buffer section 63 and air supply valves V1 and V2 are provided on the route of the air supply pipe 61.

Here, first, when both the intake valves V1 and V2 are open, gas is supplied from the intake source 62 to the internal space 10s of the chamber 10 through the intake pipe 61, the buffer section 63, and the intake port 16f. This can increase the pressure in the chamber 10, and can also increase the pressure to atmospheric pressure. Second, when the intake valve V2 is closed and the intake valve V1 is switched from the closed state to the open state while the chamber 10 is in a decompressed state, a predetermined amount of gas stored in the buffer section 63 is supplied from the buffer section 63 to the internal space 10s of the chamber 10 through the intake pipe 61 and the intake port 16f. This can increase the pressure in the chamber 10. The gas stored in the buffer section 63 may have a pressure equivalent to the intake pressure from the intake source 62 before it starts to be supplied to the internal space 10s of the chamber 10. The buffer section 63 is a type of container that can temporarily store a predetermined amount of gas supplied from the air supply source 62, and is, for example, an air supply tank or a pipe that is long enough to have a sufficient internal volume. The volume of the buffer section 63 may be smaller than the volume of the chamber 10. The predetermined amount may be smaller than the amount that allows the chamber 10, which is in a sufficiently reduced pressure state, to reach atmospheric pressure.

The gas supplied from the air supply source 62 may be, for example, an inert gas such as nitrogen gas, or may be clean dry air. Clean dry air may be prepared, for example, by purifying air in a typical environment to remove particles and moisture.

In order to supply the above-mentioned predetermined amount of gas from the air supply mechanism 60 into the chamber 10 in a depressurized state, the air supply mechanism 60 is controlled by the control unit 80 so that the air supply valve V2 is kept closed and the air supply valve V1 is switched from the closed state to the open state. As described above, in this first embodiment, when supplying the above-mentioned predetermined amount of gas, the depressurization mechanism 30 is controlled by the control unit 80 so that the vacuum pump 32 exhausts the chamber 10. In other words, the supply of the above-mentioned predetermined amount of gas into the chamber 10 and the exhaust from the chamber 10 are performed simultaneously. After the above-mentioned predetermined amount of gas is supplied from the air supply mechanism 60 into the chamber 10 in a depressurized state, the air supply mechanism 60 is controlled by the control unit 80 so that an amount of gas is supplied from the air supply mechanism 60 such that the pressure in the chamber 10 becomes atmospheric pressure.

<1-1-9. Pressure gauge 70>
The pressure gauge 70 is a sensor that measures the pressure inside the chamber 10, in other words, the pressure of the internal space 10s of the chamber 10. When a mixed gas is present in the chamber 10, the pressure referred to here means the total pressure. As shown in Fig. 1, the pressure gauge 70 is attached to a part of the chamber 10. The pressure gauge 70 can measure the pressure of the internal space 10s of the chamber 10 and output the measurement result to the control unit 80.

<1-1-10. Control unit 80>
The control unit 80 is a unit (electronic circuit) for controlling the operation of each part of the reduced pressure drying apparatus 1. The control unit 80 can control the configuration of the reduced pressure mechanism 30, the cooling unit 40, the air supply mechanism 60, the first lifting unit 100, and the like. The control unit 80 is configured by a computer having, for example, a processor 801 such as a CPU (Central Processing Unit), a memory 802 such as a RAM (Random Access Memory), and a storage unit 803 such as a hard disk drive. The storage unit 803 stores, for example, a computer program (also called a program) 803p for executing the reduced pressure drying method and various data. The storage unit 803 stores, for example, a program 803p and serves as a non-transient storage medium readable by a computer. The control unit 80 controls the operation of each part of the reduced pressure drying apparatus 1 by, for example, reading the program 803p and data from the storage unit 803 to the memory 802 and performing arithmetic processing according to the program 803p and data in the processor 801. Therefore, for example, the program 803p can be executed by the processor 801 included in the control unit 80 in the reduced pressure drying apparatus 1 to perform the reduced pressure drying method.

The control unit 80 may also be connected to, for example, an input unit 804, an output unit 805, a communication unit 806, and a drive 807. The input unit 804 is, for example, a unit that inputs various signals to the control unit 80 in response to a user's operation, etc. The input unit 804 may include, for example, an operation unit that inputs a signal corresponding to the user's operation, a microphone that inputs a signal corresponding to the user's voice, and various sensors that input signals corresponding to the user's movement. The output unit 805 is, for example, a unit that outputs various information in a manner that can be recognized by the user. The output unit 805 may include, for example, a display unit, a projector, and a speaker. The display unit may be a touch panel integrated with the input unit 804. The communication unit 806 is, for example, a unit that transmits and receives various information to and from an external device such as a server by wired or wireless communication means, etc. For example, the program 803p received from an external device by the communication unit 806 may be stored in the storage unit 803. The drive 807 is a part to which a portable storage medium 807m, such as a magnetic disk or optical disk, can be attached and detached. When the storage medium 807m is attached, the drive 807 exchanges data between the storage medium 807m and the control unit 80. For example, when the storage medium 807m storing the program 803p is attached to the drive 807, the program 803p may be read from the storage medium 807m and stored in the storage unit 803. Here, the storage medium 807m stores the program 803p, for example, and serves as a non-transitory storage medium that can be read by a computer.

Figure 6 is a block diagram conceptually illustrating the functions realized by the control unit 80. As shown in Figure 6, the control unit 80 is electrically connected to, for example, the opening/closing drive unit 16, the first lifting unit 100, the four individual valves Va, Vb, Vc, Vd, the main valve Vm, the vacuum pump 32, the air supply valves V1, V2, the cooling unit 40, and the pressure gauge 70. The control unit 80 can control the operation of each of the above-mentioned units, for example, by referring to the measurement values output from the pressure gauge 70.

6, the control unit 80 has, for example, an opening/closing control unit 81, a lifting control unit 82, a switching control unit 83, an exhaust control unit 84, a pump control unit 85, an air supply control unit 86, and a cooling control unit 87 as functional configurations to be realized. For example, the opening/closing control unit 81 controls the operation of the opening/closing drive unit 16. For example, the lifting control unit 82 controls the operation of the first lifting unit 100. For example, the switching control unit 83 individually controls the opening/closing state of the four individual valves Va, Vb, Vc, and Vd. For example, the exhaust control unit 84 controls the opening/closing state and the opening degree of the main valve Vm. For example, the pump control unit 85 controls the operation of the vacuum pump 32. For example, the air supply control unit 86 controls the opening/closing state of the air supply valves V1 and V2. For example, the cooling control unit 87 controls the operation of the cooling unit 40. The functions of each unit in the control unit 80 are realized, for example, by the processor 801 performing arithmetic processing according to the above-mentioned program 803p, etc.

<1-2. Reduced pressure drying method>
Next, a reduced-pressure drying method for drying the coating film 90 applied to the upper surface of the substrate 9 using the reduced-pressure drying apparatus 1 will be described. Fig. 7 is a flow chart showing an example of the flow of the reduced-pressure drying method according to the first embodiment. The flow of the reduced-pressure drying method is realized, for example, by executing a program 803p in a processor 801 included in the control unit 80. Here, for example, the processes from step S10 to step S60 in Fig. 7 are performed in the order described.

In step S10, the substrate 9 is loaded into the chamber 10. At this time, an undried coating film 90 is formed on the first surface F1 of the substrate 9. In step S10, for example, the gate unit 15 opens the loading/unloading port 14 under the control of the control unit 80, and a transport robot (not shown) loads the substrate 9 on a fork-shaped hand and loads the substrate 9 into the internal space 10s of the chamber 10 through the loading/unloading port 14 of the chamber 10. At this point, the support unit 20 is located, for example, in the lowered position H2. The side straightening plate 51 may be configured to be movable so that it does not interfere with the transport robot. For example, the transport robot loads the substrate 9 on the support unit 20 while inserting a fork-shaped hand between the multiple support plates 21 of the support unit 20, and then retracts the fork to the outside of the chamber 10. Then, the gate unit 15 closes the loading/unloading port 14 under the control of the control unit 80. As described above, in step S10, a process (also called a placing process) is performed in which the substrate 9 is placed on a plurality of support pins 22 arranged in the chamber 10. Note that, as an example of the state of the valves at the time of step S10, the individual valves Va to Vd, the main valve Vm, and the air supply valves V1 and V2 are in a closed state.

In step S20, while the cooling surface 40a facing and spaced apart from the upper surface of the substrate 9 supported by the support portion 20 in the chamber 10 is cooled, the pressure in the chamber 10 is reduced by sucking gas from the chamber 10, and the solvent is evaporated from the coating film 90 on the substrate 9 and condensed on the cooling surface 40a. Specifically, the following process is performed.

The control unit 80 operates the cooling unit 40, which causes the cooling unit 40 to cool the cooling surface 40a and reduce the temperature of the cooling surface 40a. The cooling unit 40 reduces the temperature of the cooling surface 40a to a target temperature. The target temperature is, for example, 5 degrees Celsius or higher and 20 degrees Celsius or lower. As a more specific example, the target temperature is about 15 degrees Celsius. The cooling unit 40 may continue the cooling operation on the cooling surface 40a until the processing of the substrate 9 is completed. Note that this cooling operation by the cooling unit 40 may be started prior to step S10.

Next, the reduced pressure drying apparatus 1 performs a first gap adjustment process. The first gap adjustment process is a process for adjusting the gap between the substrate 9 and the cooling surface 40a to a first gap. Specifically, the control unit 80 controls the first lifting unit 100 to raise the support unit 20 to the raised position H1. In the first state in which the support unit 20 is located at the raised position H1, the substrate 9 is located above the upper end of the side straightening plate 51 (see also FIG. 1).

Next, the reduced pressure drying apparatus 1 performs a first decompression process by opening at least one of the individual valves Va to Vd and the main valve Vm while operating the vacuum pump 32. The first decompression process is a process for lowering the pressure in the chamber 10 to a first pressure (hereinafter referred to as the first target pressure). The first target pressure is set to be lower than the standard atmospheric pressure, for example, 10 kPa or higher. Specifically, the control unit 80 lowers the pressure in the chamber 10 by having the decompression mechanism 30 suck in the gas in the chamber 10 at a small first suction flow rate. For example, the control unit 80 may reduce the opening of the main valve Vm to a smaller opening than during the second decompression process described below. In this way, in the first decompression process, the pressure in the chamber 10 decreases at a slower rate. Note that, as an example of the state of the valves during this process, the individual valves Va to Vd and the main valve Vm are open, and the air supply valves V1 and V2 are closed. For example, the control unit 80 may individually and appropriately control the open/closed state of each of the multiple individual valves Va, Vb, Vc, and Vd. This allows the airflow in the chamber 10 to be controlled so as to prevent uneven drying of the substrate 9.

Figures 8 and 9 are schematic diagrams showing an example of the state inside the chamber 10 during the first decompression process. Figure 8 shows the entire chamber 10, and Figure 9 shows an enlarged view of the cooling surface 40a and the vicinity of the substrate 9 inside the chamber 10.

As shown in FIG. 8, in the first decompression process, in the first state in which the support part 20 is located at the raised position H1, the distance between the substrate 9 and the cooling surface 40a is very narrow. Therefore, the rate at which the pressure in the upper space 10s1 decreases becomes slower, and the occurrence of bumping in the coating film 90 on the first surface F1 of the substrate 9 can be suppressed.

On the other hand, in the first state, the substrate 9 supported by the support portion 20 is located above the upper end of the side straightening plate 51. Therefore, the straightening function of the side straightening plate 51 hardly works on the upper space 10s1 between the substrate 9 and the cooling surface 40a. Therefore, the side straightening plate 51 does not have much effect on suppressing the occurrence of uneven drying. In the first state, the lower space 10s2 below the substrate 9 is wide, so the gas in the lower space 10s2 is quickly exhausted. Specifically, the gas in the lower space 10s2 passes between the side straightening plate 51 and the side wall portion 12 of the chamber 10 and is exhausted from the chamber 10. In FIG. 8, this airflow is shown diagrammatically by dashed arrows.

The first decompression process reduces the pressure in the chamber 10, so that the solvent in the coating film 90 on the first surface F1 of the substrate 9 evaporates. In FIG. 9, the flow of solvent vapor from the coating film 90 is shown by dashed arrows. In the first decompression process, the cooling unit 40 cools the cooling surface 40a, so that the solvent vapor from the coating film 90 is cooled and condensed on the cooling surface 40a. That is, as shown in FIG. 9, liquid solvent 91 adheres to the cooling surface 40a. In other words, the target temperature of the cooling surface 40a is set to a temperature at which the solvent vapor condenses when the pressure in the chamber 10 is the first target pressure. As a more specific example, the target temperature of the cooling surface 40a is set to a temperature at which the pressure becomes the first target pressure on the vapor pressure curve of the solvent. As a result, the solvent 91 can be adhered almost uniformly to the area of the cooling surface 40a that faces the coating film 90. In this way, the solvent vapor in the upper space 10s1 condenses on the cooling surface 40a, decreasing the concentration of the solvent vapor in the upper space 10s1, and the concentration distribution of the solvent vapor when viewed from above becomes more uniform.

For comparison, a comparative structure in which a cooling unit 40 is not provided will be described. FIG. 10 is an enlarged view of the top plate 13 and substrate 9 of the chamber 10 in the comparative structure. In the example of FIG. 9, the lower surface 13a of the top plate 13 of the chamber 10 is not cooled by the cooling unit 40. The temperature of the lower surface 13a of the top plate 13 is, for example, approximately room temperature.

In the first decompression process, the gap between the substrate 9 and the lower surface 13a is narrow, so the solvent vapor from the coating film 90 immediately collides with the lower surface 13a of the top plate portion 13. For this reason, the solvent vapor is likely to remain in the central region of the upper space 10s1 that faces the central portion of the coating film 90. On the other hand, in the peripheral region of the upper space 10s1 that faces the peripheral portion of the coating film 90, the solvent vapor can flow out horizontally due to concentration diffusion. For this reason, the peripheral portion of the coating film 90 is more likely to evaporate than the central portion. In other words, uneven drying of the coating film 90 may occur.

Figure 11 is a diagram showing an example of the concentration distribution of solvent vapor in the upper space 10s1 in the comparative structure. Figure 11(a) shows the concentration distribution of solvent vapor in a top view, and Figure 11(b) shows the concentration distribution of solvent vapor in a side view. In Figure 11(a), the concentration distribution of solvent vapor is shown by contour lines T1 to T10. The smaller the number of the symbol of the contour lines T1 to T10, the higher the concentration. In other words, the contour line T1 shows the highest concentration between the contour lines T1 to T10. In Figure 11(b), the concentration distribution of solvent vapor is shown by contour lines T11 to T21. The smaller the number of the symbol of the contour lines T11 to T21, the higher the concentration. In other words, the contour line T11 shows the highest concentration between the contour lines T11 to T21.

As can be seen from FIG. 11(a), in the comparative structure, solvent vapor flows from the periphery of the coating film 90 to the outside. Also, as shown in FIG. 11(b), in the peripheral region 10r of the upper space 10s1 that faces the peripheral portion of the coating film 90, the concentration of solvent vapor decreases toward the outside of the coating film 90. For this reason, it can be seen that the peripheral portion of the coating film 90 is more likely to evaporate than the central portion.

Figure 12 is a diagram showing an example of the concentration distribution of the solvent vapor in the upper space 10s1 when the cooling unit 40 is cooling. Figure 12(a) shows the concentration distribution of the solvent vapor in a top view, and Figure 12(b) shows the concentration distribution of the solvent vapor in a side view. As can be seen from Figure 12(a), the solvent vapor does not flow outward from the periphery of the coating film 90 very much. This is because the solvent vapor from the coating film 90 is cooled and condensed on the cooling surface 40a. In other words, both the solvent vapor from the central part of the coating film 90 and the solvent vapor from the peripheral part flow upward with an ascending air current according to the temperature difference with the cooling surface 40a and condense on the cooling surface 40a (see also Figure 9). In this way, the solvent vapor from the peripheral part also condenses on the cooling surface 40a, so there is not much outward flow of the solvent vapor. In addition, the solvent vapor from the coating film 90 does not remain in the upper space 10s1 very much.

As shown in FIG. 12(b), even in the peripheral region 10r, the concentration of solvent vapor decreases with increasing distance from the coating film 90 in the vertical direction, but is almost uniform in the horizontal direction.

This reduces the difference between the amount of evaporation in the central portion and the amount of evaporation in the peripheral portion of the coating film 90, thereby suppressing the occurrence of uneven drying. In addition, the condensation of the solvent vapor on the cooling surface 40a reduces the concentration of the solvent vapor in the upper space 10s1, which can promote the evaporation of the coating film 90. This can also improve the throughput of the reduced pressure drying method.

After step S20, in step S30, the solvent is further evaporated from the coating film 90. The transition from step S20 to step S30 is performed, for example, when the pressure in the chamber 10 reaches the first target pressure. Specifically, the following process is performed to promote this evaporation.

The reduced pressure drying device 1 performs a second gap adjustment process. The second gap adjustment process is a process for adjusting the gap between the substrate 9 and the cooling surface 40a to a second gap. Specifically, the control unit 80 controls the first lifting unit 100 to lower the support unit 20 to the lowered position H2. In the second state in which the support unit 20 is located at the lowered position H2, the substrate 9 is located below the upper end of the side straightening plate 51.

Next, the reduced pressure drying apparatus 1 performs a second decompression process. The second decompression process is a process for lowering the pressure in the chamber 10 to a second pressure (hereinafter referred to as the second target pressure) lower than the first target pressure. Specifically, the control unit 80 reduces the pressure in the chamber 10 by having the decompression mechanism 30 suck the gas in the chamber 10 at a second suction flow rate greater than the first suction flow rate. For example, the control unit 80 may increase the opening of the main valve Vm to a value greater than that during the first decompression process. The pressure in the chamber 10 is reduced to the second target pressure at a rate greater than that during the first decompression process. In the second decompression process, the reduced pressure drying apparatus 1 may maintain the pressure in the chamber 10 at the second target pressure for a predetermined period of time. The second target pressure is, for example, less than 10 kPa and equal to or greater than 0.1 Pa.

In step S30, for example, the control unit 80 may individually and appropriately control the open/closed state of each of the multiple individual valves Va, Vb, Vc, and Vd. This allows the airflow in the chamber 10 to be controlled so as to suppress uneven drying of the substrate 9.

Figure 13 is a schematic diagram showing an example of the state inside the chamber 10 during the second decompression process. As shown in Figure 13, in the second state in which the support part 20 is located at the lowered position H2, the distance between the substrate 9 and the cooling surface 40a is wide. In other words, the height of the upper space 10s1 is large. Therefore, unlike the first decompression process, the solvent vapor from the coating film 90 tends to flow upward, and the solvent vapor is less likely to stagnate. Because the upper space 10s1 is large, the pressure inside the upper space 10s1 can be more appropriately and quickly reduced to the second target pressure.

In addition, in the second state, the substrate 9 supported by the support portion 20 is surrounded by four side straightening plates 51. Therefore, the straightening function of the side straightening plates 51 acts on the upper space 10s1 between the substrate 9 and the cooling surface 40a. In other words, the side straightening plates 51 can suppress the concentration of airflow on the peripheral portion of the substrate 9. Therefore, the occurrence of uneven drying of the coating film 90 due to airflow can be further suppressed.

When the pressure in the chamber 10 reaches the second target pressure, the solvent in the coating film 90 boils and the coating film 90 dries at a higher speed. The decompression mechanism 30 may suck the gas in the chamber 10 so that the pressure in the chamber 10 is substantially constant at the second target pressure. In other words, the decompression mechanism 30 may maintain the pressure in the chamber 10 at the second target pressure for a predetermined period of time. In the second decompression process, the target temperature of the cooling surface 40a may be set to a temperature at which the solvent evaporates when the pressure in the chamber 10 reaches the second target pressure, and the solvent 91 attached to the cooling surface 40a also evaporates. As a more specific example, the target temperature of the cooling surface 40a may be set to a temperature at which the pressure reaches the second target pressure on the vapor pressure curve of the solvent.

The solvent vapor from the coating film 90 and the cooling surface 40a flows from the upper end side of the side straightening plate 51 into the space between the side straightening plate 51 and the side wall portion 12 of the chamber 10, and is exhausted to the outside through the exhaust ports 16a, 16b, 16c, and 16d. In Figure 13, the flow of these solvent vapors is shown diagrammatically by dashed arrows.

When the boiling of the coating film 90 has finished, that is, after a predetermined period of time has elapsed, the pressure reduction mechanism 30 may further reduce the pressure in the chamber 10. In other words, the pressure reduction mechanism 30 may reduce the pressure in the chamber 10 to a third target pressure that is lower than the second target pressure. This can further promote the drying of the coating film 90 and the evaporation of the solvent 91 adhering to the cooling surface 40a.

As described above, in the second decompression process, the first lifting unit 100 lowers the support unit 20 to the lowered position H2, and the decompression mechanism 30 reduces the pressure in the chamber 10 to the second target pressure or less. This allows the reduced-pressure drying device 1 to dry the coating film 90 on the first surface F1 of the substrate 9 in the second decompression process. This also allows the evaporation of the solvent 91 attached to the cooling surface 40a to be promoted. However, the evaporation of the solvent 91 proceeds relatively slowly, and therefore, if one were to rely solely on the second decompression process to sufficiently dry the cooling surface 40a, the second decompression process would have to be carried out for a long time, resulting in reduced productivity. Therefore, in order to dry the cooling surface 40a in a shorter time, the following step S40 is carried out.

In step S40, a predetermined amount of gas is supplied into the chamber 10 to increase the pressure in the chamber 10, evaporating the solvent on the cooling surface 40a and thoroughly drying the cooling surface 40a. Specifically, in order to supply the predetermined amount of gas from the gas supply mechanism 60 into the chamber 10, which is in a reduced pressure state, the gas supply valve V2 is kept closed while the gas supply valve V1 is switched from a closed state to an open state. In this first embodiment, when supplying the predetermined amount of gas, the decompression mechanism 30 is controlled so that the vacuum pump 32 evacuates the chamber 10. In other words, the supply of the predetermined amount of gas into the chamber 10 and the exhaust from the chamber 10 are performed simultaneously.

When gas is supplied into the chamber 10 in a reduced pressure state, first, an increase in entropy occurs due to mixing of the solvent vapor with the gas in the chamber 10, which is thought to promote the conversion of the liquid solvent 91 adhering to the cooling surface 40a to vapor. Second, the supplied gas causes an increase in temperature in the chamber 10, which is also thought to promote the evaporation of the solvent 91 adhering to the cooling surface 40a. Third, in this first embodiment, the gas is exhausted while being supplied, which promotes the exhaust of the solvent vapor from within the chamber 10, which is also thought to promote the evaporation of the solvent 91 adhering to the cooling surface 40a. The above-mentioned predetermined amount of gas is set to an amount large enough to sufficiently promote the evaporation of the solvent 91.

FIG. 14 is a graph illustrating the change in pressure in the chamber 10 over time from the end of step S20 to step S60, which will be described later. In step S40, the pressure has a peak due to the supply of the predetermined amount of gas. From just before the peak to the peak, the pressure in the chamber 10 may change from a state lower than the vapor pressure p _S of the solvent at the temperature of the cooling surface 40a (see the dashed line in FIG. 14) to a state higher than the peak, but in that case, it is preferable that the pressure is returned to a state lower than the vapor pressure p _S again immediately after the peak. Therefore, in order not to excessively extend the time required for the entire step S40, it is preferable not to excessively increase the peak pressure in step S40. This peak pressure may be lower than atmospheric pressure and lower than the first target pressure described above. It is preferable that the predetermined amount of gas is not excessive so that such pressure conditions are satisfied.

Figure 15 is a graph showing the change in pressure over time in a comparative example in which step S30C is performed instead of steps S30 and S40 (Figure 14) in the first embodiment. Step S30C (Figure 15) extends the time of step S30 (Figure 14) by the time of step S40 (Figure 14). Therefore, the time required for one reduced pressure drying method is the same in the first embodiment and the comparative example. In particular, in the latter half of step S30C in the comparative example, there is almost no gas other than the solvent vapor in the chamber 10, and the evaporation rate of the solvent 91 is slower than that of step S40 in the first embodiment. As a result, even at the end of step S30C, liquid solvent 91 is likely to remain on the cooling surface 40a. Even if this remaining amount is negligible after one reduced pressure drying method is performed, when the reduced pressure drying method is repeatedly performed, liquid solvent 91 accumulates on the cooling surface 40a. If the accumulated liquid solvent 91 falls onto the substrate 9, the quality of the product using the substrate 9 will be impaired. This problem could be solved by extending the time for step S30C, but this would likely result in a significant decrease in productivity.

In step S50, gas is supplied in an amount such that the pressure inside the chamber 10 becomes atmospheric pressure. Specifically, while the individual valves Va-Vd and the main valve Vm are controlled to block the connection between the vacuum pump 32 and the chamber 10, not only the air supply valve V1 but also the air supply valve V2 is opened. This causes gas to be supplied from the air supply source 62 to the internal space 10s of the chamber 10. As a result, the pressure inside the chamber 10 rises again to atmospheric pressure.

In step S60, the substrate 9 is removed from the chamber 10. For example, first, the gate unit 15 opens the loading/unloading opening 14 under the control of the control unit 80, and a transport robot (not shown) removes the dried substrate 9 placed on the support unit 20 to the outside of the chamber 10 via the loading/unloading opening 14 of the chamber 10. This may complete the processing of one substrate 9.

<1-3. Effects>
According to the first embodiment, first, before the amount of gas that brings the pressure in the chamber 10 to atmospheric pressure is supplied, gas is supplied into the chamber 10 in a decompressed state. This promotes evaporation of the solvent condensed on the cooling surface 40a of the cooling unit 40. Therefore, excessive accumulation of liquid solvent on the cooling surface 40a of the cooling unit 40 is avoided. Second, the amount of gas supplied is set to a predetermined amount. This allows the amount of gas supplied to be suppressed to an amount necessary and sufficient for promoting the evaporation. Therefore, excessive reduction in productivity due to an excessive amount of gas supplied can be avoided. From the above, excessive reduction in productivity can be avoided while avoiding excessive accumulation of liquid solvent on the cooling surface 40a of the cooling unit 40.

If the buffer section 63 and the air supply valve V2 were omitted from the reduced pressure drying apparatus 1 (Figure 1), it would be difficult to supply a predetermined amount of gas into the chamber 10 in a reduced pressure state as in the first embodiment, because it would be difficult to stably control the amount of gas supplied. If the amount of gas is insufficient, the above-mentioned effects of the gas cannot be fully obtained. If an attempt is made to supply a large amount of gas in an attempt to ensure a sufficient amount, the resulting airflow would easily shift the substrate 9 from its normal position, cause it to fall, or damage it.

In addition, in this first embodiment, when a predetermined amount of gas is supplied, the vacuum pump 32 evacuates the chamber 10. This allows the pressure in the chamber 10, which has increased due to the supply of gas, to be quickly reduced.

The control unit 80 may control the first lifting unit 100 and the pressure reducing mechanism 30 so that the pressure in the chamber 10 is a first pressure in a first state in which the distance between the substrate 9 and the cooling surface 40a is a first distance, and then the pressure in the chamber 10 is a second pressure in a second state in which the distance between the substrate 9 and the cooling surface 40a is a second distance.

Specifically, first, in the first decompression process, the cooling unit 40 cools the cooling surface 40a, and the first lifting unit 100 raises the support unit 20 to the raised position H1, and the decompression mechanism 30 may reduce the pressure in the chamber 10 to the first target pressure. In the first decompression process, since the support unit 20 is located at the raised position H1, the distance between the substrate 9 and the cooling surface 40a is narrow. Therefore, a sudden decrease in pressure in the upper space 10s1 between the substrate 9 and the cooling surface 40a can be suppressed, and bumping of the coating film 90 can be suppressed.

In addition, in the first decompression process, the cooling unit 40 may cool the cooling surface 40a. More specifically, the cooling unit 40 may lower the temperature of the cooling surface 40a to a target temperature at which the solvent vapor condenses under the first target pressure. As a result, the solvent vapor from the coating film 90 on the substrate 9 condenses on the cooling surface 40a. This makes it possible to suppress the retention of solvent vapor in the upper space 10s1 (particularly the central region), and to suppress the occurrence of uneven drying of the coating film 90.

On the other hand, in the second decompression process after the first decompression process, the decompression mechanism 30 may reduce the pressure in the chamber 10 to the second target pressure or lower while the first lifting unit 100 has lowered the support unit 20 to the lowered position H2. Because the support unit 20 is located at the lowered position H2, the gap between the substrate 9 and the cooling surface 40a is wide. This allows the pressure in the chamber 10 to be reduced more appropriately and quickly. Therefore, the coating film 90 can be dried more appropriately and quickly. In addition, because the gap between the substrate 9 and the cooling surface 40a is wide in the second decompression process, solvent vapor is less likely to remain and uneven drying is less likely to occur.

In addition, in the second decompression process, the temperature of the cooling surface 40a may be a temperature at which the solvent evaporates under the second target pressure. Therefore, in the second decompression process, not only the coating film 90 on the substrate 9 but also the cooling surface 40a can be dried. Therefore, there is no need to separately dry the cooling surface 40a before processing the next substrate 9, and the next substrate 9 can be processed quickly. This improves the throughput of processing multiple substrates 9.

In addition, in the first embodiment, the ceiling surface of the chamber 10 may correspond to the cooling surface 40a. Therefore, if the cooling unit 40 is attached externally to the upper surface of the chamber 10, the existing chamber 10 can be used as is.

In the first embodiment, the cooling member 41 may cool the top plate 13, thereby cooling the cooling surface 40a, which is the lower surface of the top plate 13. Although the temperature distribution in the cooling member 41 when viewed from above may vary slightly depending on the extension shape of the refrigerant flow path 41a, the variation in temperature distribution is mitigated toward the cooling surface 40a due to heat transfer in the top plate 13. In other words, the temperature distribution on the cooling surface 40a of the top plate 13 can be made more uniform. Therefore, the solvent vapor from the coating film 90 on the first surface F1 of the substrate 9 can be more uniformly condensed on the cooling surface 40a. Therefore, the uniformity of the concentration distribution of the solvent vapor in the upper space 10s1 can be increased. This can further suppress the occurrence of drying unevenness.

In addition, in the first embodiment, the first lifting unit 100 that raises and lowers the support unit 20 may be used to adjust the gap between the substrate 9 and the cooling surface 40a. Therefore, the existing first lifting unit 100 can be used as is.

<2. Second embodiment>
FIG. 16 is a graph illustrating a change in pressure in the chamber 10 over time during reduced pressure drying in the second embodiment. In the second embodiment, step S40 (FIG. 7) includes steps S40a and S40b (FIG. 16). In step S40a (FIG. 16), unlike the first embodiment described above, when the gas supply mechanism 60 supplies a predetermined amount of gas into the chamber 10, the individual valves Va to Vd and the main valve Vm are controlled by the control unit 80 so that the vacuum pump 32 is disconnected from the chamber 10. For example, the individual valves Va to Vd and the main valve Vm are closed. Then, the predetermined amount of gas is supplied from the gas supply mechanism 60 into the chamber 10. Thereafter, in step S40b (FIG. 16), the individual valves Va to Vd and the main valve Vm are controlled by the control unit 80 so that the vacuum pump 32 evacuates the chamber 10. For example, the individual valves Va to Vd and the main valve Vm are opened. The supply (step S40a) and exhaust (step S40b) of gas have the effect of replacing the atmosphere inside the chamber 10. After step S40, steps S50 and S60 are performed in the same manner as in the first embodiment.

According to the second embodiment, when a predetermined amount of gas is supplied, the vacuum pump 32 is blocked from the chamber 10. This allows the effect of the supplied gas to be exerted more reliably.

<3. Third embodiment>
<3-1. Overview of the configuration of the reduced pressure drying device>
Fig. 17 is a diagram showing an example of a vertical cross section of a reduced-pressure drying apparatus 1T according to the third embodiment. The air intake mechanism 60M (Fig. 17) of the reduced-pressure drying apparatus 1T includes, in addition to the configuration of the air intake mechanism 60 (Fig. 1: first embodiment) of the reduced-pressure drying apparatus 1, a buffer section 64 (second buffer section) between the air intake valve V2 and the air intake source 62, and an air intake valve V3 (third air intake valve) between the buffer section 64 and the air intake source 62.

The control unit 80 of the reduced pressure drying apparatus 1T controls the air intake mechanism 60M so that the air intake valve V1 is switched from the closed state to the open state while the air intake valve V2 is kept closed in order to supply a predetermined amount of gas, and then controls the air intake mechanism 60M so that the air intake valve V2 is switched from the closed state to the open state. As a result, first, by switching the air intake valve V1 from the closed state to the open state while keeping the air intake valve V2 closed, a part of the predetermined amount of gas is supplied from the buffer unit 63 to the chamber 10 in a reduced pressure state. Then, by switching the air intake valve V2 from the closed state to the open state while keeping the air intake valve V3 closed, the other part of the predetermined amount of gas is supplied from the buffer unit 64 to the chamber 10 in a reduced pressure state. The gas stored in the buffer unit 64 may have a pressure equivalent to the supply pressure from the air intake source 62 before it starts to be supplied to the internal space 10s of the chamber 10.

Note that features other than those mentioned above are similar to those of the first or second embodiment described above, so their description will be omitted.

<3-2. Reduced pressure drying method>
18 is a graph illustrating a change in pressure in the chamber 10 over time during reduced pressure drying according to the third embodiment. In the reduced pressure drying method using the reduced pressure drying apparatus 1T, step S40 (FIG. 7) includes steps S40h and S40i.

In step S40h, in order to supply a portion of the predetermined amount of gas from the gas supply mechanism 60M into the chamber 10, which is in a reduced pressure state, the gas supply valve V1 is switched from a closed state to an open state while the gas supply valve V2 is kept closed. This causes the gas stored in the buffer section 63 to be supplied into the chamber 10. In this third embodiment, the decompression mechanism 30 is controlled so that the vacuum pump 32 evacuates the chamber 10 when supplying a portion of the predetermined amount of gas. In other words, the supply of a portion of the predetermined amount of gas into the chamber 10 and the exhaust of gas from the chamber 10 are performed simultaneously.

After that, in step S40i, in order to supply the other portion of the predetermined amount of gas from the gas supply mechanism 60M into the chamber 10, which is in a reduced pressure state, the gas supply valve V2 is switched from the closed state to the open state in addition to the gas supply valve V1 while the gas supply valve V3 is kept closed. This causes the gas stored in the buffer section 64 to be supplied into the chamber 10. In this third embodiment, when the other portion of the predetermined amount of gas is supplied, the decompression mechanism 30 is controlled so that the vacuum pump 32 evacuates the chamber 10. In other words, the supply of the other portion of the predetermined amount of gas into the chamber 10 and the exhaust from the chamber 10 are performed simultaneously.

<3-3. Effects>
According to the third embodiment, the action described in the first embodiment can be exerted twice instead of once, thereby further enhancing the effect described in the first embodiment.

3-4. Modified Examples
The technique of the third embodiment may be applied to the second embodiment instead of the first embodiment described above. Specifically, in step S40, the decompression mechanism 30 is controlled so that the vacuum pump 32 and the chamber 10 are disconnected from each other during a first supply period in which a part of the predetermined amount of gas is supplied and during a second supply period in which the other part of the predetermined amount of gas is supplied. In addition, the decompression mechanism 30 is controlled so that the vacuum pump 32 evacuates the chamber 10 during each of the timing between the first supply period and the second supply period and the timing after the second supply period. According to this modification, the effect described in the second embodiment can be further enhanced.

<4. Fourth embodiment>
FIG. 19 is a diagram showing an example of a vertical cross section of the reduced pressure drying apparatus 1A according to the fourth embodiment. The reduced pressure drying apparatus 1A has the same configuration as the reduced pressure drying apparatus 1 except for the second lifting section 45. The second lifting section 45 lifts and lowers the cooling member 41 of the cooling section 40 between the cooling position H3 and the separated position H4. The cooling position H3 is a position where the lower surface of the cooling member 41 contacts the upper surface of the top plate section 13 of the chamber 10, and the separated position H4 is a position where the cooling member 41 is separated from the top plate section 13. In the example of FIG. 19, the cooling member 41 located at the separated position H4 is shown in a virtual line. A driving device such as a linear motor or an air cylinder is applied to the second lifting section 45.

The reduced pressure drying method according to the fourth embodiment differs from that according to the first embodiment in that the position of the cooling member 41 is controlled. The cooling member 41 is initially located at the cooling position H3. Then, at a timing between the second interval adjustment process and the second reduced pressure process in the reduced pressure drying according to the first embodiment described above, the reduced pressure drying apparatus 1A performs a cooling unit separation process. The cooling unit separation process is a process for moving the cooling unit 40 to the separation position H4. Specifically, the control unit 80 controls the second lifting unit 45 to raise the cooling member 41 from the cooling position H3 to the separation position H4. By raising the cooling member 41 to the separation position H4, the cooling operation on the cooling surface 40a can be substantially interrupted.

As described above, according to the fourth embodiment, in the first decompression process, the cooling member 41 descends to the cooling position H3 and cools the cooling surface 40a, which is the lower surface of the top plate portion 13. Therefore, the reduced pressure drying apparatus 1A can more reliably condense the solvent vapor on the cooling surface 40a in the first decompression process. Moreover, according to the fourth embodiment, in the second decompression process, the cooling member 41 ascends to the separated position H4. Therefore, in the second decompression process, the cooling operation on the cooling surface 40a can be substantially interrupted. As the cooling member 41 moves away from the cooling surface 40a, the temperature of the cooling surface 40a increases over time, and the evaporation of the solvent 91 attached to the cooling surface 40a can be promoted.

<5. Fifth embodiment>
20 is a diagram illustrating an example of a vertical cross section of a reduced pressure drying apparatus 1B according to a fifth embodiment. The reduced pressure drying apparatus 1B has a similar configuration to the reduced pressure drying apparatus 1 except for the internal configuration of the cooling section 40.

20, a part of the cooling section 40 of the reduced pressure drying apparatus 1B is embedded in the top plate 13 of the chamber 10. Here, the top plate 13 functions as the cooling member 41. The top plate 13 may be made of a material with high thermal conductivity (e.g., metal). In the example of FIG. 20, a refrigerant flow path 41a, which is a part of the cooling section 40, is formed inside the top plate 13. The refrigerant flow path 41a may meander inside the top plate 13 in a plan view, or may extend in a spiral shape. In the example of FIG. 20, the inlet 41b and the outlet 41c of the refrigerant flow path 41a are formed on the upper surface of the top plate 13. The inlet 41b is connected to the downstream end of the first refrigerant pipe 42, and the outlet 41c is connected to the upstream end of the second refrigerant pipe 43.

The refrigerant cooling source 44 cools and circulates the refrigerant, thereby cooling the top plate 13 of the chamber 10. In other words, the cooling surface 40a, which is the underside of the top plate 13, is cooled. Note that a portion of the cooling section 40 embedded in the top plate 13 is a low-temperature portion that absorbs heat from the top plate 13. For example, if the cooling section 40 has a cooling element such as a Peltier element, the cooling element is embedded in the top plate 13.

An example of the flow of the reduced pressure drying method using the reduced pressure drying device 1B is similar to the reduced pressure drying method in the first or second embodiment. As a modified example, the air supply mechanism 60M (FIG. 17) of the third embodiment may be applied to the fifth embodiment.

According to the fifth embodiment, the top plate portion 13 functions as the cooling member 41, so the number of parts of the reduced pressure drying device 1B is reduced. This allows the size and manufacturing costs of the reduced pressure drying device 1B to be reduced. In addition, the distance between the refrigerant flow path 41a and the cooling surface 40a can be reduced, so the cooling section 40 can cool the cooling surface 40a with higher efficiency.

<6. Sixth embodiment>
21 is a diagram illustrating an example of a vertical cross section of a reduced pressure drying apparatus 1C according to a sixth embodiment. The reduced pressure drying apparatus 1C has a similar configuration to the reduced pressure drying apparatus 1 except for the internal configuration of the cooling section 40.

21, a part of the cooling section 40 of the reduced pressure drying apparatus 1C is located in the internal space 10s of the chamber 10. Specifically, the cooling member 41 is located in the internal space 10s of the chamber 10. The cooling member 41 is provided in the chamber 10 at a position facing the first surface F1 of the substrate 9 supported by the support portion 20. In other words, the cooling member 41 is provided above the substrate 9 supported by the support portion 20. The cooling member 41 is provided in the chamber 10 with its thickness direction aligned in the vertical direction. The cooling member 41 is fixed to the chamber 10 through a fixing portion (not shown). The cooling member 41 may be fixed to the top plate portion 13 of the chamber 10 by a fixing portion such as a screw. In the sixth embodiment, the lower surface of the cooling member 41 corresponds to the cooling surface 40a.

In the example of FIG. 21, the first refrigerant pipe 42 and the second refrigerant pipe 43 pass through the top plate 13, and the refrigerant cooling source 44 is provided outside the chamber 10. The refrigerant cooling source 44 cools the refrigerant while circulating the refrigerant, thereby cooling the cooling member 41. In other words, the cooling surface 40a of the cooling member 41 is cooled.

21, the cooling member 41 has a size larger than the substrate 9 in a plan view. The cooling surface 40a of the cooling member 41 may have a rectangular shape similar to that of the substrate 9 in a plan view. In this case, the long side of the cooling surface 40a is longer than the long side of the substrate 9, and the short side of the cooling surface 40a is longer than the short side of the substrate 9. In this way, the cooling surface 40a can face the entire surface of the first surface F1 of the substrate 9 in the vertical direction. The cooling surface 40a may also have a square shape in a plan view. In this case, one side of the cooling surface 40a may be longer than the short side of the substrate 9. In this way, regardless of the orientation of the substrate 9 placed on the support part 20, the cooling surface 40a is larger than the substrate 9 in a plan view. Therefore, regardless of the orientation of the substrate 9, the cooling surface 40a can face the entire surface of the first surface F1 of the substrate 9.

An example of the flow of the reduced pressure drying method using the reduced pressure drying device 1C is similar to the reduced pressure drying method in the first or second embodiment. As a modified example, the air supply mechanism 60M (FIG. 17) of the third embodiment may be applied to this sixth embodiment.

According to the sixth embodiment, the cooling surface 40a is the underside of a cooling member 41 that is separate from the chamber 10. Therefore, the material of the cooling member 41 having the cooling surface 40a can be selected separately from the specification requirements for the chamber 10. In other words, the selectivity of the material of the cooling member 41 can be improved. In addition, since the cooling surface 40a is the underside of the cooling member 41, the distance between the low-temperature portion of the cooling unit 40 (here, the refrigerant flow path 41a) and the cooling surface 40a can be narrowed. Therefore, the cooling unit 40 can cool the cooling surface 40a with higher efficiency.

<7. Seventh embodiment>
FIG. 22 is a diagram showing an example of a vertical cross section of a reduced pressure drying apparatus 1D according to the seventh embodiment. The reduced pressure drying apparatus 1D has a similar configuration to the reduced pressure drying apparatus 1C (FIG. 21: sixth embodiment) except for the object to be raised and lowered by the first lifting section 100. As shown in FIG. 22, the first lifting section 100 lifts and lowers the cooling section 40. Specifically, the first lifting section 100 lifts and lowers the cooling member 41 of the cooling section 40 between the raised position H11 and the lowered position H12. The lowered position H12 is the position of the cooling member 41 when the distance between the substrate 9 and the cooling surface 40a becomes the first distance. In FIG. 22, the cooling member 41 located at the lowered position H12 is shown by a virtual line. The raised position H11 is the position of the cooling member 41 when the distance between the substrate 9 and the cooling surface 40a becomes the second distance. In other words, the first lifting section 100 raises and lowers the cooling member 41 between a first state in which the distance between the substrate 9 and the cooling surface 40a is a first distance, and a second state in which the distance between the substrate 9 and the cooling surface 40a is a second distance.

As shown in FIG. 22, the support portion 20 is located at the lowered position H2 referred to in the first to sixth embodiments. In other words, the substrate 9 supported by the support portion 20 is located lower than the upper end of the side surface straightening plates 51 and is surrounded by the four side surface straightening plates 51. In the seventh embodiment, the substrate 9 is surrounded by the four side surface straightening plates 51 in both the first state in which the distance between the substrate 9 and the cooling surface 40a is the first distance, and the second state in which the distance between the substrate 9 and the cooling surface 40a is the second distance.

The lowered position H12 may be a position where the cooling surface 40a of the cooling member 41 is lower than the upper end of the side air straightening plate 51. In other words, the cooling member 41 has a size smaller than the space surrounded by the four side air straightening plates 51 in a plan view.

The raised position H11 is a position where the cooling surface 40a of the cooling member 41 is above the upper end of the side straightening plate 51. When the cooling member 41 is in the raised position H11, the distance between the cooling surface 40a and the upper end of the side straightening plate 51 may be, for example, at least twice the first distance, or may be at least five times the first distance. This makes it easier for gas directly above the substrate 9 to flow from the upper end side of the side straightening plate 51 into the space between the side straightening plate 51 and the side wall portion 12 of the chamber 10.

A driving device such as a linear motor or an air cylinder is applied to the first lifting part 100. The main body part 100a of the first lifting part 100 is fixed to an apparatus frame (not shown) outside the chamber 10. The moving part 100b of the first lifting part 100 can move, for example, in the vertical direction relative to the main body part 100a. For example, a rod-shaped member or the like is applied to the moving part 100b. The moving part 100b is positioned, for example, in a state where it is inserted into the through hole 13h of the top plate part 13 of the chamber 10. And, for example, a cooling member 41 is fixed to the lower end part of the moving part 100b. Here, for example, if a bellows or the like is provided between the upper surface of the top plate part 13 and the moving part 100b, the gap between the top plate part 13 and the moving part 100b can be sealed.

An example of the flow of the reduced pressure drying method using the reduced pressure drying device 1D is the same as the reduced pressure drying method in the first or second embodiment. However, in the first gap adjustment process, the first lifting unit 100 lowers the cooling member 41 to the lowered position H12 so that the gap between the substrate 9 and the cooling surface 40a becomes the first gap. In the second gap adjustment process, the first lifting unit 100 raises the cooling member 41 to the raised position H11 so that the gap between the substrate 9 and the cooling surface 40a becomes the second gap. As a modified example, the air supply mechanism 60M (FIG. 17) of the third embodiment may be applied to the seventh embodiment.

According to the seventh embodiment, the cooling member 41 is separate from the chamber 10. Therefore, similar to the sixth embodiment, the selectivity of the material of the cooling member 41 can be improved. Also, since the cooling surface 40a is the lower surface of the cooling member 41, similar to the sixth embodiment, the cooling unit 40 can cool the cooling surface 40a with higher efficiency.

In the seventh embodiment, even in the first state in which the gap between the substrate 9 and the cooling surface 40a is the narrower first gap, the substrate 9 supported by the support portion 20 is surrounded by the four side straightening plates 51. Therefore, even in the first decompression process, the straightening function of the four side straightening plates 51 also acts on the upper space 10s1 between the substrate 9 and the cooling surface 40a. This makes it possible to further suppress the occurrence of uneven drying.

8. Modifications
The present disclosure is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present disclosure.

In each of the above embodiments, the first lifting unit 100 lifts and lowers the support unit 20 or the cooling unit 40, but it may lift and lower both the support unit 20 and the cooling unit 40. In short, the first lifting unit 100 only needs to lift and lower at least one of the support unit 20 and the cooling surface 40a between a first state in which the distance between the substrate 9 supported by the support unit 20 and the cooling surface 40a is a first distance, and a second state in which the distance between the substrate 9 supported by the support unit 20 and the cooling surface 40a is a second distance that is wider than the first distance.

In each of the above embodiments, for example, the chamber 10 has four exhaust ports 16a, 16b, 16c, and 16d, but this is not limited to this. For example, the number of exhaust ports that the chamber 10 has may be any of one to three, and five or more. Also, for example, the individual valves Va, Vb, Vc, and Vd may not be required.

In each of the above embodiments, the reduced pressure drying apparatus 1, 1T, 1A to 1D utilizes the reduced pressure effect to dry the coating film 90 on the substrate 9, but other effects may also be used in combination, for example, a heating effect.

In each of the above embodiments, the side wall portion 12 of the chamber 10 is provided with the loading/unloading port 14 for the substrate 9, but this is not limited thereto. For example, a structure may be adopted in which the four side wall portions 12 and the top plate portion 13 of the chamber 10 form an integrated lid portion, and the lid portion can be separated from the bottom plate portion 11 and retreated upward. In this case, for example, the lid portion may be moved up and down by the opening/closing drive portion 16 or the like. The chamber 10 can be selectively set to a state in which the lid portion contacts the bottom plate portion 11 via a sealing material such as an O-ring to seal the internal space 10s (sealed state), and a state in which the lid portion separates upward from the bottom plate portion 11 to open the internal space 10s (open state). Here, if the chamber 10 is in the open state, the substrate 9 can be loaded into the internal space 10s of the chamber 10 and the substrate 9 can be unloaded from the internal space 10s of the chamber 10. When the chamber 10 is in a closed state, the coating film 90 on the substrate 9 can be dried by reducing pressure by exhausting air from the internal space 10s and supplying air to the internal space 10s.

In each of the above embodiments, for example, the support portion 20 may have various forms. For example, the multiple support plates 21 may be an integrated single support plate 21.

In each of the above embodiments, for example, the bottom surface straightening plate 50 may be omitted, and the side surface straightening plate 51 may be omitted.

In each of the above embodiments, for example, various operations in the reduced pressure drying apparatus 1, 1T, 1A to 1D may be started or ended in response to, for example, a user's action on the input unit 804 or a signal input from an external device to the communication unit 806.

In each of the above embodiments, for example, at least a portion of the functional configuration realized in the control unit 80 may be configured with hardware such as a dedicated electronic circuit.

It goes without saying that all or part of the above embodiments and various modified examples can be combined as appropriate and consistent.

Reference Signs List 1, 1T, 1A to 1D reduced pressure drying apparatus 10 chamber 20 support section 30 reduced pressure mechanism 40 cooling section 40a cooling surface 60 air supply mechanism 63 first buffer section 64 second buffer section 80 control section 9 substrate 90 coating film F1 upper surface V1 to V3 first to third air supply valves

Claims (4)

A reduced pressure drying apparatus for drying a coating film applied on an upper surface of a substrate, comprising:
a chamber for housing the substrate;
a support for supporting the substrate within the chamber;
a cooling unit configured to cool a cooling surface facing the upper surface of the substrate supported by the support unit;
a pressure reducing mechanism that draws gas from the chamber to reduce the pressure within the chamber;
an air supply mechanism that supplies gas into the chamber to increase the pressure in the chamber;
a control unit that controls the air supply mechanism so that after a predetermined amount of gas is supplied from the air supply mechanism into the chamber in a reduced pressure state, the air supply mechanism supplies an amount of gas such that the pressure in the chamber becomes atmospheric pressure;
Equipped with
the pressure reduction mechanism includes a vacuum pump and at least one vacuum valve between the chamber and the vacuum pump;
The control unit is
controlling the at least one vacuum valve so that a gap is opened between the vacuum pump and the chamber when the predetermined amount of gas is supplied;
a vacuum drying apparatus that controls the at least one vacuum valve so that the vacuum pump evacuates the chamber after the predetermined amount of gas has been supplied and before the gas supply mechanism supplies an amount of gas such that the pressure in the chamber becomes atmospheric pressure . the air supply mechanism includes a gas supply source, a first buffer portion between the chamber and the air supply source, a first air supply valve between the chamber and the first buffer portion, and a second air supply valve between the first buffer portion and the air supply source,
the control unit controls the air supply mechanism such that the first air supply valve is switched from a closed state to an open state while the second air supply valve is kept in a closed state in order to supply the predetermined amount of gas.
The reduced pressure drying apparatus according to claim 1 . the air supply mechanism includes a second buffer portion between the second air supply valve and the air supply source, and a third air supply valve between the second buffer portion and the air supply source,
the control unit controls the air intake mechanism so that the first air intake valve is switched from a closed state to an open state while the second air intake valve is kept in a closed state in order to supply the predetermined amount of gas, and then controls the air intake mechanism so that the second air intake valve is switched from a closed state to an open state.
The reduced pressure drying apparatus according to claim 2. A reduced pressure drying method for drying a coating film applied on an upper surface of a substrate, comprising the steps of:
a first step of cooling a cooling surface facing and spaced apart from the upper surface of the substrate supported by a support part in a chamber, and reducing the pressure in the chamber by sucking gas from the chamber, thereby evaporating a solvent from the coating film on the substrate and condensing it on the cooling surface;
a second step of increasing the pressure in the chamber by supplying a predetermined amount of gas into the chamber after the first step, thereby evaporating the solvent on the cooling surface and drying the cooling surface;
a third step of supplying gas in an amount such that the pressure in the chamber becomes atmospheric pressure after the second step;
Equipped with
When the second step is performed, the suction of the gas in the chamber is stopped,
A reduced pressure drying method , wherein after the second step is performed and before the third step is performed, suction of the gas within the chamber is resumed .

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