TWI904001B - Decompression drying device - Google Patents

Abstract

This invention provides a technique for suppressing uneven drying of a coated film. A pressure-reducing drying device (1) includes a chamber (10), a plurality of support pins (22), and a venting section (30). The chamber (10) houses a substrate (9). The plurality of support pins (22) support the substrate (9) from below within the chamber (10). The venting section (30) vents gas from the chamber (10). The plurality of support pins (22) includes one or more first support pins (22a) and one or more second support pins (22b) that are thinner than the first support pins (22a). At least one of the first support pins (22a) supports a peripheral region of the substrate (9) from below. At least one of the second support pins (22b) is a region in which a coated film is formed, which is located in the inner region of the substrate (9) that is more inward than the peripheral region.

Description

Pressure-reducing drying device

This invention relates to a pressure-reducing drying device.

For example, pressure-reducing drying apparatuses are known for reducing the pressure of coating films such as photoresists applied to various substrates. These apparatuses can be used for various substrates, such as glass substrates, ceramic substrates, semiconductor wafers, electronic component substrates, or printed circuit boards used for forming various components. They can be used for various components, such as semiconductor devices, display panels, solar cell panels, magnetic disks, or optical disks. For display panels, they can be used for liquid crystal display panels, electroluminescence (EL) display panels, plasma display panels, or field emission displays.

When drying a coated film using a pressure-reducing drying device, for example, with multiple pins supporting the substrate within the chamber, air is vented from the chamber using a vacuum pump through an exhaust port at the bottom of the chamber. Then, for example, when the vacuum level reaches a predetermined value, the venting from the chamber is stopped, and the chamber is restored to atmospheric pressure by supplying gas into the chamber. For example, inert gases such as nitrogen or air can be used.

Furthermore, in pressure-reducing drying apparatuses, for example, in a coating film formed on the upper surface of a substrate, if the drying speed varies depending on the location, uneven drying (also known as drying inconsistency) may occur corresponding to the different drying speeds. Uneven drying can result in variations in the thickness of the dried coating film, for example.

For example, on a substrate, due to the contact of multiple pins, a temperature difference may arise between the portion supported by the multiple pins and its surrounding portion. Consequently, for example, the drying speed of the coating film may vary depending on the temperature difference caused by the multiple pins. As a result, for example, uneven drying may occur on the coating film corresponding to the arrangement of the multiple pins. Here, for example, during depressurized drying of the coating film, although the temperature of the substrate decreases due to the heat of vaporization generated when the solvent or the like vaporizes from the coating film, the temperature of the multiple pins is difficult to change, whether the heat capacity of the multiple pins is large or the multiple pins are connected to a chamber with a large heat capacity. Therefore, for example, a temperature difference may occur on the substrate corresponding to the arrangement of the multiple pins.

Patent document 1 describes the following: Multiple pins of a support substrate are configured as hollow pins cooled by discharging fluid from their internal space, or as hollow pins cooled by supplying a liquid such as cooling water into their internal space. [Prior Art Documents]

[Patent Documents] [Patent Document 1] Japanese Patent No. 6579773

[Problem to be Solved by the Invention] However, in the pressure-reducing drying device of Patent 1, the device structure becomes complex, leading to a higher cost. Furthermore, in a structure that supplies cooling water to the hollow pin, the potential adverse effects of cooling water leakage on the vacuum state within the chamber should also be considered.

This disclosure is made in view of the aforementioned problem, and its purpose is to provide a technique for suppressing uneven drying of coated films. [Technical Means for Solving the Problem]

The first embodiment is a pressure-reducing drying device for drying a coating film formed on the upper surface of a substrate. The pressure-reducing drying device includes: a chamber for housing the substrate; a plurality of support pins for supporting the substrate from below within the chamber; and a vent for discharging gas from the chamber. The plurality of support pins includes one or more first support pins and one or more second support pins that are thinner than the first support pins. At least one of the first support pins supports a peripheral region of the substrate from below, and at least one of the second support pins supports an inner region of the substrate, which is further inside than the peripheral region, where the coating film is formed.

According to the first type of depressurized drying device, in the second type, the inner region of the substrate is supported only by the second support pin.

According to the first type of pressure-reducing drying device, in the third type, at least one of the first support pins supports the area outside the area where the coating film is formed in the inner region of the substrate.

According to any one of the first to third forms of the depressurized drying device, in the fourth form, the contact area between the first support pin and the substrate is larger than the contact area between the second support pin and the substrate.

According to any one of the first to fourth forms of the depressurized drying device, in the fifth form, the spacing between the first support pins is wider than the spacing between the second support pins.

According to any one of the first to fifth forms of the depressurized drying device, in the sixth form, the thermal conductivity of the second support pin is less than 0.12 W/m·K.

According to any of the first to sixth embodiments of the pressure-reducing drying apparatus, in the seventh embodiment, the second support pin is formed of porous resin. [Effects of the Invention]

In the first configuration, at least one of the second support pins supports an area (hereinafter referred to as the first region) on the inner side of the substrate from which a coating film is formed. Because the second support pins are thin, the amount of rising airflow generated around the second support pins under depressurization of the chamber is small. Therefore, even if gas rises along the second support pins via the rising airflow and is locally supplied to the lower surface of the first region of the substrate, it is difficult to cause deviations in the temperature distribution within the first region. Thus, uneven drying of the coating film on the first region can be suppressed.

With the second form, even if the number, shape, and position of the areas where the coating film is formed change in the inner region, the area can be supported by the second support pin.

The third form provides more robust support for the substrate.

The fourth form can suppress the horizontal offset of the substrate relative to the first support pin. On the other hand, it can reduce the amount of heat movement between the second support pin and the substrate, and further suppress uneven drying of the coating film.

The fifth configuration reduces the number of first support pins, thus reducing the manufacturing cost of the pressure-reducing dryer. Additionally, it reduces the time required for replacing the support pins.

The sixth and seventh forms can reduce the amount of heat movement between the second support pin and the substrate, and further suppress uneven drying of the coating film.

The following description, with reference to the accompanying drawings, illustrates one embodiment and various modifications of this disclosure. In the drawings, parts with the same structure and function are labeled with the same symbols, and repeated descriptions are omitted in the following explanation. The drawings are schematic only, and the dimensions and positional relationships of the various structures in each drawing are not accurately depicted. Furthermore, in this specification, the downward direction represents the direction of gravity, and the upward direction represents the direction opposite to gravity.

<1. Structure of the Pressure-Reduced Drying Device> Figure 1 is a schematic diagram showing an example of a longitudinal section of a pressure-reduced drying device 1 according to one embodiment. Figure 2 is a schematic diagram showing an example of a transverse section of a pressure-reduced drying device 1 according to one embodiment. Figure 3 is a schematic diagram showing an example of a longitudinal section of a pressure-reduced drying device 1 according to one embodiment. The longitudinal sections of Figure 1 and Figure 3 show the structure of the pressure-reduced drying device 1 when viewed from directions that differ by approximately 90 degrees. In Figure 3, to avoid complicating the figures, for convenience, the structures related to the exhaust section 30, the air supply section 60, the pressure gauge 70, and the control section 80, which will be described later, are omitted. The pressure-reducing drying apparatus 1 is an apparatus for drying the coating film 90 (see Figure 5) formed on the upper surface of the substrate 9.

For the substrate 9, a glass substrate, semiconductor wafer, or ceramic substrate can be used, for example. The substrate 9 is, for example, a flat substrate having a first surface F1 (see Figures 4 and 5) as a first main surface and a second surface F2 (see Figure 5) as a second main surface opposite to the first surface F1. For example, in the pressure-reducing drying apparatus 1, the first surface F1 of the substrate 9 is provided as the upper surface of the substrate 9, and the second surface F2 of the substrate 9 is provided as the lower surface of the substrate 9. Here, it is appropriate to give a specific example of using a rectangular glass substrate for the substrate 9 for explanation. On the first surface F1 of the substrate 9, for example, a coating film 90 is partially formed by pre-coating a treatment liquid containing organic materials and solvent. The coating of the treatment liquid is performed, for example, by a slit coating machine or an inkjet printer. For the processing liquid, a coating liquid containing a polyimide precursor and a solvent (also known as a polyimide (PI) liquid) or an anti-corrosion liquid can be used. For the polyimide precursor, polyamide acid (polyyamic acid) can be used, for example. For the solvent, NMP (N-methyl-2-pyrrolidone) can be used, for example. Alternatively, for example, in the case where the pressure-reduced drying apparatus 1 is used in the manufacturing process of an organic EL display, the coating film 90 can be dried in the pressure-reduced drying apparatus 1 to become a hole injection layer, hole transport layer, or light-emitting layer of the organic EL display panel.

Figure 4 is a perspective view showing an example of substrate 9. Figure 5 is a view showing an example of a longitudinal cross-section of a portion of substrate 9. As shown in Figure 4, substrate 9, for example, has a rectangular shape with different lengths in both the longitudinal and transverse directions when viewed from above. Multiple areas (also called forming areas and coating areas) A1 for forming components, etc., are arranged on substrate 9. In the example of Figure 4, when viewed from above, four rectangular coating areas A1 are arranged in a matrix of two rows and two columns on substrate 9. However, the shape, number, and arrangement of the coating areas A1 are not limited to the example described. In the coating step prior to the pressure-reducing drying step of the pressure-reducing drying device 1, the coating film 90 is formed on the upper surface of each coating area A1 according to a desired pattern using a narrow-slit coating machine or an inkjet printer, etc. The desired pattern may be, for example, a circuit pattern. Here, for example, as shown in FIG5, the first surface F1, which is the upper surface of each coating area A1, has an area covered by the coating film 90 (also called the covered area) A3 and an exposed area not covered by the coating film 90 (also called the exposed area) A4. Furthermore, the area surrounding the coating area A1 in the substrate 9 and the area between adjacent coating areas A1 become the area where the coating film 90 is not formed on the first surface F1, which is the upper surface (also called the non-coated area) A2. The non-coated area A2 is also the exposed area (exposed area) A4 that is not covered by the coating film 90.

In the example shown in Figure 4, the peripheral region B1 and the inner region B2 of the substrate 9 are also illustrated. The peripheral region B1 of the substrate 9 is a frame-shaped area extending inward from the outer periphery (i.e., side surface) 9op of the substrate 9 towards the interior with a predetermined width. The predetermined width is, for example, about 100 mm or less. Here, the peripheral region B1 of the substrate 9 is equivalent to a part of the uncoated region A2. That is, no element is formed on the upper surface of the peripheral region B1 of the substrate 9, and no coating film 90 is formed here either. The inner region B2 of the substrate 9 is a region in the substrate 9 that is further inward than the peripheral region B1. The boundary B3 between the peripheral region B1 and the inner region B2 of the substrate 9 has, for example, a rectangular shape. Here, the inner region B2 of the substrate 9 includes multiple coated regions A1, and the region between the multiple coated regions A1 (in Figure 4, it is a cross-shaped uncoated region A2). The inner region B2, for example, has a rectangular shape when viewed from above.

<<Overview of the Structure of the Pressure-Reduced Drying Device>> First, the structure of the pressure-reduced drying device 1 will be summarized. As shown in Figures 1 and 2, the pressure-reduced drying device 1 includes, for example, a chamber 10, a support portion 20, and an exhaust portion 30. The chamber 10 is used to house the substrate 9. The support portion 20 is disposed within the chamber 10 and supports the substrate 9 in a horizontal position. Here, "horizontal position" refers to the position of the substrate 9 along the vertical direction in the thickness direction. The exhaust portion 30 discharges the gas inside the chamber 10 to the outside, causing a decrease in the air pressure inside the chamber 10. Due to the decrease in air pressure, the solvent in the coated film 90 evaporates, and the coated film 90 dries.

In the examples shown in Figures 1 and 2, the pressure-reducing drying device 1 includes: a lifting unit 100, an air supply unit 60, a control unit 80, a bottom rectifier plate 40, a side rectifier plate 50, and a pressure gauge 70. The lifting unit 100 raises and lowers the support unit 20. As a result, the substrate 9 supported by the support unit 20 also rises and falls within the chamber 10. The air supply unit 60 supplies gas into the chamber 10. As a result, the air pressure within the chamber 10 can be restored to atmospheric pressure. The bottom rectifier plate 40 and the side rectifier plate 50 are disposed within the chamber 10 and adjust the airflow within the chamber 10. The pressure gauge 70 measures the air pressure within the chamber 10 and outputs an electrical signal indicating its measurement result to the control unit 80. The control unit 80 controls various structures of the pressure-reducing drying device 1. For example, the control unit 80 controls the exhaust unit 30 based on the air pressure measured by the pressure gauge 70, thereby adjusting the air pressure in the chamber 10 to the target air pressure.

Next, a detailed example of the structure of the pressure-reducing dryer 1 will be described.

<<Cavity 10>> Cavity 10 is the portion used to house the substrate 9. A pressure-resistant container having an internal space 10s for housing the substrate 9 can be used for chamber 10. Chamber 10 is, for example, fixed to a device frame (not shown). The shape of chamber 10 is, for example, a flat cuboid. Chamber 10 has, for example, a generally square base plate 11, four side wall portions 12, and a generally square top plate 13. The four side wall portions 12 connect, for example, the four ends of the base plate 11 to the four ends of the top plate 13 in the vertical direction. For example, one of the four side wall portions 12 is provided with an inlet/outlet 14 and a gate portion (also called a valve) 15 for opening and closing the inlet/outlet 14. The gate portion 15 is connected to or attached to the opening/closing drive portion 16, for example. In Figure 3, the opening/closing drive portion 16 is shown conceptually to avoid complexity. The opening/closing drive portion 16 can be, for example, driven by a cylinder or other similar mechanism. Here, for example, through the operation of the opening/closing drive portion 16, the gate portion 15 can move between a position where the inlet/outlet 14 is closed (also called the closed position) and a position where the inlet/outlet 14 is open (also called the 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 moved into the internal space 10s of the chamber 10 and the substrate 9 can be moved out of the internal space 10s of the chamber 10 via the inlet/outlet 14.

<<Supporting Part 20>> Supporting part 20 is the portion that supports the substrate 9 from below within the chamber 10. For example, supporting part 20 is located in the internal space 10s of chamber 10 and can support the substrate 9 housed in the internal space 10s of chamber 10 from below. Supporting part 20, for example, has multiple supporting plates 21 and multiple supporting pins 22. The multiple supporting plates 21 are arranged at intervals in the horizontal direction, for example. Multiple supporting pins 22 are vertically provided on the upper surface of each supporting plate 21. The multiple supporting plates 21 form the base of supporting part 20. The substrate 9 is disposed, for example, above a plurality of support plates 21, and the upper ends of a plurality of support pins 22 contact a second surface F2, which serves as the lower surface of the substrate 9, thereby supporting the substrate 9 in a horizontal position.

Multiple support pins 22 may include, for example, one or more first support pins 22a and one or more second support pins 22b. In other words, the support portion 20 includes first support pins 22a and second support pins 22b that support the substrate 9 from below. As shown in FIG3, the first support pins 22a and second support pins 22b have a rod-like shape that is elongated in the vertical direction, and the first support pin 22a is thicker than the second support pin 22b.

Figure 6 is a front view of an example of the appearance of the first support pin 22a, and Figure 7 is a front view of an example of the appearance of the second support pin 22b.

In the example of Figure 6, the first support pin 22a is vertically disposed on the upper surface of the first base portion 26a. That is, the first support pin 22a extends upward from the upper surface of the first base portion 26a. The first base portion 26a is wider than the first support pin 22a. In the example of Figure 6, a first external thread portion 27a is provided on the lower surface of the first base portion 26a. The first external thread portion 27a has a columnar shape extending downward from the lower surface of the first base portion 26a, and thread teeth are formed on its side. The first support pin 22a is mounted on the upper surface of the support plate 21 by the thread action generated by the first external thread portion 27a. That is, the first external thread portion 27a is engaged with the internal thread portion (not shown) formed on the upper surface of the support plate 21 by the thread action, thereby the first support pin 22a is installed on the upper surface of the support plate 21.

The pin structure, including the first support pin 22a, the first base portion 26a, and the first external thread portion 27a, can be integrally formed from the same material, or it can be formed by combining multiple components. Furthermore, if the entire pin structure is understood as the first support pin 22a, then the portion above the upper surface of the first base portion 26a can be understood as the first pin body portion.

In the example of Figure 6, the first support pin 22a includes a first abutment portion 23a and a first columnar portion 25a. The first columnar portion 25a has a columnar shape extending in the vertical direction and is erected on the upper surface of the first base portion 26a. That is, the first columnar portion 25a extends upward from the upper surface of the first base portion 26a. The first columnar portion 25a has, for example, a cylindrical shape. In this case, the shape of the first columnar portion 25a in a horizontal cross-section orthogonal to the vertical direction is circular. For example, the first columnar portion 25a extends in the vertical direction with a uniform width. The width (here, the diameter) of the first columnar portion 25a is, for example, set to 1 mm or more, and as a specific example, is set to about 3 mm.

The first abutment portion 23a is disposed on the upper end face of the first columnar portion 25a. The first abutment portion 23a has, for example, a tapered shape. As a specific example, the first abutment portion 23a may have a conical shape. Alternatively, the first abutment portion 23a may also have a hemispherical or semi-elliptical shape. In this case, the shape of the horizontal cross-section of the first abutment portion 23a is also circular. The width (here, the diameter) of this first abutment portion 23a also decreases as it faces upward. The width (here, the diameter) of the lower end of the first abutment portion 23a is, for example, equal to the width (here, the diameter) of the first columnar portion 25a, and is, for example, set to 1 mm or more, and as a more specific example, set to about 3 mm. The upper end (i.e., the apex) of the first contact portion 23a abuts against the second surface F2 of the substrate 9.

As described above, in the example of Figure 6, the first support pin 22a has a rod-shaped form in which its width (here, diameter) decreases monotonically without increasing as it faces upward. In the example of Figure 6, the width of the first support pin 22a is constant in the first columnar portion 25a regardless of the vertical direction, and decreases monotonically as it faces upward in the first abutment portion 23a.

For the material of the first support pin 22a, resin materials such as polyether ether ketone (PEEK) or polyimide (PI) can be used. For example, by appropriately adjusting the friction of the resin material, the first support pin 22a can support the substrate 9 from below using the friction between the upper end of the first support pin 22a and the second surface F2 of the substrate 9, so that the substrate 9 does not shift in the horizontal direction. The first support pin 22a is, for example, a solid material.

Next, an example of the lengths of the first abutment portion 23a and the first columnar portion 25a in the vertical direction will be explained. In the example of FIG. 6, the length of the first abutment portion 23a is very short compared to the length of the first columnar portion 25a. That is, the first columnar portion 25a is the longest. In other words, the first columnar portion 25a occupies the largest proportion of the entire first support pin 22a in the vertical direction. Therefore, the thickness of the first support pin 22a can be represented by the thickness of the first columnar portion 25a. That is, the width (here, the diameter) of the first columnar portion 25a mainly represents the thickness of the first support pin 22a.

In the example of Figure 7, the second support pin 22b is vertically disposed on the upper surface of the second base portion 26b. That is, the second support pin 22b extends upward from the upper surface of the second base portion 26b. The second base portion 26b is wider than the second support pin 22b. In the example of Figure 7, a second external thread portion 27b is provided on the lower surface of the second base portion 26b. The second external thread portion 27b has a columnar shape extending downward from the lower surface of the second base portion 26b, and thread teeth are formed on its side. The second support pin 22b is mounted to the support plate 21 by the thread action of the second external thread portion 27b. The pin structure, including the second support pin 22b, the second base portion 26b, and the second external thread portion 27b, can be integrally formed from the same material, or it can be formed by combining multiple components. Furthermore, if the entire pin structure is understood as the second support pin 22b, then the portion above the upper surface of the second base portion 26b can be understood as the second pin body portion.

In the example of Figure 7, the second support pin 22b includes a second abutment portion 23b and a second columnar portion 25b. The second columnar portion 25b has a columnar shape extending in the vertical direction and is erected on the upper surface of the second base portion 26b. That is, the second columnar portion 25b extends upward from the upper surface of the second base portion 26b. The second columnar portion 25b has, for example, a cylindrical shape. In this case, the horizontal cross-section of the second columnar portion 25b is circular. The second columnar portion 25b extends in the vertical direction with a uniform width, for example. The width (here, the diameter) of the second columnar portion 25b is, for example, set to 0.6 mm or more, and more specifically, set to about 1 mm.

The second abutment portion 23b is disposed on the upper end face of the second columnar portion 25b. The second abutment portion 23b has, for example, a tapered shape. As a specific example, the second abutment portion 23b may also have a conical shape. Alternatively, the second abutment portion 23b may have a hemispherical or semi-elliptical shape. In this case, the horizontal cross-section of the second abutment portion 23b is also circular. The width (here, diameter) of this second abutment portion 23b also decreases as it faces upward. The width (here, diameter) of the lower end of the second abutment portion 23b is, for example, equal to the width (here, diameter) of the second columnar portion 25b, and is, for example, set to 0.6 mm or more, and as a more specific example, is set to about 1 mm. The upper end (i.e., the apex) of the second contact portion 23b abuts against the second surface F2 of the substrate 9.

As described above, in the example of Figure 7, the second support pin 22b has a rod-shaped form in which its width (here, diameter) decreases monotonically without increasing as it faces upward. In the example of Figure 7, the width of the second support pin 22b is constant in the second columnar portion 25b regardless of the vertical direction, and decreases monotonically as it faces upward in the second abutment portion 23b.

For the material of the second support pin 22b, for example, the same resin material as the first support pin 22a, such as polyetheretherketone or polyimide can be used. The second support pin 22b is, for example, a solid material.

Next, the lengths of the second abutment portion 23b and the second columnar portion 25b in the vertical direction will be explained. In the example of FIG. 7, the length of the second abutment portion 23b is very short compared to the length of the second columnar portion 25b. That is, the second columnar portion 25b occupies the largest proportion of the overall length of the second support pin 22b in the vertical direction. Therefore, the thickness of the second support pin 22b can be represented by the thickness of the second columnar portion 25b. That is, the width (here, the diameter) of the second columnar portion 25b mainly represents the thickness of the second support pin 22b.

As can be understood from the comparison in Figures 6 and 7, the first support pin 22a is thicker than the second support pin 22b. Here, the first columnar portion 25a is thicker than the second columnar portion 25b. The difference between the width (here, diameter) of the first columnar portion 25a and the width (here, diameter) of the second columnar portion 25b can be, for example, 0.5 mm or more, 1 mm or more, or 2 mm or more.

Here, a further comparison of the widths of the first support pin 22a and the second support pin 22b in the same horizontal cross-section is examined. As shown in Figures 6 and 7, in any horizontal cross-section along the vertical direction of the first support pin 22a and the second support pin 22b, the width of the first support pin 22a can be greater than the width of the second support pin 22b. For example, the upper part of the first abutment portion 23a of the first support pin 22a and the second abutment portion 23b of the second support pin 22b can have the same shape. According to the shape, the width of the upper part of the first abutment portion 23a in the horizontal cross-section is equal to the width of the second abutment portion 23b. On the other hand, the width of the lower part of the first abutment portion 23a increases further downwards, so in the same horizontal cross-section, the width of the lower part of the first abutment portion 23a of the first support pin 22a is greater than the width of the second columnar portion 25b of the second support pin 22b. Furthermore, the width of the first columnar portion 25a is also greater than the width of the second columnar portion 25b in the same horizontal cross-section. Based on this shape, in any horizontal cross-section, the first support pin 22a and the second support pin 22b are of the same thickness, or the first support pin 22a is thicker than the second support pin 22b.

Furthermore, the comparison of the thickness of the first support pin 22a and the second support pin 22b can also be defined, for example, by comparing the first full circumference of the profile corresponding to the side of the first support pin 22a and the second full circumference of the profile corresponding to the side of the second support pin 22b in the same horizontal cross-section. In the example described, the horizontal cross-sections of the first support pin 22a and the second support pin 22b are circular, so the full circumference is equivalent to the length of a circle.

Here, when the horizontal profile is moved vertically, the range in the vertical direction where the first full circumference is longer than the second full circumference only needs to account for more than 50% of the vertical length of the first support pin 22a and the second support pin 22b. In this case, it can be said that the first support pin 22a is thicker than the second support pin 22b. The ratio can be, for example, more than 60%, more than 70%, or more than 80%.

Figure 8 is a diagram showing a first example of the positional relationship between the substrate 9 and the first support pin 22a and the second support pin 22b. In Figure 8, on the second surface F2, which is the lower surface of the substrate 9, the position supported by the first support pin 22a is indicated by a white circle, and the position supported by the second support pin 22b is indicated by a black circle. In addition, in Figure 8, the outer edge of the coating area A1 in the substrate 9 and the boundary B3 of the peripheral area B1 and the inner area B2 in the substrate 9 are respectively depicted with double-dotted lines.

As shown in Figure 8, a plurality of first support pins 22a support the peripheral region B1 of the substrate 9. That is, the upper ends of these first support pins 22a contact the lower surface of the peripheral region B1 of the substrate 9. The peripheral region B1 of the substrate 9 has a rectangular frame shape in plan view, and therefore these first support pins 22a are also arranged along the entire circumference of the rectangular frame. In the example of Figure 8, no coating film 90 is formed on the upper surface of the peripheral region B1 of the substrate 9. That is, the peripheral region B1 is equivalent to the uncoated region A2. In addition, in the example of Figure 8, the remaining plurality of first support pins 22a are located in the region outside the coated region A1 in the inner region B2 of the substrate 9. That is, the remaining first support pin 22a supports the inner region B2 of the substrate 9, but supports the uncoated region A2 in the inner region B2. In other words, the upper end of the remaining first support pin 22a is in contact with the lower surface of the uncoated region A2 in the inner region B2 of the substrate 9.

On the other hand, multiple second support pins 22b support the coating area A1 in the inner region B2 of the substrate 9. That is, the upper ends of the multiple second support pins 22b contact the lower surface of the coating area A1 of the substrate 9. When a patterned coating film 90 is formed in the coating area A1, some of the second support pins 22b can support the covered area A3 in the coating area A1, and the remaining second support pins 22b can support the exposed area A4 in the coating area A1. When the coating film 90 is formed on the entire coating area A1, the entire coating area A1 is equivalent to the covered area A3, therefore all the second support pins 22b support the covered area A3.

As described above, in the example of FIG8, all the second support pins 22b abut against the lower surface of the coated area A1 in the substrate 9, and all the first support pins 22a abut against the lower surface of the uncoated area A2 in the substrate 9.

Figure 9 is a schematic diagram illustrating an example of airflow within chamber 10 under reduced pressure. When the exhaust section 30 discharges the gas from chamber 10, the temperature of the gas within chamber 10 drops sharply due to adiabatic expansion. The temperature of the gas within chamber 10 can drop to, for example, approximately -20 degrees Celsius. On the other hand, the temperature of the object (solid) within chamber 10 also decreases. For example, the temperature of substrate 9 decreases due to the absorption of the heat of vaporization accompanying the evaporation of the solvent from coating film 90 and heat exchange between substrate 9 and the surrounding gas. Additionally, the temperature of support pin 22 decreases, for example, due to heat exchange between support pin 22 and the surrounding gas. However, the temperature drop of these objects is not as large as the temperature drop of the gas produced by adiabatic expansion. For example, the temperature drop of the support pin 22 is only a few degrees (e.g., less than 2 degrees). Therefore, the temperature of the support pin 22 is, for example, around 23 degrees Celsius.

Through heat exchange between the support pin 22 and the gas, the gas is heated around the support pin 22. Therefore, rising airflows Ga and Gb are generated around the first support pin 22a and the second support pin 22b, respectively. The gas rises along the first support pin 22a via the rising airflow Ga, and the gas rises along the second support pin 22b via the rising airflow Gb. Therefore, the gas can be locally supplied to the second surface F2 of the substrate 9 via the rising airflows Ga and Gb. Therefore, the area around the contact portion with the support pin 22 in the substrate 9 (hereinafter referred to as the pin proximity area) is more susceptible to the influence of the rising airflows Ga and Gb than the area away from the pin proximity area (hereinafter referred to as the pin separation area). As a result, the temperature difference between the region near the pin and the region where the pin separates in the substrate 9 becomes larger, and the temperature distribution of the substrate 9 may become uneven.

Furthermore, in this embodiment, the second support pin 22b is thinner than the first support pin 22a. That is, the second full circumference of the second support pin 22b in the horizontal cross-section is shorter than the first full circumference of the first support pin 22a in the same horizontal cross-section. In other words, the surface area of the side of the second support pin 22b is smaller than the surface area of the side of the first support pin 22a. Therefore, the gas surrounding the first support pin 22a exchanges heat with it over a larger surface area, while the gas surrounding the second support pin 22b exchanges heat with it over a smaller surface area. Therefore, the rising airflow Ga is generated over a wider area (i.e., around the thicker first support pin 22a), while the rising airflow Gb is generated over a narrower area (i.e., around the thinner second support pin 22b). Consequently, the amount of rising airflow Gb generated (e.g., volumetric flow rate) is smaller than that generated by rising airflow Ga. In Figure 9, the amounts of rising airflow Ga and rising airflow Gb are schematically represented by the thickness of the arrow lines.

The second support pin 22b abuts against the lower surface of the coating region A1 of the substrate 9. Therefore, gas can be locally supplied to the lower surface of the coating region A1 through the rising airflow Gb around the second support pin 22b. However, the amount of rising airflow Gb is small, and therefore does not significantly hinder the temperature uniformity in the coating region A1. Therefore, compared to a structure using the first support pin 22a as the support pin 22 abutting against the lower surface of the coating region A1, the uniformity of temperature distribution in the coating region A1 of the substrate 9 can be improved. As a result, the coating film 90 can dry more uniformly. In other words, uneven drying in the coating film 90 formed on the upper surface of the substrate 9 can be suppressed.

On the other hand, the first support pin 22a abuts against the lower surface of the uncoated region A2 of the substrate 9. Therefore, gas can be locally supplied to the lower surface of the uncoated region A2 of the substrate 9 via the rising airflow Ga. The amount of the rising airflow Ga is relatively large, so the temperature distribution in the uncoated region A2 may become less uniform compared to the coated region A1. However, in this example, no coating film 90 is formed in the uncoated region A2, so poor drying of the coating film 90 is unlikely.

Furthermore, the first support pin 22a is thicker than the second support pin 22b, and therefore has higher rigidity. Thus, the first support pin 22a can more firmly support the peripheral region B1 of the substrate 9. For comparison, a structure using a thinner second support pin 22b in all support pins 22 (hereinafter referred to as the comparative structure) is examined. In the comparative structure, when an external force is applied to the substrate 9 in the horizontal direction, the substrate 9 can be displaced in the horizontal direction. This is because the thinner the support pin 22, the weaker the support pin 22 is against external forces in the horizontal direction. For example, the support pin 22 can be bent with the base portion as the fixed end. When the substrate 9 is moved in or out, or when the pressure inside the chamber 10 is reduced, an external force with a horizontal component can be applied to the substrate 9, so that the substrate 9 can be displaced in the horizontal direction. Such horizontal displacement of the substrate 9 is not preferred.

In contrast, in this embodiment, the first support pin 22a supporting the peripheral region B1 of the substrate 9 is thicker than the second support pin 22b supporting the coating region A1 in the inner region B2 of the substrate 9. Therefore, the first support pin 22a can provide higher rigidity support to the peripheral region B1 of the substrate 9. Thus, even when an external force with a horizontal component is applied to the substrate 9, the thicker first support pin 22a can effectively suppress horizontal displacement of the substrate 9. Furthermore, if the first support pins 22a are arranged circumferentially along the periphery of the peripheral region B1 of the substrate 9, the peripheral region B1 of the substrate 9 can be supported more firmly, and horizontal displacement of the substrate 9 can be suppressed more effectively.

<<Exhaust Section 30>> Referring to Figure 1, exhaust section 30 is the part that exhausts the gas inside chamber 10. As shown in Figures 1 and 2, four exhaust ports 16a, 16b, 16c, and 16d are provided, for example, in the portion of the bottom plate 11 of chamber 10 facing the substrate 9 in the vertical direction. Exhaust section 30 includes, for example, an exhaust pipe 31, four individual valves Va, Vb, Vc, and Vd, a main valve Ve, and a vacuum pump 32. Exhaust pipe 31 includes, for example, four individual pipes 31a, 31b, 31c, and 31d and one main pipe 31e. For example, one end of individual pipe 31a is connected to exhaust port 16a, one end of individual pipe 31b is connected to exhaust port 16b, one end of individual pipe 31c is connected to exhaust port 16c, and one end of individual pipe 31d is connected to exhaust port 16d. For example, the other ends of the four individual pipes 31a, 31b, 31c, and 31d merge and connect to one end of the main pipe 31e. For example, the other end of the main pipe 31e is connected to vacuum pump 32. For example, individual valve Va is installed in the path of individual pipe 31a, individual valve Vb is installed in the path of individual pipe 31b, individual valve Vc is installed in the path of individual pipe 31c, and individual valve Vd is installed in the path of individual pipe 31d. For example, the main valve Ve is installed on the path of the main piping 31e.

Here, for example, when the inlet/outlet 14 is closed via gate 15, opening at least one of the four individual valves Va, Vb, Vc, and Vd along with the main valve Ve to operate the vacuum pump 32 allows the gas inside chamber 10 to be discharged to the outside of chamber 10 via exhaust pipe 31. This, for example, can cause a decrease in the air pressure inside chamber 10 for a period of time. The four individual valves Va, Vb, Vc, and Vd are, for example, valves used to individually regulate the amount of gas discharged from the four exhaust ports 16a, 16b, 16c, and 16d. For each of the four individual valves Va, Vb, Vc, and Vd, a valve that switches between open and closed states based on commands from the control unit 80 (also called an on/off valve) can be used. The main valve Ve is, for example, a valve used to adjust the total exhaust volume from the four exhaust ports 16a, 16b, 16c, and 16d. For the main valve Ve, a valve that can adjust its opening degree based on commands from the control unit 80 (also called an opening control valve) can be used.

<<Lifting Part 100>> The lifting part 100 is the portion within the chamber 10 that raises and lowers the support part 20. In other words, for example, the lifting part 100 has a mechanism (also called a lifting mechanism) that allows the support part 20 to be raised and lowered. In Figure 1, the lifting part 100 is shown conceptually to avoid complexity. For example, a direct-acting motor or cylinder can be used as a driving device for the lifting part 100. As shown in Figure 3, the lifting part 100 has, for example, a main body 100a and a moving part 100b. The main body 100a is fixed to a device frame (not shown) outside the chamber 10. The moving part 100b can move vertically relative to the main body 100a. For example, a rod-shaped component can be used for the moving part 100b. The movable part 100b exists, for example, with a through hole 11h extending into the base plate part 11 of the chamber 10. Furthermore, a support part 20 is fixed to the upper end of the movable part 100b, for example. Here, for example, if a bellows or the like is provided between the lower surface of the base plate part 11 and the movable part 100b, the gap between the base plate part 11 and the movable part 100b can be sealed. For example, when the support portion 20 has multiple support plates 21, the moving portion 100b has a rod-shaped portion (also called a rod-shaped portion) that is fixed to each support plate 21 and inserted through a through hole 11h to the base plate portion 11, a portion that connects the multiple rod-shaped portions (also called a connecting portion), and a portion that is connected to the connecting portion and can slidably support the main body portion 100a (also called a sliding portion).

Here, for example, when the lifting unit 100 is in operation, the support unit 20 moves up and down in the vertical direction between the lowered position H1 (the position shown by the dotted line in Figures 1 and 3) and the raised position H2 (the position shown by the double-dotted line in Figures 1 and 3), which is higher than the lowered position H1. At this time, for example, multiple support plates 21 can move up and down together.

<<Bottom Rectifier Plate 40>> The bottom rectifyer plate 40 is a plate used to restrict the flow of gas in the internal space 10s when the exhaust section 30 depressurizes the chamber 10. For example, the bottom rectifyer plate 40 is positioned between the base plate 9 supported by the support section 20 and the bottom plate section 11 of the chamber 10. The bottom rectifyer plate 40 is fixed to the bottom plate section 11 of the chamber 10, for example, by a plurality of support pillars (not shown). As shown in FIG2, for example, the bottom rectifyer plate 40 has a square shape when viewed from above. Moreover, for example, the length of each side of the bottom rectifyer plate 40 when viewed from above is longer than either the long side or the short side of the rectangular base plate 9. Therefore, for example, regardless of the orientation of the base plate 9 disposed on the support section 20, the bottom rectifyer plate 40 is larger than the base plate 9 when viewed from above. Furthermore, the bottom rectifier plate 40, for example, has a through hole 40h through which the moving part 100b of the lifting part 100 is inserted. In the through hole 40h, the bottom rectifier plate 40 and the moving part 100b are separated by a very small gap.

<<Side Rectifier Plate 50>> The side rectifier plate 50, together with the bottom rectifier plate 40, is used to restrict the flow of gas in the internal space 10s when the chamber 10 is depressurized by the exhaust section 30. For example, the side rectifier plate 50 is positioned between the base plate 9 supported by the support portion 20 located in the lowered position H1 and the side wall portion 12 of the chamber 10. Here, for example, four side rectifier plates 50 are arranged to surround the base plate 9 supported by the support portion 20. For example, the four side rectifier plates 50 are generally formed as four corner cylindrical rectifier plates surrounding the base plate 9. Additionally, for example, the bottom rectifier plate 40 and the four side rectifier plates 50 are generally formed as bottom cylindrical box-shaped rectifier plates.

Here, for example, when the chamber 10 is depressurized using the exhaust section 30, the gas in the internal space 10s of the chamber 10 is discharged to the outside of the chamber 10 in the order described above through the space between the side rectifier plate 50 and the side wall portion 12, the space between the bottom rectifier plate 40 and the bottom plate portion 11, and the exhaust ports 16a, 16b, 16c, and 16d. Thus, for example, by the gas flowing in the space away from the substrate 9, it is difficult to form an airflow near the substrate 9. Furthermore, it is difficult to generate a concentrated airflow at the periphery of the substrate 9. Therefore, for example, it is possible to suppress uneven drying of the coating film 90 formed on the upper surface of the substrate 9.

Furthermore, here, for example, as shown in Figure 2, a structure is adopted in which the four exhaust ports 16a, 16b, 16c, and 16d are all located on the diagonal 41 of the square-shaped bottom rectifier plate 40 when viewed from above. In this case, for example, through each exhaust port 16a, exhaust port 16b, exhaust port 16c, and exhaust port 16d, a symmetrical airflow relative to the center of the bottom rectifier plate 40 (the intersection of the two diagonals 41) can be formed. Thus, for example, a more uniform airflow can be formed in the internal space 10s of the chamber 10.

<<Gas Supply Unit 60>> The gas supply unit 60 is the part that performs the operation of supplying gas into the chamber 10 (also referred to as gas supply). As shown in FIG. 1, a gas supply port 16f is provided, for example, on the bottom plate portion 11 of the chamber 10. The gas supply port 16f is located, for example, below the bottom rectifier plate 40. The gas supply unit 60 has a gas supply pipe 61 connected to the gas supply port 16f, a gas supply valve Vf, and a gas supply source 62. For example, one end of the gas supply pipe 61 is connected to the gas supply port 16f. For example, the other end of the gas supply pipe 61 is connected to the gas supply source 62. For example, the gas supply valve Vf is provided in the path of the gas supply pipe 61.

Here, for example, when the gas supply valve Vf is opened, gas is supplied from the gas supply source 62 through the gas supply pipe 61 and the gas supply port 16f to the internal space 10s of the chamber 10. This causes the gas pressure inside the chamber 10 to rise. The gas supplied from the gas supply source 62 can be, for example, an inert gas such as nitrogen, or clean, dry air. Clean, dry air can be prepared, for example, by purifying air in the general environment by removing particles and moisture.

<<Pressure Gauge 70>> The pressure gauge 70 is a sensor that measures the air pressure within the internal space 10s of chamber 10. As shown in Figure 1, for example, the pressure gauge 70 is installed in a portion of chamber 10. The pressure gauge 70, for example, can measure the air pressure within the internal space 10s of chamber 10 and output its measurement result to the control unit 80.

<<Control Unit 80>> The control unit 80 is a unit used to control the operation of various parts of the pressure-reducing dryer 1. For example, the control unit 80 can control the exhaust unit 30, the air supply unit 60, and the lifting unit 100. The control unit 80 may include, for example, a computer having a processor 801 such as a central processing unit (CPU), a memory 802 such as random access memory (RAM), 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 performing a process (also called a pressure-reducing drying process) in the pressure-reducing drying apparatus 1 to dry the coating film 90 on the substrate 9 by reducing pressure, as well as various data. The storage unit 803, for example, stores the program 803p and functions as a non-temporary storage medium that can be read by a computer. The control unit 80 reads the program 803p and the data from the storage unit 803 to the memory 802, and performs calculations on the program 803p and the data in the processor 801, thereby controlling the operation of each part of the pressure-reducing drying apparatus 1. Therefore, for example, program 803p can perform the pressure drying process by being executed by the processor 801 included in the control unit 80 within the pressure-reduced drying device 1.

Additionally, the control unit 80 may also be connected to an input unit 804, an output unit 805, a communication unit 806, and a driver 807. The input unit 804 may be a part that inputs various signals to the control unit 80 in response to user actions. The input unit 804 may include, for example, an operation unit that inputs signals corresponding to user operations, a microphone that inputs signals corresponding to the user's voice, and various sensors that input signals corresponding to the user's movement. The output unit 805 may be a part that outputs various information in a user-recognizable manner. The output unit 805 may include, for example, a display unit, a projector, and a speaker. The display unit may also be a touch panel integrated with the input unit 804. The communication unit 806 is, for example, a component that transmits and receives various types of information between itself and an external device such as a server via a wired or wireless communication device. For example, the storage unit 803 may store a program 803p received from an external device via the communication unit 806. The driver 807 is, for example, a component capable of attaching and detaching a removable storage medium 807m such as a disk or optical disc. The driver 807, for example, performs data transfer between the storage medium 807m and the control unit 80 when the storage medium 807m is installed. For example, a storage medium 807m storing program 803p can be installed in the driver 807, and program 803p can be read from the storage medium 807m and stored in the storage unit 803. Here, the storage medium 807m, for example storing program 803p, functions as a non-temporary storage medium that can be read by a computer.

Figure 10 is a block diagram conceptually illustrating the functions implemented in the control unit 80. As shown in Figure 10, the control unit 80 is electrically connected, for example, to the on/off drive unit 16, the lifting unit 100, four individual valves Va, Vb, Vc, Vd, the main valve Ve, the vacuum pump 32, the air supply valve Vf, and the pressure gauge 70. The control unit 80 can, for example, control the operation of each of these units by referring to the measurement value output from the pressure gauge 70.

As conceptually shown in Figure 10, the control unit 80 has, for example, an on/off control unit 81, a lifting control unit 82, a switching control unit 83, an exhaust control unit 84, a pump control unit 85, and an air supply control unit 86 as its functional structure. For example, the on/off control unit 81 controls the operation of the on/off drive unit 16. For example, the lifting control unit 82 controls the operation of the lifting unit 100. For example, the switching control unit 83 individually controls the on/off states of four individual valves Va, Vb, Vc, and Vd. For example, the exhaust control unit 84 controls the on/off state and opening degree of the main valve Ve. 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 on/off state of the air supply valve Vf. The functions of each part of the control unit 80 are realized, for example, by the processor 801 performing calculations according to the program 803p, etc.

<2. Depressurized Drying Process> Next, the depressurized drying process of the substrate 9 using the depressurized drying apparatus 1 will be described. FIG. 11 is a flowchart showing an example of the depressurized drying process of one embodiment. The depressurized drying process is implemented, for example, by executing program 803p in the processor 801 included in the control unit 80. Here, for example, steps S1 to S4 of FIG. 11 are performed in the aforementioned sequence.

When performing depressurized drying using the depressurized drying device 1, for example, firstly, the substrate 9 is moved into the chamber 10 (step S1). At this time, the substrate 9 is in a state where an undried coating film 90 is formed on its upper surface. In step S1, for example, the gate 15 opens the loading/unloading outlet 14 under the control of the control unit 80, and the conveying robot (not shown) moves the substrate 9 into the internal space 10 of the chamber 10 through the loading/unloading outlet 14 while placing the substrate 9 on the fork-shaped robotic arm. At this time, the support 20 is, for example, positioned in the lowered position H1. For example, while inserting a fork-shaped robotic arm between multiple support plates 21 of the support section 20, the transfer robot places the substrate 9 on the support section 20, and then retracts the fork to the outside of the chamber 10. Then, the gate section 15 closes the transfer outlet 14 under the control of the control unit 80. As described above, in step S1, the step of placing the substrate 9 on the multiple support pins 22 arranged in the chamber 10 is performed (also called the placement step).

In step S1, the substrate 9 is supported by a plurality of support pins 22. Specifically, the peripheral region B1 of the substrate 9 is supported by a first support pin 22a, and the coating region A1 in the inner region B2 of the substrate 9 is supported by a second support pin 22b. Additionally, the uncoated region A2 in the inner region B2 of the substrate 9 is supported by the first support pin 22a.

Next, the depressurization drying device 1 discharges the gas from chamber 10 (step S2). Specifically, the control unit 80 depressurizes chamber 10 by discharging the gas from chamber 10 through the venting unit 30. In other words, step S2 involves depressurizing chamber 10 (also known as the venting step). Through this venting step, the pressure inside chamber 10 drops to the target pressure.

In step S2, for example, the control unit 80 can appropriately raise and lower the support unit 20, and can also appropriately control the opening and closing states of each of the multiple individual valves Va, Vb, Vc, and Vd, and can also appropriately control the opening degree of the main valve Ve. For example, in the initial stage of the venting step, the depressurization drying device 1 can slowly vent the gas in the chamber 10 while the support unit 20 is moved to the rising position H2 (first process), and then, after the support unit 20 is moved to the falling position H1, the venting unit 30 rapidly vents the gas in the chamber 10 (second process). Thus, the chamber 10 can be depressurized while suppressing the generation of a strong airflow around the substrate 9 in the chamber 10.

Subsequently, the exhaust section 30 exhausts the gas in chamber 10 in a manner that maintains a target pressure and is approximately constant (third processing). When the pressure reaches the target pressure, the solvent in the coating film 90 boils, and the drying of the coating film 90 proceeds at a higher rate. When the boiling of the coating film 90 ends, the exhaust section 30 can further depressurize the chamber 10 (fourth processing). This allows for more reliable drying of the coating film 90.

Furthermore, due to the exhaust of gas from chamber 10, the temperature of the gas inside chamber 10 drops sharply, and the temperature of each object inside chamber 10 also decreases to some extent. Therefore, as described above, rising airflows Ga and Gb are generated around the first support pin 22a and the second support pin 22b, respectively, within chamber 10. However, the amount of rising airflow Gb generated is smaller than that of rising airflow Ga, resulting in a smaller deviation in the temperature distribution of the coating area A1 of the substrate 9 caused by rising airflow Gb. Therefore, uneven drying caused by deviations in the temperature distribution of the substrate 9 can be suppressed.

Furthermore, during the exhaust step, the control unit 80 may cause uneven drying of the coated film 90 due to the airflow between the upper surface of the substrate 9 and the top plate portion 13. To suppress the generation of such uneven drying, the opening and closing states of the four individual valves Va, Vb, Vc, and Vd may be switched sequentially in each of the first to third processes. For example, the switching control unit 83 may close one of the four individual valves Va, Vb, Vc, and Vd, and open the others. Moreover, the switching control unit 83 may sequentially change the closed individual valve. Specifically, the system sequentially switches between the following states: a first state where one individual valve Va is closed and the other three individual valves Vb, Vc, and Vd are open; a second state where one individual valve Vb is closed and the other three individual valves Va, Vc, and Vd are open; a third state where one individual valve Vc is closed and the other three individual valves Va, Vb, and Vd are open; and a fourth state where one individual valve Vd is closed and the other three individual valves Va, Vb, and Vc are open. In this way, during the venting step, the direction of airflow in the space between the upper surface of the substrate 9 and the top plate portion 13 changes according to the switching of individual valves Va, Vb, Vc, and Vd. Therefore, the coating film 90 on the upper surface of the substrate 9 can be dried more uniformly. On the other hand, in the fourth process, since the solvent evaporation is inactive, all four individual valves Va, Vb, Vc, and Vd can be opened.

Next, the control unit 80 opens the air supply valve Vf. As a result, gas is supplied from the air supply source 62 through the air supply pipe 61 and the air supply port 16f into the internal space 10s of the chamber 10 (step S3). As a result, the air pressure in the chamber 10 rises again to atmospheric pressure.

Then, for example, the substrate 9 is finally removed from the chamber 10 (step S4). In step S4, for example, firstly, the gate 15 opens the inlet/outlet 14 under the control of the control unit 80, and the conveyor robot (not shown) removes the dried substrate 9, which is placed on the support 20, from the chamber 10 to the outside of the chamber 10 through the inlet/outlet 14. Thus, the depressurization drying process of a substrate 9 can be completed.

Thus, the method of drying the coating film 90 formed on the first surface F1, which is the upper surface of the substrate 9, using the pressure-reduced drying device 1 (also known as the pressure-reduced drying method) includes, for example, a placement step and an exhaust step.

As described above, in one embodiment of the depressurized drying apparatus 1, in step S1, a substrate 9 is placed on a first support pin 22a and a second support pin 22b. The first support pin 22a is thicker than the second support pin 22b. In the example of FIG8, several first support pins 22a support the peripheral region B1 of the substrate 9, and the second support pins 22b support the coating region A1 in the inner region B2 of the substrate 9. The thicker first support pins 22a support the peripheral region B1 of the substrate 9, therefore, for example, in the venting step, even if an external force of the horizontal component is applied to the substrate 9 due to the airflow, the horizontal displacement of the substrate 9 can be more reliably suppressed.

On the other hand, the amount of rising airflow Ga generated around the first support pin 22a during the exhaust step is relatively large. Therefore, it can reduce the uniformity of temperature distribution in the peripheral region B1. However, no coating film 90 is formed in the peripheral region B1, so it hardly causes uneven drying.

The second support pin 22b supporting the coating region A1 of the substrate 9 is thinner, thus reducing the amount of rising airflow Gb generated around the second support pin 22b during the venting step. Therefore, the supply of gas to the lower surface of the coating region A1 of the substrate 9 by the rising airflow Gb can be suppressed. Therefore, the deviation in temperature distribution in the coating region A1 can be reduced, and uneven drying of the coating film 90 can be suppressed.

As described above, the pressure-reducing drying apparatus 1 according to one embodiment can simultaneously suppress the horizontal displacement of the substrate 9 and suppress the deviation of the temperature distribution in the coating area A1.

Furthermore, in the example of Figure 8, the uncoated area A2 in the inner region B2 of the substrate 9 is supported by a thick first support pin 22a. Accordingly, the substrate 9 can be supported more firmly.

<<Number of Support Pins>> As described above, the horizontal displacement of the substrate 9 can be suppressed by the thick first support pin 22a. Therefore, regarding the second support pin 22b, the number of the second support pin 22b can be determined by considering only the strength in the bending direction. For example, the bending load Pcr of the support pin 22 can be expressed by the following formula.

[Number 1] ···（1）

Here, E represents Young's modulus, Imin represents the minimum value of the second moment in the cross section, and L represents the length of the support pin 22.

For example, with a diameter of 0.5 mm, a Young's modulus of 4300 MPa, and a length of 30 mm for the support pin 22, the bending load Pcr is approximately 0.29 N. As long as the weight of the substrate 9 applied to each second support pin 22b is below the bending load Pcr, one second support pin 22b is required for every 130 mm to support a substrate 9 with a thickness of 0.5 mm and a specific gravity of ³ g/cm³.

<<Example of Support Pin Arrangement>> In the example shown in Figure 8, the first support pin 22a abuts against the lower surface of the uncoated area A2 of the substrate 9, and the second support pin 22b abuts against the lower surface of the coated area A1 of the substrate 9. Alternatively, the coated area A1 can be described as a component area used to form components; therefore, it can also be said that the first support pin 22a abuts against the lower surface of the non-component area of the substrate 9, and the second support pin 22b abuts against the component area of the substrate 9. However, this is not necessarily the case.

Figure 12 is a diagram showing a second example of the positional relationship between the substrate 9 and the first support pin 22a and the second support pin 22b. In the example of Figure 12, all the first support pins 22a abut against the lower surface of the peripheral region B1 of the substrate 9, and all the second support pins 22b abut against the lower surface of the inner region B2 of the substrate 9. Conversely, all the first support pins 22a do not abut against the lower surface of the inner region B2 of the substrate 9, but are disposed away from the inner region B2 of the substrate 9. Similarly, all the second support pins 22b do not abut against the lower surface of the peripheral region B1 of the substrate 9, but are disposed away from the peripheral region B1 of the substrate 9.

Accordingly, the thicker first support pin 22a is not located directly below the inner region B2 of the substrate 9. Therefore, even if the number, position, and shape of the coating regions A1 in the inner region B2 of the substrate 9 are changed, the coating regions A1 of the substrate 9 are only supported by the thinner second support pin 22b. Therefore, the region in the substrate 9 where the coating film 90 is formed is only supported by the second support pin 22b. Therefore, even if the number, position, and shape of the coating regions A1 are changed, uneven drying of the coating film 90 can be suppressed.

<<Contact Area of Support Pin 22 and Substrate 9>> The relationship between the first contact area between the upper end of the first support pin 22a and the second surface F2 (which is the lower surface of the substrate 9), and the second contact area between the upper end of the second support pin 22b and the second surface F2 of the substrate 9, is not particularly limited. However, the first contact area of the first support pin 22a supporting the peripheral region B1 of the substrate 9 may be larger than the second contact area.

Accordingly, the frictional force between the first support pin 22a and the peripheral region B1 of the substrate 9 can be greater than the frictional force between the second support pin 22b and the substrate 9. Therefore, the thicker first support pin 22a can reduce the horizontal offset of the substrate 9. On the other hand, if the first contact area is large, the amount of heat moving between the first support pin 22a and the substrate 9 is relatively large. However, since these first support pins 22a support the peripheral region B1 of the substrate 9 (i.e., the uncoated region A2), it is less likely to cause deviations in the temperature distribution in the coated region A1 of the substrate 9.

The second contact area between the second support pin 22b and the substrate 9 is smaller than that between the first support pin 22a and the substrate 9, thus reducing the amount of heat moving between the second support pin 22b and the substrate 9. Although the second support pin 22b supports the coating area A1 of the substrate 9, the small amount of heat movement between the second support pin 22b and the substrate 9 suppresses temperature distribution deviations in the coating area A1. Therefore, uneven drying of the coating film 90 can be suppressed.

<<Spacing of Support Pins 22>> Next, the spacing between the first support pins 22a and the spacing between the second support pins 22b will be explained. Figure 13 is a diagram showing a third example of the positional relationship between the substrate 9 and the first and second support pins 22a and 22b. In the example of Figure 13, the spacing between the first support pins 22a is wider than the spacing between the second support pins 22b.

The first support pin 22a is thicker than the second support pin 22b, so even if the distance between the first support pins 22a is set wider than the distance between the second support pins 22b, the substrate 9 can be properly supported. Conversely, the distance between the first support pins 22a can be set wider than the distance between the second support pins 22b to the extent that displacement of the substrate 9 in the horizontal direction can be suppressed.

Accordingly, the number of first support pins 22a can be reduced, thereby reducing the manufacturing cost of the pressure-reducing drying device 1. Furthermore, the upper end of the support pin 22 can wear down due to contact with the substrate 9. That is, the support pin 22 is a consumable item and therefore needs to be replaced; however, the fewer the number of support pins 22, the less time is required for replacement.

<<Material of Support Pin 22>> The second support pin 22b can, for example, be formed of a porous resin. The term "porous resin" here refers to a resin structure containing multiple micropores within its interior. Such porous resins can, for example, be manufactured through foaming processes such as supercritical foaming. Polypropylene can be used as an example of the resin. The average diameter of the micropores formed within the resin can, for example, be several nm or more, or tens of μm or less.

The thermal conductivity of this second support pin 22b is relatively low. This is because the gas inside the pores conducts heat much less readily than the resin, thus hindering heat movement within the second support pin 22b due to the numerous pores. The thermal conductivity of the second support pin 22b can, for example, be below 0.12 W/m·K.

If the thermal conductivity of the second support pin 22b is low, the amount of heat moving between the second support pin 22b and the substrate 9 through the contact area between the second support pin 22b and the inner region B2 of the substrate 9 can be reduced. Therefore, the temperature uniformity of the substrate 9 can be further improved. Therefore, uneven drying of the coating film 90 formed in the coating region A1 of the substrate 9 can be further suppressed.

Furthermore, the second support pin 22b does not need to be formed entirely of porous resin; for example, it is sufficient that at least the second abutment portion 23b of the second support pin 22b is formed of porous resin. For example, the second abutment portion 23b can be formed of porous resin, and the second columnar portion 25b can also be formed of non-porous resin. This reduces the amount of heat moving between the second support pin 22b and the substrate 9. Of course, when the second support pin 22b is entirely formed of porous resin, heat transfer can be further reduced.

The first support pin 22a can also be formed of porous resin in the same way as the second support pin 22b. Accordingly, the amount of heat moving between the first support pin 22a and the substrate 9 through the contact portion between the first support pin 22a and the peripheral region B1 of the substrate 9 can be reduced. Therefore, the deviation in the temperature distribution of the peripheral region B1 of the substrate 9 can be reduced. Furthermore, the temperature difference between the peripheral region B1 and the inner region B2 of the substrate 9 can be reduced, and the heat movement between the peripheral region B1 and the inner region B2 can be reduced. Therefore, an increase in the deviation in the temperature distribution at the end portion of the inner region B2 can be suppressed or avoided.

<3. Variations> This disclosure is not limited to the described embodiment, and various changes and improvements can be made without departing from the spirit of this disclosure.

In this embodiment, at least one of the two or more support pins 22 supporting the peripheral region B1 of the substrate 9 is a first support pin 22a. In other words, some of the two or more support pins 22 supporting the peripheral region B1 of the substrate 9 can be second support pins 22b. In short, the two or more support pins 22 supporting the peripheral region B1 of the substrate 9 can include both first support pins 22a and second support pins 22b. If one or more thick first support pins 22a support the peripheral region B1 of the substrate 9, horizontal displacement of the substrate 9 can be suppressed. Furthermore, it is ideal that at least half of the support pins 22 supporting the peripheral region B1 are first support pins 22a.

Furthermore, it is permissible for at least one of the two or more support pins 22 supporting the coating region A1 of the substrate 9 to be a second support pin 22b. In other words, some of the two or more support pins 22 supporting the coating region A1 of the substrate 9 may also be first support pins 22a. If one or more thinner second support pins 22b support the coating region A1 of the substrate 9, the temperature distribution deviation of the coating region A1 can be reduced compared to a structure in which only the first support pins 22a support the coating region A1. In addition, it is ideal that at least half of the support pins 22 supporting the peripheral region B1 are second support pins 22b.

Alternatively, the coating film 90 can also be formed on the entire surface of the substrate 9 except for the peripheral region B1.

In one embodiment, the lifting part 100 that raises and lowers the support part 20 may not be present. In this case, multiple support pins 22 may also be fixed to a portion of the upper surface of the bottom rectifier plate 40 or the upper surface of the bottom plate 11 or the chamber 10.

In one embodiment, chamber 10 may have four vents 16a, 16b, 16c, and 16d, but is not limited thereto. For example, the number of vents in chamber 10 may be one to three or more. Additionally, individual valves Va, Vb, Vc, and Vd may be omitted.

In one embodiment, the depressurized drying device 1 dries the coating film 90 on the substrate 9 by depressurization, but is not limited thereto. For example, the depressurized drying device 1 may also dry the coating film 90 on the substrate 9 by depressurization and heating.

In one embodiment, a loading/unloading outlet 14 for the substrate 9 is provided on the side wall portion 12 of the chamber 10, but this is not a limitation. For example, a cover portion consisting of the four side wall portions 12 and the top plate portion 13 of the chamber 10 can be used, and the cover portion can be separated from the bottom plate portion 11 and retracted upwards. In this case, for example, the cover portion can also be moved up and down by an opening/closing drive portion 16, etc. Moreover, the chamber 10 can be selectively configured to a state in which the cover portion contacts the bottom plate portion 11 through a sealing material such as an O-ring to seal the internal space 10s (closed state), and a state in which the cover portion separates from the bottom plate portion 11 and opens the internal space 10s (open state). Here, if the chamber 10 is in an open state, the substrate 9 can be moved into the inner space 10s of the chamber 10 and moved out of the inner space 10s of the chamber 10. If the chamber 10 is in a closed state, the coating film 90 on the substrate 9 can be dried by depressurization through exhaust from the inner space 10s and supply of air to the inner space 10s.

In one embodiment, for example, the support portion 20 may have various forms. For example, multiple support plates 21 may also be an integral single support plate 21.

In one embodiment, for example, the bottom rectifier 40 may be absent, or the side rectifier 50 may be absent.

In one embodiment, for example, various actions in the pressure-reducing drying device 1 may start or end in response to user actions on the input unit 804 or signals input to the communication unit 806 from an external device.

In one embodiment, for example, in the control unit 80, at least a portion of the implemented functional structure may also include dedicated electronic circuits or other hardware.

Furthermore, it is of course possible to combine all or part of the embodiments and various modifications that constitute the described embodiment within a non-contradictory scope.

1: Pressure-reducing drying device 9: Base plate 9op: Outer perimeter (side) 10: Chamber 10s: Internal space 11: Bottom plate 11h, 40h: Through holes 12: Side wall 13: Top plate 14: Loading/unloading outlet 15: Gate (gate valve) 16: Opening/closing drive unit 16a, 16b, 16c, 16d: Exhaust port 16f: Air supply port 20: Support unit 21: Support plate 22: Support pin 22a: First support pin 22b: Second support pin 23a: First abutment part 23b: Second abutment part 25a: First columnar section 25b: Second columnar section 26a: First base section 26b: Second base section 27a: First external thread section 27b: Second external thread section 30: Exhaust section 31: Exhaust piping 31a, 31b, 31c, 31d: Individual piping 31e: Main piping 32: Vacuum pump 40: Bottom rectifier plate 41: Diagonal 50: Side rectifier plate 60: Gas supply section 61: Gas supply piping 62: Gas supply source 70: Pressure gauge 80: Control section 81: Opening and closing control section 82: Lifting control section 83: Switching control section 84: Exhaust control section 85: Pump control section 86: Air Supply Control Unit 90: Coating Film 100: Lifting Unit 100a: Main Body 100b: Moving Unit 801: Processor 802: Memory 803: Storage Unit 803p: Computer Program 804: Input Unit 805: Output Unit 806: Communication Unit 807: Driver 807m: Storage Medium A1: Area (Formed Area, Coated Area) A2: Area (Uncoated Area) A3: Area (Covered Area) A4: Area (Exposed Area) B1: Peripheral Area B2: Inner Area B3: Boundary F1: First Surface F2: Second Surface Ga, Gb: Rising Airflow H1: Downward position H2: Upward position S1～S4: Steps Va, Vb, Vc, Vd: Individual valves Ve: Main valve Vf: Gas supply valve

Figure 1 is a longitudinal cross-section of an example of a pressure-reduced drying apparatus according to one embodiment. Figure 2 is a cross-section of an example of a pressure-reduced drying apparatus according to one embodiment. Figure 3 is a longitudinal cross-section of an example of a pressure-reduced drying apparatus according to one embodiment. Figure 4 is a perspective view showing an example of a substrate. Figure 5 is a longitudinal cross-section showing an example of a portion of the substrate. Figure 6 is a front view showing an example of the appearance of a first support pin. Figure 7 is a front view showing an example of the appearance of a second support pin. Figure 8 is a diagram showing a first example of the relationship between the coating area of the substrate and the first and second support pins. Figure 9 is a diagram schematically showing an example of airflow within a chamber under reduced pressure. Figure 10 is a block diagram conceptually illustrating the functions that can be implemented in the control unit. Figure 11 is a flowchart showing an example of the depressurization drying process in one embodiment. Figure 12 is a diagram showing a second example of the relationship between the coating area of the substrate and the first and second support pins. Figure 13 is a diagram showing a third example of the relationship between the coating area of the substrate and the first and second support pins.

1: Pressure-reducing drying device 9: Substrate 10: Chamber 10s: Internal space 11: Bottom plate 11h, 40h: Through holes 12: Side wall 13: Top plate 14: Loading/unloading outlet 15: Gate (gate valve) 16: Opening/closing drive unit 20: Support unit 21: Support plate 22: Support pin 22a: First support pin 22b: Second support pin 40: Bottom rectifier plate 50: Side rectifier plate 100: Lifting unit 100a: Main body 100b: Moving unit H1: Lowering position H2: Rising position

Claims (5)

A pressure-reducing drying apparatus for drying a coating film formed on the upper surface of a substrate, the pressure-reducing drying apparatus comprising: a chamber for housing the substrate; a plurality of support pins for supporting the substrate from below within the chamber; and a vent for discharging gas from the chamber, the plurality of support pins including one or more first support pins and one or more second support pins thinner than the first support pins, at least one of the first support pins supports a peripheral region of the substrate from below, at least one of the second support pins supports an inner region of the substrate, further inward than the peripheral region, where the coating film is formed, the second support pin has a thermal conductivity of 0.12 W/m·K or less. The pressure-reducing drying apparatus as described in claim 1, wherein, the inner region of the substrate is supported only by the second support pin. The pressure-reducing drying apparatus as described in claim 1, wherein, at least one of the first support pins supports an area of the substrate other than the area where the coating film is formed in the inner region. The pressure-reducing drying apparatus as described in claim 1, wherein, the contact area between the first support pin and the substrate is larger than the contact area between the second support pin and the substrate. The pressure-reducing drying apparatus as described in claim 1, wherein, the second support pin is formed of porous resin.