TWI890056B - Decompression drying device - Google Patents

Abstract

The present invention provides a technology for suppressing uneven drying of a coating film. A pressure-reducing drying device (1) includes a chamber (10), a plurality of support pins (22), and an exhaust portion (30). The chamber (10) accommodates a substrate (9). The plurality of support pins (22) support the substrate (9) from below in the chamber (10). The exhaust portion (30) exhausts gas in the chamber (10). The plurality of support pins (22) include one or more first support pins (22a) and one or more second support pins (22b) thinner than the first support pins (22a). At least one of the first support pins (22a) supports a peripheral area of the substrate (9) from below. At least one of the second support pins (22b) supports from below an area of the substrate (9) where a coating film is formed in an inner area that is further inward than a peripheral area.

Description

Pressure reduction drying device

The present invention relates to a pressure reduction drying device.

For example, known pressure-reduction drying devices are used to reduce the pressure of coatings such as photoresists applied to various substrates. Examples of these substrates include glass substrates, ceramic substrates, semiconductor chips, electronic component substrates, and printed circuit boards used to form various components. Examples of these components include semiconductor devices, display panels, solar cell panels, magnetic disks, and optical disks. Examples of these display panels include liquid crystal display panels, organic electroluminescence (EL) display panels, plasma display panels, and field emission displays.

When drying a coated film using a reduced-pressure drying system, for example, with the substrate supported by multiple pins within a chamber, a vacuum pump is used to evacuate the chamber through an exhaust port at the bottom of the chamber. Then, when the vacuum level reaches a specified value, for example, exhaust from the chamber is stopped and gas is supplied to the chamber to return it to atmospheric pressure. The gas used can be, for example, an inert gas such as nitrogen or air.

For example, in a reduced-pressure drying apparatus, if the drying rate of a coating formed on the upper surface of a substrate varies depending on the location, uneven drying (also known as drying unevenness) may occur in response to the varying drying rates. Drying unevenness can result in variations in the thickness of the dried coating, for example.

For example, due to the contact of multiple pins on a substrate, a temperature difference may occur between the portion supported by the pins and the surrounding portion. Consequently, for example, the drying rate of the coating film may vary depending on the temperature difference caused by the pins. As a result, for example, uneven drying may occur across the coating film, corresponding to the arrangement of the pins. For example, during reduced-pressure drying of a coating film, although the substrate temperature drops due to the heat of vaporization generated when solvent, etc., evaporates from the coating film, the temperature of the pins remains relatively stable, regardless of whether the pins have a large heat capacity or are connected to a chamber with a large heat capacity. Therefore, for example, a temperature difference may occur across the substrate, corresponding to the arrangement of the pins.

Patent Document 1 describes the following: The plurality of pins supporting the substrate are hollow pins that are cooled by discharging a fluid from an internal space, or by supplying a liquid such as cooling water into the internal space. [Prior Art Document]

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

[Problem to be Solved by the Invention] However, the reduced-pressure drying device of Patent Document 1 has a complex structure, resulting in an increased cost. Furthermore, for example, in a structure that supplies cooling water to a hollow pin, there is a concern that leakage of cooling water could adversely affect the vacuum condition within the chamber.

This disclosure was developed in response to the aforementioned issues, and its purpose is to provide a technology for suppressing uneven drying of a coating film. [Technical Solution]

The first form is a decompression drying device for drying a coating film formed on the upper surface of a substrate, the decompression drying device including: a chamber for accommodating the substrate; a plurality of support pins for supporting the substrate from below in the chamber; and an exhaust portion for exhausting the gas in 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 supporting a peripheral area of the substrate from below, and at least one of the second support pins supporting an area of the substrate on which the coating film is formed, in an inner area that is further inward than the peripheral area, from below.

According to the first aspect of the reduced pressure drying device, in the second aspect, the inner area of the substrate is supported only by the second supporting pins.

According to the reduced-pressure drying apparatus of the first aspect, in a third aspect, at least another one of the first supporting pins supports an area of the inner area of the substrate other than the area where the coating film is formed.

According to the reduced pressure drying apparatus of any one of the first to third aspects, in a fourth aspect, a contact area between the first support pin and the substrate is larger than a contact area between the second support pin and the substrate.

According to the reduced pressure drying device of any one of the first to fourth aspects, in a fifth aspect, a pitch between the first support pins is wider than a pitch between the second support pins.

According to the reduced pressure drying device of any one of the first to fifth aspects, in a sixth aspect, the thermal conductivity of the second support pin is less than 0.12 W/m·K.

According to the reduced-pressure drying device of any one of the first to sixth aspects, in a seventh aspect, the second support pin is formed of a porous resin. [Effects of the Invention]

In the first configuration, at least one of the second support pins supports the area of the substrate's inner side where the coating film is formed (hereinafter referred to as the first area) from below. Because the second support pins are thin, the amount of upward airflow generated around the second support pins when the chamber is depressurized is small. Therefore, even if gas rises along the second support pins via this upward airflow and is locally supplied to the lower surface of the first area of the substrate, it is unlikely to cause temperature variations in the first area. Consequently, uneven drying of the coating film in the first area can be suppressed.

According to the second aspect, even if the number, shape, and position of the areas where the coating film is formed in the inner region are changed, the areas can be supported by the second supporting pins.

The third form can support the substrate more firmly.

The fourth aspect reduces the amount of horizontal displacement of the substrate relative to the first support pin. Furthermore, it reduces the amount of heat transfer between the second support pin and the substrate, further minimizing uneven drying of the coating film.

The fifth aspect reduces the number of first support pins, thereby reducing the manufacturing cost of the pressure-reducing dryer. Furthermore, the man-hours required to replace the support pins can be reduced.

According to the sixth and seventh aspects, the amount of heat transfer between the second support pin and the substrate can be reduced, and the uneven drying of the coating film can be further suppressed.

The following describes one embodiment of the present disclosure and various variations with reference to the accompanying drawings. In the drawings, components with identical structures and functions are designated with the same reference numerals, and duplicate descriptions are omitted in the following description. The drawings are schematic only, and the dimensions and positional relationships of the various structures in the drawings are not intended to be exact. In this specification, the downward direction refers to the direction of gravity, and the upward direction refers to the direction opposite to gravity.

<1. Structure of the Pressure Reduction Dryer> Figure 1 schematically illustrates an example of a longitudinal cross-section of a pressure reduction dryer 1 according to one embodiment. Figure 2 schematically illustrates an example of a transverse cross-section of the pressure reduction dryer 1 according to one embodiment. Figure 3 schematically illustrates an example of a longitudinal cross-section of the pressure reduction dryer 1 according to one embodiment. The longitudinal cross-sections of Figure 1 and Figure 3 show the structure of the pressure reduction dryer 1 when viewed from directions approximately 90 degrees apart. In Figure 3, to avoid complication, structures related to the exhaust unit 30, air supply unit 60, pressure gauge 70, and control unit 80, described later, are omitted for convenience. The reduced pressure drying device 1 is a device for drying the coating film 90 (see FIG5 ) formed on the upper surface of the substrate 9 .

For example, a glass substrate, a semiconductor wafer, or a ceramic substrate can be used as the substrate 9. The substrate 9 is, for example, a flat plate having a first surface F1 (see Figures 4 and 5 ) serving as a first main surface and a second surface F2 (see Figure 5 ) serving as a second main surface opposite to the first surface F1. For example, in the reduced pressure drying apparatus 1 , the first surface F1 of the substrate 9 is set as the upper surface of the substrate 9, and the second surface F2 of the substrate 9 is set as the lower surface of the substrate 9. Here, a specific example in which a rectangular glass substrate is used as the substrate 9 will be described. A coating film 90 is partially formed on the first surface F1 of the substrate 9, for example, by pre-applying a treatment liquid containing an organic material and a solvent. The treatment liquid is applied, for example, by a slit coater or an inkjet device. The treatment liquid may include, for example, a liquid containing a polyimide precursor and a solvent (also called a polyimide (PI) liquid) or a coating liquid such as an anti-etching agent liquid. For example, the polyimide precursor may include polyamide acid (polyamic acid). For example, NMP (N-methyl-2-pyrrolidone) may be used as the solvent. Furthermore, if the reduced-pressure drying apparatus 1 is used in the manufacturing process of an organic EL display, the coating film 90 may be dried in the reduced-pressure drying apparatus 1 to form a hole injection layer, hole transport layer, or light-emitting layer of the organic EL display panel.

Figure 4 is a perspective view of an example of a substrate 9. Figure 5 is a diagram showing an example of a longitudinal cross-section of a portion of substrate 9. As shown in Figure 4, substrate 9 has, for example, a rectangular shape with varying lengths in both the vertical and horizontal directions when viewed from above. Multiple areas A1 for forming components and the like (also referred to as formed areas and coating areas) are arranged on substrate 9. In the example of Figure 4, four rectangular coating areas A1 are arranged in a matrix of two rows and two columns on substrate 9 when viewed from above. However, the shape, number, and arrangement of coating areas A1 are not limited to this example. In a coating step prior to the reduced-pressure drying step in the reduced-pressure drying apparatus 1, the coating film 90 is formed on the upper surface of each coating area A1 using a slit coater or inkjet device, for example. The desired pattern can be, for example, a circuit pattern. For example, as shown in FIG5 , the first surface F1, serving as the upper surface of each coating area A1, includes an area A3 covered by the coating film 90 (also referred to as a covered area) and an exposed area A4 not covered by the coating film 90 (also referred to as an exposed area). Furthermore, the areas surrounding coated areas A1 and between adjacent coated areas A1 on substrate 9 constitute areas (also referred to as non-coated areas) A2 where coating film 90 is not formed on first surface F1, which serves as the upper surface. Non-coated areas A2 also constitute exposed areas (exposed areas) A4 that are not covered by coating film 90.

In the example of FIG. 4 , a peripheral area B1 and an inner area B2 of the substrate 9 are also shown. The peripheral area B1 of the substrate 9 is a frame-shaped area extending inward from the outer periphery (i.e., the side surface) 9op of the substrate 9 to a predetermined width. The predetermined width is, for example, approximately 100 mm or less. Here, the peripheral area B1 of the substrate 9 corresponds to a portion of the non-coated area A2. In other words, no components are formed on the upper surface of the peripheral area B1 of the substrate 9, and the coating film 90 is not formed here. The inner area B2 of the substrate 9 is an area of the substrate 9 that is further inward than the peripheral area B1. The boundary B3 between the peripheral area B1 and the inner area B2 of the substrate 9 has, for example, a rectangular shape. Here, the inner area B2 of the substrate 9 includes a plurality of coating areas A1 and areas between the coating areas A1 (in FIG. 4 , cross-shaped non-coating areas A2). The inner area B2 has, for example, a rectangular shape in a plan view.

<<Overview of the Structure of the Reduced-Pressure Drying Apparatus>> First, the structure of the reduced-pressure drying apparatus 1 will be briefly described. As shown in Figures 1 and 2, the reduced-pressure drying apparatus 1 includes, for example, a chamber 10, a support unit 20, and an exhaust unit 30. The chamber 10 houses the substrate 9. The support unit 20 is disposed within the chamber 10 and supports the substrate 9 in a horizontal position. The horizontal position here refers to a position in which the thickness of the substrate 9 is oriented vertically. The exhaust unit 30 exhausts the gas within the chamber 10 to the outside, reducing the pressure within the chamber 10. This reduction in pressure evaporates the solvent in the coating film 90, drying the coating film 90.

In addition, in the example of Figures 1 and 2, the pressure reduction drying device 1 includes: a lifting part 100, an air supply part 60, a control part 80, a bottom straightening plate 40, a side straightening plate 50, and a pressure gauge 70. The lifting part 100 lifts and lowers the support part 20. As a result, the substrate 9 supported by the support part 20 is also lifted and lowered in the chamber 10. The air supply part 60 supplies gas into the chamber 10. As a result, the air pressure in the chamber 10 can be restored to atmospheric pressure. The bottom straightening plate 40 and the side straightening plate 50 are arranged in the chamber 10 and adjust the airflow in the chamber 10. The pressure gauge 70 measures the air pressure in the chamber 10 and outputs an electrical signal indicating its measurement result to the control part 80. The control unit 80 controls various components of the reduced pressure drying apparatus 1. For example, the control unit 80 controls the exhaust unit 30 based on the air pressure measured by the pressure gauge 70 to adjust the air pressure in the chamber 10 to a target air pressure.

Next, an example of the detailed configuration of the reduced-pressure drying apparatus 1 will be described.

<<Chamber 10>> The chamber 10 is a portion for accommodating the substrate 9. A pressure-resistant container having an internal space 10s for accommodating the substrate 9 can be used for the chamber 10. The chamber 10 is fixed to, for example, an apparatus frame (not shown). The chamber 10 has, for example, a flat rectangular parallelepiped shape. The chamber 10 has, for example, a generally square bottom plate 11, four side walls 12, and a generally square top plate 13. The four side walls 12 connect, for example, the four end sides of the bottom plate 11 and the four end sides of the top plate 13 in the vertical direction. For example, one of the four side walls 12 is provided with a loading/unloading port 14 and a gate portion (also called a gate valve) 15 for opening and closing the loading/unloading port 14. The gate portion 15 is connected to or coupled to an opening/closing drive portion 16, for example. In Figure 3, the opening/closing drive portion 16 is shown conceptually to avoid complication. A driving mechanism such as a pneumatic cylinder can be employed as the opening/closing drive portion 16. Here, for example, the operation of the opening/closing drive portion 16 allows the gate portion 15 to move between a position closing the loading/unloading port 14 (also referred to as a closed position) and a position opening the loading/unloading port 14 (also referred to as an open position).

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

<<Supporting Unit 20>> The supporting unit 20 supports the substrate 9 from below within the chamber 10. For example, the supporting unit 20 is located within the interior space 10s of the chamber 10 and can support the substrate 9 housed therein from below. The supporting unit 20 includes, for example, a plurality of supporting plates 21 and a plurality of supporting pins 22. The supporting plates 21 are arranged horizontally at intervals. A plurality of supporting pins 22 are vertically disposed on the top surface of each supporting plate 21. The supporting plates 21 serve as the base of the supporting unit 20. The substrate 9 is placed, for example, above a plurality of support plates 21. The upper ends of the plurality of support pins 22 contact the second surface F2, which is the lower surface of the substrate 9. This supports the substrate 9 in a horizontal position.

The plurality of support pins 22 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 the first support pins 22a and the second support pins 22b, each supporting the substrate 9 from below. As shown in Figure 3, the first support pins 22a and the second support pins 22b are vertically elongated rods, with the first support pins 22a being thicker than the second support pins 22b.

FIG6 is a front view showing an example of the appearance of the first supporting pin 22a, and FIG7 is a front view showing an example of the appearance of the second supporting pin 22b.

In the example of Figure 6 , the first support pin 22a is vertically disposed on the upper surface of the first pedestal 26a. That is, the first support pin 22a extends upward from the upper surface of the first pedestal 26a. The first pedestal 26a is formed to be wider than the first support pin 22a. In the example of Figure 6 , a first externally threaded portion 27a is disposed on the lower surface of the first pedestal 26a. The first externally threaded portion 27a has a columnar shape extending downward from the lower surface of the first pedestal 26a and has thread teeth formed on its side surface. The first support pin 22a is attached to the upper surface of the support plate 21 by the threading action generated by the first externally threaded portion 27a. That is, the first external thread portion 27 a is screwed together with an internal thread portion (not shown) formed on the upper surface of the support plate 21 , whereby the first support pin 22 a is attached to the upper surface of the support plate 21 .

The pin structure comprising the first support pin 22a, the first pedestal 26a, and the first externally threaded portion 27a can be integrally formed from the same material, or can be formed by combining multiple components. Furthermore, if the entire pin structure is considered to be the first support pin 22a, the portion above the upper surface of the first pedestal 26a can be considered to be the first pin body.

In the example of FIG6 , 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 vertically arranged on the upper surface of the first pedestal portion 26a. That is, the first columnar portion 25a extends upward from the upper surface of the first pedestal 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 section perpendicular to the vertical direction is circular. For example, the first columnar portion 25a extends in the vertical direction with a constant width. The width (here, the diameter) of the first columnar portion 25a is, for example, set to 1 mm or more, and is set to approximately 3 mm as a specific example.

The first abutting portion 23a is provided on the upper end surface of the first columnar portion 25a. The first abutting portion 23a has, for example, a pyramidal shape. As a specific example, the first abutting portion 23a may have a conical shape. Alternatively, the first abutting portion 23a may also have a hemispherical or semi-elliptical shape. In this case, the shape of the horizontal cross-section of the first abutting portion 23a is also circular. The width (here, the diameter) of such a first abutting portion 23a also decreases upward. The width (here, the diameter) of the lower end of the first abutting 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, is set to about 3 mm. The upper end (ie, the apex) of the first abutting portion 23 a 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-like shape, with its width (here, diameter) decreasing monotonically and non-increasingly as it moves upward. In the example of Figure 6 , the width of the first support pin 22a is constant in the first columnar portion 25a, independent of the vertical direction, and decreases monotonically upward in the first abutting portion 23a.

The first support pins 22a can be made of a resin material such as polyetheretherketone (PEEK) or polyimide (PI). By appropriately adjusting the friction of the resin material, the first support pins 22a can utilize the friction between the upper ends of the first support pins 22a and the second surface F2 of the substrate 9 to support the substrate 9 from below, preventing the substrate 9 from shifting horizontally. The first support pins 22a can be made of, for example, solid material.

Next, we will explain an example of the vertical lengths of the first contact portion 23a and the first columnar portion 25a. In the example shown in Figure 6, the length of the first contact portion 23a is significantly shorter than that of the first columnar portion 25a. In other words, the first columnar portion 25a occupies the largest proportion of the 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. In other words, the width (here, the diameter) of the first columnar portion 25a primarily reflects the thickness of the first support pin 22a.

In the example of Figure 7 , the second support pin 22b is vertically mounted on the upper surface of the second pedestal 26b. That is, the second support pin 22b extends upward from the upper surface of the second pedestal 26b. The second pedestal 26b is formed wider than the second support pin 22b. In the example of Figure 7 , a second externally threaded portion 27b is mounted on the lower surface of the second pedestal 26b. The second externally threaded portion 27b has a columnar shape extending downward from the lower surface of the second pedestal 26b and has threaded teeth formed on its side surface. The second support pin 22b is attached to the support plate 21 through the threading action of the second externally threaded portion 27b. The pin structure comprising the second support pin 22b, the second pedestal 26b, and the second externally threaded portion 27b may be integrally formed from the same material, or may be formed by combining multiple components. Furthermore, if the entire pin structure is considered to be the second support pin 22b, the portion above the upper surface of the second pedestal 26b may be considered to be the second pin body.

In the example of FIG7 , 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 vertically arranged on the upper surface of the second pedestal portion 26b. That is, the second columnar portion 25b extends upward from the upper surface of the second pedestal 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, for example, with a constant width. The width (here, the diameter) of the second columnar portion 25b is, for example, set to 0.6 mm or more, and as a more specific example, is set to approximately 1 mm.

The second abutting portion 23b is provided on the upper end surface of the second columnar portion 25b. The second abutting portion 23b has, for example, a pyramidal shape. As a specific example, the second abutting portion 23b may also have a conical shape. Alternatively, the second abutting portion 23b has a hemispherical or semi-elliptical shape. In this case, the shape of the horizontal cross-section of the second abutting portion 23b is also circular. The width (here, the diameter) of such a second abutting portion 23b also decreases upward. The width (here, the diameter) of the lower end of the second abutting portion 23b is, for example, equal to the width (here, the 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 (ie, the apex) of the second abutting portion 23 b 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-like shape, with its width (here, diameter) decreasing monotonically and non-increasingly as it moves upward. In the example of Figure 7 , the width of the second support pin 22b is constant in the second columnar portion 25b, independent of the vertical direction, and decreases monotonically upward in the second abutting portion 23b.

The second supporting pin 22b may be made of a resin material such as polyetheretherketone or polyimide, similar to the first supporting pin 22a. The second supporting pin 22b may be made of a solid material.

Next, the vertical lengths of the second abutting portion 23b and the second columnar portion 25b will be explained. In the example shown in Figure 7 , the length of the second abutting portion 23b is significantly shorter than that of the second columnar portion 25b. In other words, the second columnar portion 25b occupies the largest proportion of the second support pin 22b's overall vertical length. Therefore, the thickness of the second support pin 22b can be represented by the thickness of the second columnar portion 25b. In other words, the width (here, the diameter) of the second columnar portion 25b primarily reflects the thickness of the second support pin 22b.

As can be understood from a comparison of 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 greater, 1 mm or greater, or 2 mm or greater.

Here, we further examine the comparison between the widths of the first support pin 22a and the second support pin 22b in the same horizontal cross-section. As shown in Figures 6 and 7, the width of the first support pin 22a in any horizontal cross-section can be greater than the width of the second support pin 22b in the entire vertical direction of the first support pin 22a and the second support pin 22b. For example, the upper portion of the first abutting portion 23a of the first support pin 22a and the second abutting portion 23b of the second support pin 22b can have the same shape. Due to these shapes, the width of the upper portion of the first abutting portion 23a and the width of the second abutting portion 23b in the horizontal cross-section are equal. On the other hand, the width of the lower portion of the first abutting portion 23a increases downward. Therefore, in the same horizontal cross-section, the lower portion of the first abutting portion 23a of the first support pin 22a is wider 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 wider than the width of the second columnar portion 25b in the same horizontal cross-section. Due to this shape, in any horizontal cross-section, the first support pin 22a and the second support pin 22b have the same thickness, or are thicker than the second support pin 22b.

Furthermore, the thickness of the first support pin 22a and the second support pin 22b can also be determined by comparing, for example, a first full circumference length corresponding to the side profile of the first support pin 22a and a second full circumference length corresponding to the side profile of the second support pin 22b in the same horizontal cross-section. In this example, the horizontal cross-sections of the first support pin 22a and the second support pin 22b are circular, and therefore the full circumference length corresponds to the length of the circle.

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

Figure 8 shows a first example of the positional relationship between the substrate 9 and the first and second support pins 22a and 22b. In Figure 8, the locations supported by the first support pins 22a on the second surface F2, which serves as the lower surface of the substrate 9, are indicated by white circles, while the locations supported by the second support pins 22b are indicated by black circles. Furthermore, in Figure 8, the outer edge of the coating area A1 on the substrate 9 and the boundaries B3 between the peripheral area B1 and the inner area B2 of the substrate 9 are depicted with double-dotted lines.

As shown in FIG8 , a plurality of first support pins 22a support the peripheral area B1 of the substrate 9. Specifically, the upper ends of these first support pins 22a contact the lower surface of the peripheral area B1 of the substrate 9. The peripheral area B1 of the substrate 9 has a rectangular frame shape when viewed in plan, so these first support pins 22a are also arranged along the entire circumference of the rectangular frame. In the example of FIG8 , the coating film 90 is not formed on the upper surface of the peripheral area B1 of the substrate 9. That is, the peripheral area B1 corresponds to the non-coated area A2. Furthermore, in the example of FIG8 , the remaining plurality of first support pins 22a are located in an area outside the coated area A1 within the inner area B2 of the substrate 9. That is, the remaining first support pins 22a support the inner area B2 of the substrate 9, but also support the non-coated area A2 in the inner area B2. In other words, the upper ends of the remaining first support pins 22a contact the lower surface of the non-coated area A2 in the inner area B2 of the substrate 9.

Meanwhile, the plurality of second support pins 22b support the coating area A1 within the inner area B2 of the substrate 9. Specifically, the upper ends of the plurality of second support pins 22b contact the lower surface of the coating area A1 of the substrate 9. If the coating area A1 is coated with a patterned coating film 90, some of the second support pins 22b can support the covered area A3 within the coating area A1, while the remaining second support pins 22b can support the exposed area A4 within the coating area A1. If the entire coating area A1 is coated with the coating film 90, the entire coating area A1 corresponds to the covered area A3, and therefore all of the second support pins 22b support the covered area A3.

As described above, in the example of FIG. 8 , all the second support pins 22 b abut against the lower surface of the coated area A1 of the substrate 9 , and all the first support pins 22 a abut against the lower surface of the non-coated area A2 of the substrate 9 .

Figure 9 schematically illustrates an example of the airflow within chamber 10 under reduced pressure. When the exhaust unit 30 exhausts the air within chamber 10, the temperature of the air within chamber 10 drops rapidly due to adiabatic expansion. The temperature of the air within chamber 10 can drop to, for example, approximately -20 degrees Celsius. Meanwhile, the temperature of the objects (solids) within chamber 10 also drops. For example, the temperature of substrate 9 drops due to the absorption of the heat of vaporization associated with the evaporation of the solvent in coating film 90 and heat exchange between substrate 9 and the surrounding air. Furthermore, the temperature of support pins 22, for example, drops due to heat exchange between the support pins 22 and the surrounding air. However, the temperature drop of these objects is not as great as the temperature drop of the gas due to 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, about 23 degrees Celsius.

The heat exchange between the support pins 22 and the gas heats the gas around the support pins 22. Consequently, an ascending airflow Ga and an ascending airflow Gb are generated around the first support pin 22a and the second support pin 22b, respectively. The ascending airflow Ga causes the gas to rise along the first support pin 22a, while the ascending airflow Gb causes the gas to rise along the second support pin 22b. Consequently, the ascending airflows Ga and Gb enable gas to be locally supplied to the second surface F2 of the substrate 9. Consequently, the area around the contact point with the support pins 22 on the substrate 9 (hereinafter referred to as the pin-proximate area) is more susceptible to the influence of the ascending airflows Ga and Gb than the area farther from the pin-proximate area (hereinafter referred to as the pin-separated area). As a result, the temperature difference between the area near the pins in the substrate 9 and the area separated from the pins becomes larger, and the temperature distribution of the substrate 9 may become uneven.

In this embodiment, the second support pin 22b is thinner than the first support pin 22a. Specifically, the second full circumference of the second support pin 22b in a horizontal cross-section is shorter than the first full circumference of the first support pin 22a in the horizontal cross-section. In other words, the side surface area of the second support pin 22b is smaller than the side surface area of the first support pin 22a. Therefore, the gas surrounding the first support pin 22a exchanges heat with the first support pin 22a over a larger surface area, while the gas surrounding the second support pin 22b exchanges heat with the second support pin 22b over a smaller surface area. Therefore, the upward airflow Ga is generated over a wider area (i.e., around the thick first support pin 22a), while the upward airflow Gb is generated over a narrower area (i.e., around the thin second support pin 22b). Consequently, the amount of upward airflow Gb generated (e.g., volume flow rate) is smaller than that of the upward airflow Ga. Figure 9 schematically illustrates the amounts of upward airflow Ga and Gb generated by the thickness of the arrows.

The second support pin 22b abuts the lower surface of the coating area A1 of the substrate 9. Therefore, gas can be locally supplied to the lower surface of the coating area A1 through the rising airflow Gb around the second support pin 22b. However, the amount of rising airflow Gb generated is small, so it does not significantly hinder the temperature uniformity in the coating area A1. Therefore, compared with the structure in which the first support pin 22a is used as the support pin 22 abutting the lower surface of the coating area A1, the uniformity of the temperature distribution in the coating area A1 of the substrate 9 can be improved. As a result, the coating film 90 can be dried more evenly. In other words, the occurrence of drying unevenness 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 the lower surface of the non-coated area A2 of the substrate 9. Therefore, the ascending airflow Ga allows gas to be locally supplied to the lower surface of the non-coated area A2 of the substrate 9. The relatively large amount of this ascending airflow Ga may cause the temperature distribution in the non-coated area A2 to become less uniform than in the coated area A1. However, in this example, since the coating film 90 is not formed in the non-coated area A2, there is little chance of poor drying of the coating film 90.

Furthermore, the first support pins 22a are thicker than the second support pins 22b and therefore have a higher rigidity. Therefore, the first support pins 22a can more firmly support the peripheral area B1 of the substrate 9. For comparison, a structure in which all support pins 22 use thin second support pins 22b (hereinafter referred to as the comparison structure) was examined. In this comparison structure, when an external force is applied to the substrate 9 in the horizontal direction, the substrate 9 can displace horizontally. This is because the thinner the support pins 22, the less resistant they are to horizontal external forces. For example, the support pins 22 can bend with the base portion as the fixed end. When the substrate 9 is loaded or unloaded or when the pressure in the chamber 10 is reduced, an external force with a horizontal component can be applied to the substrate 9, causing the substrate 9 to displace horizontally. Such horizontal displacement of the substrate 9 is not preferred.

In contrast, in this embodiment, the first support pins 22a supporting the peripheral area B1 of the substrate 9 are thicker than the second support pins 22b supporting the coated area A1 in the inner area B2 of the substrate 9. Therefore, the first support pins 22a can support the peripheral area B1 of the substrate 9 with greater rigidity. Consequently, even when external forces with a horizontal component are applied to the substrate 9, the thick first support pins 22a effectively suppress horizontal displacement of the substrate 9. Furthermore, by arranging the first support pins 22a along the entire circumference of the peripheral area B1 of the substrate 9, the peripheral area B1 of the substrate 9 can be more firmly supported, and horizontal displacement of the substrate 9 can be more effectively suppressed.

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

Here, for example, when the loading/unloading port 14 is closed by the gate portion 15, at least one of the four individual valves Va, Vb, Vc, and Vd and the main valve Ve are opened to operate the vacuum pump 32. Gas within the chamber 10 is discharged to the exterior of the chamber 10 via the exhaust pipe 31. This, for example, reduces the pressure in the internal space 10s of the chamber 10. The four individual valves Va, Vb, Vc, and Vd are valves used to adjust the amount of gas discharged from the four exhaust ports 16a, 16b, 16c, and 16d, respectively. Each of the four individual valves Va, Vb, Vc, and Vd can be, for example, a valve that switches between an open and closed state based on a command from the control unit 80 (also known as an on-off valve). 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 example, the main valve Ve can be a valve whose opening can be adjusted based on a command from the control unit 80 (also known as an opening control valve).

<<Lifting Unit 100>> The lifting unit 100 is the part that raises and lowers the support unit 20 within the chamber 10. In other words, for example, the lifting unit 100 includes a mechanism (also referred to as a lifting mechanism) that can raise and lower the support unit 20. In Figure 1, the lifting unit 100 is shown conceptually to avoid complication. A drive device such as a linear motor or an air cylinder can be used for the lifting unit 100. As shown in Figure 3, the lifting unit 100 includes, for example, a main body 100a and a movable portion 100b. The main body 100a is fixed to a device frame (not shown) outside the chamber 10, for example. The movable portion 100b can move vertically relative to the main body 100a. For example, a rod-shaped member can be used for the movable portion 100b. The movable portion 100b exists, for example, in a state of being inserted into a through-hole 11h of the bottom plate 11 of the chamber 10. Furthermore, a support portion 20 is fixed to the upper end of the movable portion 100b. For example, by providing a bellows or the like between the lower surface of the bottom plate 11 and the movable portion 100b, the gap between the bottom plate 11 and the movable portion 100b can be sealed. For example, if the support portion 20 includes multiple support plates 21, the movable portion 100b includes a rod-shaped portion (also referred to as a rod portion) fixed to the support plate 21 for each support plate 21 and inserted into the through hole 11h of the bottom plate 11; a portion connecting the multiple rod-shaped portions (also referred to as a connecting portion); and a portion connected to the connecting portion and slidably supported by the main body 100a (also referred to as a sliding portion).

Here, for example, when the lifting unit 100 is operated, the support unit 20 is vertically moved between a lowered position H1 (the position indicated by the dotted line in Figures 1 and 3 ) and an elevated position H2 (the position indicated by the double-dotted line in Figures 1 and 3 ), which is higher than the lowered position H1. In this case, for example, the plurality of support plates 21 can be raised and lowered integrally.

<<Bottom Surface Straightener 40>> The bottom surface straightener 40 is a plate used to restrict the flow of gas within the internal space 10s when the exhaust unit 30 depressurizes the chamber 10. For example, the bottom surface straightener 40 is positioned between the substrate 9 supported by the support unit 20 and the bottom plate 11 of the chamber 10. The bottom surface straightener 40 is secured to the bottom plate 11 of the chamber 10 via, for example, multiple supports (not shown). As shown in Figure 2 , the bottom surface straightener 40 has a square shape when viewed from above. Furthermore, for example, the length of each side of the bottom surface straightener 40 when viewed from above is longer than either the long side or the short side of the rectangular substrate 9. Therefore, regardless of the orientation of the substrate 9 on the support unit 20, the bottom surface straightener 40 appears larger than the substrate 9 when viewed from above. Furthermore, the bottom straightening plate 40 has a through-hole 40h through which the moving portion 100b of the lifting unit 100 is inserted. In the through-hole 40h, the bottom straightening plate 40 and the moving portion 100b are spaced very closely.

<<Side Straighteners 50>> The side straighteners 50, along with the bottom straighteners 40, are used to restrict the flow of gas within the internal space 10s when the exhaust unit 30 depressurizes the chamber 10. For example, the side straighteners 50 are positioned between the substrate 9 supported by the support unit 20 in the lowered position H1 and the sidewall 12 of the chamber 10. For example, four side straighteners 50 are positioned to surround the substrate 9 supported by the support unit 20. For example, the four side straighteners 50 collectively form a rectangular cylindrical straightener surrounding the substrate 9. Alternatively, the bottom straightener 40 and the four side straighteners 50 may collectively form a box-shaped straightener with a cylindrical bottom.

Here, for example, when the exhaust unit 30 depressurizes the interior of the chamber 10, the gas in the internal space 10s of the chamber 10 passes through the space between the side straighteners 50 and the sidewalls 12, the space between the bottom straighteners 40 and the bottom plate 11, and the exhaust ports 16a, 16b, 16c, and 16d in the order described above, and is exhausted to the exterior of the chamber 10. This allows the gas to flow through a space away from the substrate 9, for example, making it difficult for airflow to form near the substrate 9. Furthermore, it also prevents concentrated airflow from forming around the periphery of the substrate 9. This, for example, can suppress the occurrence of uneven drying of the coating film 90 formed on the upper surface of the substrate 9.

Furthermore, as shown in FIG2 , for example, a structure is employed in which the four exhaust ports 16a, 16b, 16c, and 16d are all located on diagonal lines 41 of the square bottom flow plate 40 in a top view. In this case, for example, symmetrical airflows can be formed with respect to the center of the bottom flow plate 40 (the intersection of the two diagonal lines 41) through the exhaust ports 16a, 16b, 16c, and 16d. This allows for a more uniform airflow to be formed within the interior space 10s of the chamber 10, for example.

<<Air Supply Unit 60>> The air supply unit 60 is responsible for supplying gas into the chamber 10 (also referred to as "air supply"). As shown in Figure 1 , the bottom plate 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 straightener 40. The air supply unit 60 includes an air supply pipe 61 connected to the air supply port 16f, an air supply valve Vf, and an air supply source 62. For example, one end of the air supply pipe 61 is connected to the air supply port 16f. For example, the other end of the air supply pipe 61 is connected to the air supply source 62. For example, the air supply valve Vf is provided along the path of the air supply pipe 61.

Here, for example, when the air supply valve Vf is opened, 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. This increases the air pressure within the chamber 10. The gas supplied from the air supply source 62 can be, for example, an inert gas such as nitrogen, or clean dry air. Clean dry air can be prepared by, for example, purifying air from a general environment to remove particles and moisture.

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

<<Control Unit 80>> The control unit 80 controls the operation of various components of the reduced-pressure drying apparatus 1. For example, the control unit 80 controls the exhaust unit 30, the air supply unit 60, and the elevator 100. The control unit 80 includes, 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 drive. The storage unit 803 stores, for example, a computer program (also referred to as a program) 803p and various data for executing a process (also referred to as a decompression drying process) for drying the coating film 90 on the substrate 9 by decompression in the decompression drying apparatus 1. The storage unit 803, for example, stores the program 803p and functions as a non-temporary storage medium readable by a computer. The control unit 80 reads the program 803p and data from the storage unit 803 into the memory 802, and performs computations in accordance with the program 803p and data in the processor 801, thereby controlling the operation of various components of the decompression drying apparatus 1. Therefore, for example, 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 process.

Furthermore, 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 driver 807. The input unit 804, for example, inputs various signals to the control unit 80 in response to user actions, etc. 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 movements. The output unit 805, for example, outputs various information in a manner recognizable to the user. 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, for example, transmits and receives various information with external devices such as servers via wired or wireless communication components. For example, the storage unit 803 may also store a program 803p received from an external device via the communication unit 806. The drive 807, for example, is capable of loading and unloading a removable storage medium 807m, such as a magnetic disk or optical disk. When the storage medium 807m is installed, the drive 807 transfers data between the storage medium 807m and the control unit 80. For example, the storage medium 807m storing the program 803p may be installed in the drive 807, and the program 803p may be read from the storage medium 807m and stored in the storage unit 803. Here, the storage medium 807m, for example, stores the program 803p and functions as a non-temporary storage medium readable by a computer.

FIG10 is a block diagram conceptually illustrating the functions implemented in the control unit 80. As shown in FIG10 , the control unit 80 is electrically connected to, for example, the opening/closing actuator 16, the lifting unit 100, the four individual valves Va, Vb, Vc, and Vd, the main valve Ve, the vacuum pump 32, the air supply valve Vf, and the pressure gauge 70. The control unit 80 can control the operation of each of these components, for example, by referring to the measured values output from the pressure gauge 70.

As conceptually shown in FIG10 , the control unit 80 includes, 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, and an air supply control unit 86 as functional structures implemented. 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 lifting unit 100. For example, the switching control unit 83 controls the opening/closing states of the four individual valves Va, Vb, Vc, and Vd, respectively. For example, the exhaust control unit 84 controls the opening/closing 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 opening/closing state of the air supply valve Vf. The functions of the various components of the control unit 80 are realized by, for example, the processor 801 performing arithmetic processing according to the program 803p and the like.

<2. Reduced Pressure Drying Process> Next, the reduced pressure drying process of substrate 9 using reduced pressure drying apparatus 1 will be described. Figure 11 is a flow chart showing an example of a reduced pressure drying process flow according to one embodiment. This reduced pressure drying process flow is implemented, for example, by executing program 803p in processor 801 included in control unit 80. Here, for example, steps S1 through S4 in Figure 11 are performed in the order described.

When performing a reduced-pressure drying process using the reduced-pressure drying apparatus 1, for example, a substrate 9 is first loaded into the chamber 10 (step S1). At this point, an undried coating film 90 is already formed on the upper surface of the substrate 9. In step S1, for example, the gate portion 15 opens the loading/unloading port 14 under the control of the control unit 80. A transport robot (not shown) simultaneously places the substrate 9 on a fork-shaped manipulator and simultaneously loads the substrate 9 into the chamber 10's interior space via the loading/unloading port 14 for 10 seconds. At this point, the support unit 20 is, for example, positioned at the lowered position H1. The transfer robot, for example, inserts its fork-shaped hand between the plurality of support plates 21 of the support portion 20, places the substrate 9 on the support portion 20, and then retracts the fork outside the chamber 10. The gate portion 15 then closes the loading/unloading port 14 under the control of the control unit 80. As described above, in step S1, the substrate 9 is placed on the plurality of support pins 22 arranged in the chamber 10 (also referred to as a placement step).

In step S1, the substrate 9 is supported by a plurality of support pins 22. Specifically, the peripheral area B1 of the substrate 9 is supported by the first support pins 22a, while the coated area A1 within the inner area B2 of the substrate 9 is supported by the second support pins 22b. Furthermore, the non-coated area A2 within the inner area B2 of the substrate 9 is supported by the first support pins 22a.

Next, the decompression drying apparatus 1 exhausts the gas within the chamber 10 (step S2). Specifically, the control unit 80 instructs the exhaust unit 30 to exhaust the gas within the chamber 10, thereby reducing the pressure within the chamber 10. In other words, in step S2, the decompression step (also called the exhaust step) within the chamber 10 is performed. Through this exhaust step, the pressure within the chamber 10 drops to the target pressure.

In step S2, for example, the control unit 80 may appropriately raise or lower the support unit 20, individually and appropriately control the opening and closing states of the multiple individual valves Va, Vb, Vc, and Vd, or appropriately control the opening degree of the main valve Ve. For example, the decompression drying apparatus 1 may initially exhaust the gas within the chamber 10 while moving the support unit 20 to the raised position H2 (a first process). Subsequently, after the support unit 20 is moved to the lowered position H1, the exhaust unit 30 rapidly exhausts the gas within the chamber 10 (a second process). This allows the pressure within the chamber 10 to be reduced while suppressing the generation of strong airflow around the substrate 9 within the chamber 10.

The exhaust unit 30 then exhausts the gas within the chamber 10 to a target pressure, maintaining a substantially constant pressure (the third process). When the pressure reaches the target pressure, the solvent in the coating film 90 boils away, accelerating the drying of the coating film 90. Once the boiling of the coating film 90 has ceased, the exhaust unit 30 can further reduce the pressure within the chamber 10 (the fourth process). This allows for more reliable drying of the coating film 90.

Furthermore, the exhaust of gas from chamber 10 causes the temperature of the gas within chamber 10 to drop dramatically, and the temperature of the objects within chamber 10 also drops to a certain extent. Therefore, as described above, upward airflows Ga and Gb are generated around the first support pins 22a and the second support pins 22b within chamber 10, respectively. However, the amount of upward airflow Gb generated is smaller than that of upward airflow Ga, so the temperature distribution of coating area A1 of substrate 9 caused by upward airflow Gb is less skewed. Consequently, the occurrence of uneven drying caused by variations in the temperature distribution of substrate 9 can be suppressed.

Furthermore, during the exhaust step, the control unit 80 may cause uneven drying of the coating film 90 due to the airflow between the upper surface of the substrate 9 and the top plate portion 13. To prevent this uneven drying, the open and closed states of the four individual valves Va, Vb, Vc, and Vd may be sequentially switched in each of the first through 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 other individual valves. Furthermore, the switching control unit 83 sequentially changes the closed individual valve. Specifically, the system switches sequentially between a first state in which one individual valve Va is closed and the other three individual valves Vb, Vc, and Vd are opened; a second state in which one individual valve Vb is closed and the other three individual valves Va, Vc, and Vd are opened; a third state in which one individual valve Vc is closed and the other three individual valves Va, Vb, and Vd are opened; and a fourth state in which one individual valve Vd is closed and the other three individual valves Va, Vb, and Vc are opened. In this manner, during the exhaust step, the direction of the airflow in the space formed between the upper surface of the base plate 9 and the top plate portion 13 changes according to the switching of the 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 evaporation of the solvent is not active, all four individual valves Va, Vb, Vc, and Vd can be opened.

Next, the control unit 80 opens the air supply valve Vf. This causes gas to be 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 back to atmospheric pressure.

Then, for example, the substrate 9 is finally unloaded from the chamber 10 (step S4). In step S4, for example, the gate portion 15 first opens the loading/unloading port 14 under the control of the control unit 80. A transport robot (not shown) then unloads the dried substrate 9 placed on the support portion 20 out of the chamber 10 through the loading/unloading port 14 of the chamber 10. This completes the decompression drying process for one substrate 9.

Thus, a method of drying the coating film 90 formed on the first surface F1 serving as the upper surface of the substrate 9 using the reduced pressure drying apparatus 1 (also referred to as a reduced pressure drying method) includes, for example, a placement step and an exhaust step.

As described above, in the reduced-pressure drying apparatus 1 of one embodiment, in step S1, the substrate 9 is placed on the first support pins 22a and the second support pins 22b. The first support pins 22a are thicker than the second support pins 22b. In the example shown in FIG8 , a plurality of the first support pins 22a support the peripheral area B1 of the substrate 9, while the second support pins 22b support the coating area A1 within the inner area B2 of the substrate 9. The thick first support pins 22a support the peripheral area B1 of the substrate 9. Therefore, even if a horizontal component of external force is applied to the substrate 9 by the airflow during the exhaust step, 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, the uniformity of the temperature distribution in the peripheral area B1 can be reduced. However, since the coating film 90 is not formed in the peripheral area B1, there is little chance of uneven drying.

The thin second support pins 22b supporting the coating area A1 of the substrate 9 can reduce the amount of upward airflow Gb generated around the second support pins 22b during the exhaust step. This prevents the upward airflow Gb from supplying gas to the lower surface of the coating area A1 of the substrate 9. This reduces temperature variations in the coating area A1 and prevents uneven drying of the coating film 90.

As described above, according to the reduced pressure drying apparatus 1 of one embodiment, it is possible to achieve both suppression of horizontal displacement of the substrate 9 and suppression of variations in temperature distribution in the coating area A1.

8, the non-coated area A2 in the inner area B2 of the substrate 9 is supported by the thick first support pins 22a. This allows the substrate 9 to be supported more firmly.

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

[Number 1] ···（1）

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

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

<<Example of Support Pin Arrangement>> In the example shown in Figure 8, the first support pin 22a abuts the bottom surface of the non-coated area A2 of the substrate 9, while the second support pin 22b abuts the bottom surface of the coated area A1 of the substrate 9. Coated area A1 can also be considered the device area where the device is formed, so the first support pin 22a abuts the bottom surface of the non-device area of the substrate 9, while the second support pin 22b abuts the device area of the substrate 9. However, this is not necessarily the case.

Figure 12 shows a second example of the positional relationship between the substrate 9 and the first and second support pins 22a, 22b. In the example of Figure 12, all first support pins 22a abut against the lower surface of the peripheral area B1 of the substrate 9, while all second support pins 22b abut against the lower surface of the inner area B2 of the substrate 9. Conversely, all first support pins 22a avoid the lower surface of the inner area B2 of the substrate 9, rather than abut against it. Similarly, all second support pins 22b avoid the lower surface of the peripheral area B1 of the substrate 9, rather than abut against it.

As a result, the thick first support pins 22a are not located directly below the inner area B2 of the substrate 9. Therefore, even if the number, position, and shape of the coating areas A1 within the inner area B2 of the substrate 9 are changed, the coating areas A1 of the substrate 9 are supported only by the thin second support pins 22b. Consequently, the area of the substrate 9 where the coating film 90 is formed is supported only by the second support pins 22b. Consequently, even if the number, position, and shape of the coating areas A1 are changed, uneven drying of the coating film 90 can be suppressed.

<<Contact Area between 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 (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 in the peripheral area B1 supporting the substrate 9 may be larger than the second contact area.

This allows the frictional force between the first support pins 22a and the peripheral area B1 of the substrate 9 to be greater than the frictional force between the second support pins 22b and the substrate 9. Therefore, thicker first support pins 22a can reduce the amount of horizontal displacement of the substrate 9. On the other hand, a larger first contact area results in a greater amount of heat transferred between the first support pins 22a and the substrate 9. However, since these first support pins 22a support the peripheral area B1 of the substrate 9 (i.e., the non-coated area A2), they are less likely to cause temperature deviations in the coated area A1 of the substrate 9.

The second contact area between the second support pins 22b and the substrate 9 is smaller than the second contact area between the first support pins 22a and the substrate 9. This reduces the amount of heat transferred between the second support pins 22b and the substrate 9. Although the second support pins 22b support the coating area A1 of the substrate 9, the reduced amount of heat transferred between the second support pins 22b and the substrate 9 suppresses temperature variations in the coating area A1. Consequently, uneven drying of the coating film 90 is minimized.

<< Spacing Between Support Pins 22 >> Next, the spacing between the first support pins 22a and the spacing between the second support pins 22b will be described. Figure 13 shows a third example of the positional relationship between the substrate 9 and the first and second support pins 22a, 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 pins 22a are thicker than the second support pins 22b. Therefore, even if the spacing between the first support pins 22a is set wider than the spacing between the second support pins 22b, the substrate 9 can still be properly supported. Conversely, the spacing between the first support pins 22a can be set wider than the spacing between the second support pins 22b, as long as the substrate 9 can be properly supported while suppressing horizontal displacement of the substrate 9.

This reduces the number of first support pins 22a, thereby reducing the manufacturing cost of the pressure-reducing drying apparatus 1. Furthermore, the upper ends of the support pins 22 can wear out due to contact with the substrate 9. In other words, the support pins 22 are consumable and therefore require replacement. However, the fewer the number of support pins 22, the less time is required to replace the support pins 22.

<<Material of Support Pin 22>> The second support pin 22b can be formed, for example, from a porous resin. The term "porous resin" herein refers to a resin having a structure containing numerous fine pores. Such porous resins can be manufactured, for example, by foam molding, such as supercritical foaming. Polypropylene, for example, can be used as the resin. The average diameter of the fine pores formed within the resin can range from several nanometers to several tens of micrometers or less.

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

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

Furthermore, the entire second support pin 22b does not need to be made of a porous resin. For example, it is sufficient for at least the second contact portion 23b of the second support pin 22b to be made of a porous resin. For example, the second contact portion 23b can be made of a porous resin, while the second columnar portion 25b can be made of a non-porous resin. This can also reduce the amount of heat transferred between the second support pin 22b and the substrate 9. Of course, when the entire second support pin 22b is made of a porous resin, heat transfer can be further reduced.

The first support pin 22a can also be formed of a porous resin, similar to the second support pin 22b. This reduces the amount of heat transferred between the first support pin 22a and the substrate 9 through the contact area between the first support pin 22a and the peripheral area B1 of the substrate 9. Consequently, the deviation in the temperature distribution of the peripheral area B1 of the substrate 9 can be reduced. Furthermore, the temperature difference between the peripheral area B1 and the inner area B2 of the substrate 9 can be reduced, thereby reducing the transfer of heat between the peripheral area B1 and the inner area B2. Consequently, the increase in deviation in the temperature distribution at the end portion of the inner area B2 can be suppressed or avoided.

<3. Modifications> This disclosure is not limited to the single embodiment described above, and various modifications and improvements are possible without departing from the spirit of this disclosure.

In the embodiment described above, at least one of the two or more support pins 22 supporting the peripheral area B1 of the substrate 9 is sufficient as the first support pin 22a. In other words, some of the two or more support pins 22 supporting the peripheral area B1 of the substrate 9 may be the second support pins 22b. In short, the two or more support pins 22 supporting the peripheral area B1 of the substrate 9 may include both the first support pins 22a and the second support pins 22b. If one or more thick first support pins 22a support the peripheral area 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 area B1 are first support pins 22a.

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

Alternatively, the coating film 90 may be formed on the entire surface of the substrate 9 except for the peripheral area B1.

In the embodiment described above, the lifting portion 100 for lifting the support portion 20 may not be present. In this case, the plurality of support pins 22 may be fixed to a portion within the chamber 10 such as the upper surface of the bottom straightening plate 40 or to the chamber 10 such as the upper surface of the bottom plate 11.

In the embodiment described above, for example, chamber 10 has four exhaust ports 16a, 16b, 16c, and 16d, but this is not limiting. For example, chamber 10 may have any number of exhaust ports, from one to three, or even five or more. Furthermore, for example, separate valves Va, Vb, Vc, and Vd may not be present.

In the embodiment described above, the reduced pressure drying device 1 dries the coating film 90 on the substrate 9 by reducing pressure, but the present invention is not limited thereto. For example, the reduced pressure drying device 1 may also dry the coating film 90 on the substrate 9 by reducing pressure and applying heat.

In the embodiment described above, the sidewalls 12 of the chamber 10 are provided with a loading/unloading port 14 for the substrates 9, but the present invention is not limited thereto. For example, a structure may be employed in which the four sidewalls 12 and the top plate 13 of the chamber 10 form a single lid, and the lid can be separated from the bottom plate 11 and retracted upward. In this case, for example, the lid can be moved vertically by an opening/closing drive 16 or the like. Furthermore, the chamber 10 can be selectively configured to be in a state (a closed state) in which the lid contacts the bottom plate 11 via a sealing material such as an O-ring, thereby sealing the internal space 10s, and a state (an open state) in which the lid separates upward from the bottom plate 11, thereby opening the internal space 10s. Here, if the chamber 10 is in an open state, the substrate 9 can be loaded into and unloaded from 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 exhausting air from and supplying air to the inner space 10s, thereby reducing the pressure.

In the embodiment, for example, the supporting portion 20 may have various shapes. For example, the plurality of supporting plates 21 may also be a single integrated supporting plate 21.

In the embodiment, for example, the bottom straightening plate 40 and the side straightening plate 50 may be omitted.

In the embodiment described above, for example, various operations in the reduced pressure drying apparatus 1 may be started or ended in response to a user's operation on the input unit 804 or a signal input from an external device to the communication unit 806.

In the embodiment described above, for example, in the control unit 80, at least a portion of the functional structure implemented may include hardware such as dedicated electronic circuits.

Furthermore, it is of course possible to appropriately combine all or part of the embodiments and various modifications described above within a range that does not conflict.

1: Decompression drying device 9: Substrate 9op: Periphery (side) 10: Chamber 10s: Internal space 11: Bottom plate 11h, 40h: Through-holes 12: Side wall 13: Top plate 14: Load/unload port 15: Gate (gate valve) 16: Open/close actuator 16a, 16b, 16c, 16d: Exhaust port 16f: Air supply port 20: Support 21: Support plate 22: Support pin 22a: First support pin 22b: Second support pin 23a: First contact portion 23b: Second contact portion 25a: First columnar portion 25b: Second columnar portion 26a: First pedestal portion 26b: Second pedestal portion 27a: First external threaded portion 27b: Second external threaded portion 30: Exhaust section 31: Exhaust piping 31a, 31b, 31c, 31d: Individual piping 31e: Main piping 32: Vacuum pump 40: Bottom straightener 41: Diagonal line 50: Side straightener 60: Air supply section 61: Air supply piping 62: Air supply source 70: Pressure gauge 80: Control section 81: Open/Close control section 82: Lift 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: Drive 807m: Storage medium A1: Area (formed area, coated area) A2: Area (uncoated area) A3: Area (coated area) A4: Area (exposed area) B1: Peripheral area B2: Inner area B3: Boundary F1: First surface F2: Second surface Ga, Gb: Upward airflow H1: Lowering position H2: Ascending position S1-S4: Steps Va, Vb, Vc, Vd: Individual valves Ve: Main valve Vf: Air supply valve

Figure 1 is a diagram showing an example of a longitudinal cross-section of a reduced-pressure drying apparatus according to one embodiment. Figure 2 is a diagram showing an example of a transverse cross-section of a reduced-pressure drying apparatus according to one embodiment. Figure 3 is a diagram showing an example of a longitudinal cross-section of a reduced-pressure drying apparatus according to one embodiment. Figure 4 is a perspective view showing an example of a substrate. Figure 5 is a diagram showing an example of a longitudinal cross-section of a portion of a 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 a 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 functions that can be implemented in the control unit. Figure 11 is a flow chart illustrating an example of a reduced-pressure drying process according to one embodiment. Figure 12 is a diagram illustrating a second example of the relationship between the coating area of a substrate and the first and second support pins. Figure 13 is a diagram illustrating a third example of the relationship between the coating area of a substrate and the first and second support pins.

1: Pressure reduction drying device

9:Substrate

10: Chamber

10s: Interior space

11: Bottom plate

11h, 40h: Through hole

12: Side wall part

13: Top plate

14: Moving in and out

15: Gate section (gate valve)

16: Open and close the drive unit

20: Supporting part

21: Support plate

22: Support pin

22a: First support pin

22b: Second support pin

40: Bottom rectifier plate

50: Side rectifier

100: Lifting unit

100a: Main body

100b: Moving part

H1: descending position

H2: Ascending position

Claims (5)

A decompression drying device for drying a coating film formed on the upper surface of a substrate, the decompression drying device comprising: a chamber for accommodating the substrate; a plurality of support pins for supporting the substrate from below within the chamber; and an exhaust portion for exhausting gas within the chamber. The plurality of support pins include 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 a region of the substrate, which is located inward of the peripheral region and on which the coating film is formed, from below. The first support pins include first columnar portions of uniform width. The second support pin includes a second columnar portion of equal width. The difference between the width of the first columnar portion and the width of the second columnar portion is greater than 0.5 mm. The proportion of the second columnar portion in the vertical direction of the second support pin is the largest compared to the proportion of the remaining portion of the second support pin. The reduced-pressure drying device of claim 1, wherein: The inner region of the substrate is supported only by the second support pins. The reduced-pressure drying device according to claim 1, wherein: At least one of the first support pins supports an area of the inner region of the substrate other than the area where the coating film is formed. The reduced-pressure drying device of 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 reduced-pressure drying device according to claim 1, wherein: the second support pin is formed of a porous resin.