JP2002110535A - Wafer treatment device and method of drying wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer treatment device with which uneven drying of a wafer hardly occurs even when clean air is applied to the wafer at a high flow rate. SOLUTION: This wafer treatment device has a spin coater, an edge rinse unit and a drying acceleration unit. The spin coater coats a wafer W with a resist. The edge rinse unit performs other treatments on the wafer W coated with the resist. The drying acceleration unit is disposed between the spin coater and the edge rinse unit and accelerates drying of the wafer W by applying clean air to the wafer W coated with the resist from upward. This drying acceleration unit has a pad 26 generally surrounding the lower and side portions of the wafer W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing apparatus and a substrate drying method, and more particularly to a substrate processing apparatus provided with a drying acceleration processing section for applying clean air from above to a substrate coated with a coating liquid. The present invention relates to a substrate drying method including a step of applying clean air to a substrate.

[0002]

2. Description of the Related Art In a manufacturing process for performing various processes on a substrate, for example, a glass substrate for manufacturing a liquid crystal display, a substrate processing apparatus for performing a certain series of processes is used. Among these apparatuses, there is a substrate processing apparatus including a step of applying a coating liquid such as a resist coating liquid to a substrate.

For example, in a substrate processing apparatus for performing a photoresist coating process in a liquid crystal display manufacturing process, a photosensitive resin material of ultraviolet light is applied to a uniform thickness over the entire substrate surface. Specifically, a spin coating method that spreads the resist liquid dropped on the substrate by centrifugal force to rotate the substrate by centrifugal force to obtain a uniform thickness, and a roll coating method that transfers the resist liquid once attached to the groove on the roller surface to the substrate Is applied. Here, in order to obtain a uniform coating over a large area and an arbitrary thickness suitable for the subsequent etching conditions, etc., and also according to the characteristics of the coating method, a resist solution having an appropriate viscosity by controlling the amount of solvent is used. Selected.

[0004] Usually, the process proceeds to an exposure process after a photoresist coating process, but before this exposure process, a pre-bake (baking) process for evaporating a residual solvent is performed. Further, in some cases, an edge rinsing process for cleaning the vicinity of the end surface of the substrate may be performed from the viewpoint of preventing generation of particles and alignment at the time of exposure.

In a substrate processing apparatus including a series of photoresist coating steps as described above, the substrate is accommodated in a reduced pressure chamber immediately after the application of the resist, to promote the evaporation of the solvent and to dry the applied liquid to some extent. There is a vacuum drying device. The drying here suppresses the spread of the applied resist solution to the end face in the edge rinsing process.
However, when the substrate size is large, a large-sized decompression chamber is required, so that the decompression drying device becomes considerably expensive. In addition, when the pressure in the decompression chamber is reduced, it is inevitable that a certain amount of particles are entangled from the hermetically sealed portion, and the problem of self-electrostatic destruction of the charged substrate under reduced pressure is also significant.

[0006] For this reason, the applicant of the present application has proposed a substrate processing apparatus provided with a drying acceleration processing unit instead of a reduced-pressure drying apparatus, as disclosed in Japanese Patent Application Laid-Open No. 2000-012427. The drying promotion processing section included in the substrate processing apparatus promotes drying of the coating liquid by supplying clean air having a flow rate equal to or higher than a predetermined speed to the substrate.

[0007]

FIG. 1 of the above publication is disclosed.
In the substrate processing apparatus shown in FIG. 5, in order to prevent airflow (lateral wind) from the inside to the outside of the substrate from being generated at the periphery of the substrate, and to prevent drying unevenness (wind ripples) from occurring in the resist film to be dried, the substrate mounting table (substrate) The size of the support is considerably larger than the size of the substrate. Thereby, the side wind generated at the peripheral portion of the substrate is reduced, so that even when the substrate is exposed to the clean air at a relatively high speed in order to shorten the drying time, uneven drying is unlikely to occur.

However, there are cases where the substrate support cannot be made so large in size due to space constraints. Further, depending on the characteristics of the resist solution, the resist film may be dried in a state where unevenness is generated even if the generation of the cross wind in the peripheral portion of the substrate is small. In such a case, the flow rate of the clean air applied to the substrate cannot be increased, and the time required for drying increases.

An object of the present invention is to provide a substrate processing apparatus provided with a drying promotion processing section for promoting drying of a coating solution applied to a substrate in order to quickly transfer the substrate to processing in another processing section. An object of the present invention is to provide a substrate processing apparatus in which even when the substrate is applied to the substrate at a high flow rate, drying unevenness that occurs during substrate drying is small. Another object of the present invention is a substrate drying method for accelerating the drying of a coating liquid applied to a substrate in order to quickly transfer the substrate to processing in another processing unit. Another object of the present invention is to provide a method for drying a substrate, which causes less drying unevenness when the substrate is dried.

[0010]

According to a first aspect of the present invention, there is provided a substrate processing apparatus including a coating processing section, another processing section, and a drying promotion processing section. The application processing unit applies the application liquid to the substrate. The other processing unit performs another processing on the substrate on which the coating liquid has been applied. The drying promotion processing unit is disposed between the coating processing unit and another processing unit, and promotes drying of the substrate by applying clean air from above to the substrate coated with the coating liquid. The drying promotion processing section has a bat which substantially surrounds the lower side and the side of the substrate.

Here, in the drying promotion processing section, the substrate is dried by blasting the substrate with clean air from above, and the clean air flows from above the central portion of the substrate to below the substrate via the peripheral portion of the substrate. The bat is enclosed below and on the sides of the substrate so as not to go. Even if the flow rate of the clean air applied to the substrate is slightly increased, almost no crosswind from the inside to the outside is generated around the substrate, and the coating liquid on the substrate is dried during drying. Unevenness is suppressed. Further, since the flow rate of the clean air can be increased, the drying time is also shortened.

According to a second aspect of the present invention, there is provided a substrate processing apparatus.
Wherein the upper end of the side wall of the bat surrounding the side of the substrate is at a position higher than the upper surface of the substrate by 10 mm or more.

According to the test results by the inventor of the present application, the side wall of the bat surrounding the side of the substrate is 10 mm from the upper surface of the substrate.
It has been confirmed that the degree of occurrence of the crosswind is significantly reduced when the height is higher than the above. It is considered that this is because when the bat has a certain height of the side wall, the clean air stays in the bat and the cross wind around the substrate is less likely to be generated.

In view of this, the apparatus according to the present invention is configured such that the upper end of the side wall of the bat is located at a position higher than the upper surface of the substrate by 10 mm or more. In addition, the inventor of the present application has repeated the test, and according to the test results, the side wall of the bat which can suppress the cross wind most has the upper end located at a position about 40 mm higher than the upper surface of the substrate. Met.

A third aspect of the present invention is a substrate processing apparatus.
Or the apparatus according to 2, wherein the bottom surface of the bat is at a position higher than a position 50 mm below the upper surface of the substrate.
According to the test results by the inventor of the present application, when the bottom surface of the bat is far away from the substrate, particularly when the clean air starts to be applied to the substrate, the clean air flows from above the substrate central portion through the substrate peripheral portion to the substrate. The amount flowing downward has increased. Then, in order to suppress the drying unevenness due to the crosswind, it has been found that the bottom surface of the bat must be brought as close as possible to the substrate so that a state in which the clean air does not easily flow below the substrate must be created.

In view of this, in order to suppress the drying unevenness within an allowable level, the apparatus according to the present invention is configured such that the bottom surface of the bat is located at a position higher than the position 50 mm lower than the upper surface of the substrate.

If the required level of drying unevenness is so high that it is necessary to make the drying hardly occur, the distance between the top surface of the substrate and the bottom surface of the bat is reduced to 10 mm or less even if the structure is changed. It is desirable.

According to a fourth aspect of the present invention, there is provided a substrate processing apparatus.
4. The apparatus according to any one of items 1 to 3, wherein the bat surrounds the substrate while supporting the substrate. Here, since the bat also serves as the substrate support, the structure is simple and the cost is small.

According to a fifth aspect of the present invention, there is provided a substrate processing apparatus according to the first aspect.
4. The apparatus according to any one of items 1 to 3, wherein the drying promotion processing unit has a substrate support stand that supports the substrate, separately from the bat.

Here, since the substrate support is provided separately from the bat, it is easy to relatively move the bat and the substrate support. A substrate processing apparatus according to a sixth aspect is the apparatus according to the fifth aspect, further comprising a seal member. The seal member is arranged between the bat having an opening on the bottom surface and the substrate support. The substrate support is connected to a member that passes through the opening of the bat.

Here, an opening is provided in the bottom surface of the bat surrounding the substrate, the member is penetrated, and the member and the substrate support are connected. The member connected to the substrate support may be fixed to the substrate support or may be connected via a link mechanism or the like. With such a configuration, the relative movement between the bat and the substrate support can be achieved even when the substrate support is arranged in the bat so that the substrate can be easily supported.

Since the bat and the substrate support are separate members, a gap is formed between them. However, since a seal member is provided here, the gap between the bat and the substrate support is filled when necessary. Can be sealed. This suppresses the space below the substrate from communicating with the space outside the bat, and suppresses the flow of clean air from above the central portion of the substrate to below the substrate via the peripheral portion of the substrate.

According to a seventh aspect of the present invention, there is provided a substrate processing apparatus according to the fifth aspect.
Or the apparatus according to 6, wherein the drying promotion processing unit further includes a moving mechanism. The moving mechanism changes the relative height between the bat and the substrate support when the substrate is exposed to clean air from above.

The bat which surrounds the lower side and the side of the substrate is an important member for suppressing the generation of the cross wind around the substrate to prevent the drying unevenness. However, from the viewpoint of the drying time, the bat is a negative member for retaining the clean air. Work on.

Therefore, in the apparatus according to the present invention, a moving mechanism is provided to change the relative height position between the bat and the substrate support when the coating liquid is dried by clean air. That is, the relative height position between the bat and the substrate support is changed at the time of drying to change how the bat surrounds the substrate. For this reason, when the drying unevenness is likely to occur, the enclosure of the substrate can be strengthened, and when the risk of the occurrence of the drying unevenness is reduced, the enclosure of the substrate can be relaxed. This makes it possible to reduce drying time while suppressing drying unevenness.

In order to change the relative height position between the bat and the substrate support, the moving mechanism needs to move at least one of the bat and the substrate support up and down. In the case of a device in which it is difficult to move the base support, it is desirable to adopt a configuration in which the bat side is moved.

Also, if the flow of clean air impinging on the substrate changes suddenly, there is a high possibility that drying unevenness will occur.
It is desirable that the operation of the moving mechanism be gradually changed in accordance with the degree of drying.

[0028] The substrate processing apparatus according to claim 8 provides the substrate processing apparatus according to claim 7.
The side wall of the bat surrounding the side of the substrate is displaced from the side of the substrate by a change in the relative height position between the bat and the substrate support base by the moving mechanism.

Here, the relative height position between the bat and the substrate support is changed by the moving mechanism until the side wall of the bat surrounding the side of the substrate comes off the side of the substrate. In this way, the bat completely comes off the side of the substrate and the side of the substrate is opened, so that the amount and speed of the clean air flowing around the substrate can be increased. If this state is brought to the latter half of the drying promotion process in which the risk of occurrence of drying unevenness is extremely small, the drying time can be significantly reduced while suppressing drying unevenness.

According to a ninth aspect of the present invention, there is provided a substrate processing apparatus according to the seventh aspect.
Or the apparatus of claim 8, wherein the moving mechanism is configured to gradually move the substrate closer to an air supply that creates a flow of clean air.
Raise the substrate support.

Here, since the substrate support is gradually raised, the surrounding condition of the substrate by the bat is gradually loosened. That is, since the surroundings of the substrate are loosened as the drying proceeds, the unevenness of drying which is likely to occur in the early stage of drying is suppressed, and the flow of clean air is increased in the latter half of drying, so that the drying time is shortened.

In addition, as the substrate support rises, the substrate approaches the air supply source, so that the flow of clean air is further increased. This also contributes to shortening the drying time in the latter half of drying.

In the case where a structure for moving the substrate support, such as a printed board instead of a glass substrate, can be easily adopted, the configuration according to claim 9 can be easily adopted.

The air supply source in the present invention corresponds to a ceiling for generating a downflow of air in a clean room in which the apparatus is installed, and an air supply mechanism separately provided for promoting drying.

According to a tenth aspect of the present invention, there is provided the substrate processing apparatus according to any one of the seventh to ninth aspects, wherein the drying promotion processing section includes a substrate supporting section for supporting the substrate separately from the substrate supporting table. Have. Further, in this substrate processing apparatus, the support of the substrate by the substrate support and the support of the substrate by the substrate support are switched by the change in the relative height between the bat and the substrate support by the moving mechanism.

Here, since the substrate support is provided separately from the substrate support and the support of the substrate is switched during the drying, the uniformity of the drying of the coating solution on the substrate can be further improved. That is, if the substrate is supported at the same position for a long time, the thermal effect of the portion supporting the substrate affects the supported portion of the substrate, and the film pressure and the like near the supported portion may fluctuate. However, here, since the portion supporting the substrate changes during the drying, the uniformity of the drying of the coating liquid is improved.

It is to be noted that a plurality of substrate supports may be provided to switch the support of the substrate two or more times, or the substrate support may be configured to move so as to increase the number of times the substrate support is switched. It is.

An eleventh aspect of the present invention is the substrate processing apparatus according to any one of the first to tenth aspects, wherein the drying promotion processing section further includes an exhaust mechanism. The exhaust mechanism is
This is a mechanism for exhausting a lower space below the bat substrate. This exhaust mechanism increases the amount of exhaust according to the degree of drying of the substrate when the substrate is exposed to clean air from above.

The bat which surrounds the lower side and the side of the substrate is an important member for suppressing the generation of the cross wind around the substrate and preventing the drying unevenness. Work on.

Therefore, in the apparatus of the present invention, an exhaust mechanism is provided to exhaust the space below the bat located below the substrate. Specifically, when the coating liquid is being dried with clean air, the exhaust amount is increased in accordance with the degree of drying of the substrate. For this reason, the substrate (coating liquid)
When the drying progresses and drying unevenness hardly occurs,
The amount of exhaust increases, and a large amount of clean air flows from above the central portion of the substrate to below the substrate via the peripheral portion of the substrate. Thereby, the flow of the clean air around the substrate is increased, and the drying time is shortened. On the other hand, when the degree of drying is small, the amount of exhaust gas has not increased, so that drying proceeds gradually while suppressing drying unevenness.

At the beginning of drying, it is desirable that the exhaust mechanism does not exhaust at all. Claim 11
The operation of the exhaust mechanism described in (1) may be performed instead of the operation of the moving mechanism described in claim 7, or may be performed in addition to the operation of the moving mechanism described in claim 7.

A substrate processing apparatus according to a twelfth aspect is the apparatus according to any one of the first to eleventh aspects, wherein the drying promotion processing unit further includes an air supply mechanism for flowing clean air from above to the substrate. Have.

Here, since the drying promotion processing unit has its own air supply mechanism, the strength of the flow of the clean air is adjusted according to the type of the coating liquid, and the air volume is changed according to the degree of drying during drying. Can be easily done.

A thirteenth aspect of the present invention is the substrate processing apparatus according to the twelfth aspect, wherein the air supply mechanism has at least one of a higher temperature, a lower humidity, and a lower solvent concentration of the clean air.
One can do.

Here, when the temperature of the clean air is increased, the substrate can be dried in a shorter time. Further, even when the humidity of the clean air is reduced, the substrate can be dried in a shorter time.

Further, even when the concentration of the solvent in the clean air is reduced, the solvent content of the clean air is reduced, so that the substrate can be dried in a shorter time. The concentration of the solvent in the clean air may be reduced by lowering the solvent content of the clean air using a chemical adsorption filter or the like.

According to a fourteenth aspect of the present invention, there is provided a substrate drying method used in a drying process for drying a substrate after the application of a coating solution before another process, wherein the first step and the second step are performed. Have. In the first step, clean air is applied to the substrate. In the second step, the flow of the clean air around the substrate is gradually increased by gradually reducing the relative distance between the supply source of the clean air and the substrate, or by gradually increasing the air supply source that generates the flow of the clean air.

Here, the substrate is basically dried by the first step of blowing clean air to the substrate. In the second step, the flow of clean air around the substrate is gradually increased in order to reduce drying time of the substrate while suppressing drying unevenness. That is, when the drying is started, the flow of the clean air around the substrate is slow, but the second step is provided so that the flow of the clean air around the substrate becomes faster as the drying of the substrate proceeds. Therefore, in the present drying method, a slow flow of clean air hits the substrate in the initial stage of drying where drying unevenness is likely to occur. Will be hit.

As described above, according to the substrate drying method of the present invention, while suppressing drying unevenness which is likely to occur at the beginning of drying,
By gradually increasing the flow of clean air around the substrate,
Overall drying time is reduced.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment <Overall Configuration of Apparatus> FIG. 1 shows a substrate processing apparatus according to one embodiment (first embodiment) of the present invention. This substrate processing apparatus is an apparatus for resist coating that connects a plurality of processing units to a rectangular glass substrate (hereinafter, referred to as a substrate) to enable consistent processing. It can be connected to a device or the like.

This substrate processing apparatus is a single-wafer type apparatus, and includes a loading section 1, a spin coater section (coating processing section) 2, a drying acceleration processing section 3, an edge rinsing section 4, a placing section 5, and a baking section. 6. The substrate processing apparatus is disposed, for example, between a substrate cleaning apparatus 11 that is a pre-processing apparatus and an exposure machine 12 that is a post-processing apparatus.
Then, the substrate is carried into the carry-in section 1 by carrying means such as a conveyor, and is carried out from the baking section 6 to the exposure machine 12 by a carrying robot or the like. From the loading unit 1 to the placement unit 5, the substrates are transported by intermittent transfer sliders 7a to 7b which have a plurality of hands and sequentially transport the substrates to the adjacent processing unit.

The substrate processing apparatus is installed in a clean room 10 as shown in FIG. In the clean room 10, the HEPA filter (high efficiency pa)
The clean air flows into the room from the entire surface of the ceiling constituted by the rticulate air filter (10b), and the air flows out from the entire floor. That is, in the clean room 10, a one-way flow (downflow) occurs vertically. In the lower part of the clean room 10, a steel or stainless steel grating-like grating panel (floor panel) 10a that forms a free access space in the lower part is installed. The grating panel 10a is provided with a large number of suction ports. The air flow is generated by the blower 10c as shown in FIG.

<Structure of Drying Acceleration Processing Unit> Next, the structure of the drying acceleration processing unit 3 will be described. Drying promotion processing section 3
Is mainly composed of an air supply device 30 (see FIG. 3) for gently blowing clean air to the substrate W, a substrate support 21 on which the substrate W is mounted (see FIGS. 4 to 9), and a bat 26. ing.

(Air supply device) Air supply device 30
3 includes a HEPA filter 31, a blower (blower) 33, and a supply pipe (supply path) 32 connecting the HEPA filter 31 and the blower 33, as shown in FIG. The HEPA filter 31 has a particle collection rate of 99.97% or more for particles having a rated air volume of 0.3 μm and an initial pressure loss of generally 300P.
a is an air filter having the following performance. Although the HEPA filter 31 is used here, an ULPA filter may be used if necessary. The blower is a blower that supplies air to the HEPA filter 31 and may be installed in the clean room 10 or may be installed outside the clean room 10 because the HEPA filter 31 is arranged immediately above the substrate W. . When the blower 33 is installed in the clean room, the HEPA filter 10b in the clean room 10
The clean air that has passed through can be sent to the HEPA filter 31, and the installation of the HEPA filter 31 can be omitted. However, if particles may be generated by installing the blower 33 in the clean room 10, the blower 33 is
It is desirable to set it outside of zero. Also, blower 33
Is heated by a heater 34 disposed between the blower 33 and the supply pipe 32. That is, the air supply device 30 can increase the temperature of the clean air blown out from the HEPA filter 31 by operating the heater 34.

Further, the air supply device 30 blows air downward from the lower part of the HEPA filter 31 toward the substrate W as indicated by a dashed line arrow in FIG.
This air is clean air since it has passed through the HEPA filter 31. The flow velocity of the air near the surface of the substrate W is determined by the distance from the HEPA filter 31 to the substrate W and the output of the blower 33.

(Substrate Support) The substrate support 21 is shown in FIGS.
As shown in FIG. 8, it is a table for holding a rectangular substrate W in a horizontal state. As shown in FIG. 4, the substrate support 21 has a size substantially equal to the size of the substrate W (20 mm from the end surface of the substrate W).
The main body 21a has a rectangular body 21a whose end is somewhat smaller by about 25 mm or slightly smaller, and a plurality of substrate support pins 21b are provided on the upper surface of the main body 21a. Although the substrate W is a thin glass substrate of 500 to 1000 mm square, it is schematically shown in the drawings for easy understanding. That is, the drawing dimensions of the substrate W are different from the actual dimensions. Along with this, the drawing dimensions of the substrate support table 21 also
It is different from the actual size.

The substrate support 21 is fixed to the upper end of an elevating shaft 22 which is raised and lowered by an elevating device 23, and vertically moves by driving the elevating device 23.
The elevating shaft 22 is provided with an opening 26c of a bat 26 described later.
Penetrates. As the elevating device 23, for example, a device using an electric ball screw may be used.

(Bat) The bat 26 is mounted on the substrate support 21.
This is a thin plate structure that can enclose the lower side and the side of the substrate W held by the above, and is mainly composed of a bottom plate 26a and a side wall plate 26b as shown in FIG. Bottom plate 26
a is slightly larger than the substrate support 21 in plan view, and has an opening 26c at the center as shown in FIG. A seal member 29 such as an O-ring or a V-ring is mounted around the opening 26c of the bottom plate 26a. The seal member 29 is sandwiched between the main body 21a of the substrate support 21 and the bottom plate 26a when the butt 26 approaches the main body 21a of the substrate support 21. The side wall plate 26b extends vertically upward from the end of each side of the bottom plate 26a, and has a height (H1 +
H2).

The bat 26 moves vertically up and down by driving the lifting device 27. As the elevating device 27, for example, a device using an electric ball screw may be used. <Control and Operation of the Entire Apparatus> In this substrate processing apparatus, first, the substrate is carried from the loading section 1 to the spin coater section 2 by the intermittent transfer slider 7a, and a resist (coating liquid) is applied to the substrate. The spin coater unit 2 includes a resist supply system, a spin motor, a cup, and the like, and forms a uniform resist film on a horizontally mounted substrate by dropping the resist on the substrate and rotating the substrate. The substrate on which the resist film has been formed is carried to the drying promotion processing unit 3 and dried to a certain extent. The control and operation here will be described later. Thereafter, the substrate is moved to the edge rinsing section 4. In the edge rinse section 4,
In order to prevent the resist film on the end face of the substrate from being peeled off and generating dust, a process of removing the resist on the periphery of the substrate surface and the end face portion with a solvent is performed. The substrate that has been subjected to each of the processes related to the resist coating is transferred from the mounting unit 5 to the baking unit 6 by a robot (not shown). In the bake section 6, heat treatment is performed for the purpose of evaporating the residual solvent in the resist film on the substrate and enhancing the adhesion of the substrate. This bake section 6 has a plurality of heating sections and cooling sections,
The substrates are carried in and out of these in order. The substrate subjected to the heating and cooling processing is carried out to the exposure machine 12.

<Control / Operation of Drying Acceleration Processing Unit> Next, drying of a substrate in the drying acceleration processing unit 3 will be described.
Here, the substrate W (see FIG. 4) sent from the spin coater unit 2 by the slider 7a is first placed on the substrate support 21 as shown in FIG. At this time, the substrate support 21 is raised to a predetermined height by the lifting device 23.

When the substrate W rests on the substrate support 21 and the slider 7a comes off from above the substrate support 21, the butt 2
6 rises to the height position shown in FIG. Then, the HEP of the air supply device 30
Clean air is flowed downward from the A filter 31.

The height position of the substrate W in the initial stage of the drying shown in FIG. 6 is such that the distance from the upper surface of the substrate W to the upper end of the side wall plate 26b of the bat 26 is the dimension H1, and the height position of the bottom plate 26a of the bat 26 from the upper surface of the substrate W. The distance to the upper surface is a dimension H2. Here, the dimension H1 is 40 mm, and the dimension H2 is 10 mm. As these set dimensions, those in which the drying unevenness in the peripheral portion of the substrate W is minimized as a result of repeating the test are used. In addition, these dimensions in the initial stage of drying,
It has been confirmed that when the dimension H1 is 10 mm or more and the dimension H2 is 50 mm or less, drying unevenness in the peripheral portion of the substrate W is reduced.

As time elapses and the drying of the substrate W proceeds, the bat 26 is lowered stepwise (or steplessly). Thereby, the degree of surrounding the substrate W by the bat 26 is loosened. For example, at the stage shown in FIG. 7, the dimension H from the upper surface of the substrate W to the upper end of the side wall plate 26b of the bat 26 is set.
3 is 10 mm from the top surface of the substrate W to the bottom plate 2 of the bat 26.
The dimension H4 up to the upper surface of 6a is 40 mm. Before the state shown in FIG. 6 shifts to the state shown in FIG.
Steps may be provided.

At the final stage of drying, the upper surface of the substrate W may be higher than the upper end of the side wall plate 26b of the bat 26 as shown in FIG. 8, or the state shown in FIG. It may be the final stage.

When the drying of the substrate W is completed, the substrate support 21
Then, the substrate W is transferred to the slider 7c, and the substrate W is transferred to the edge rinse section 4 by the slider 7c. <Features of Apparatus> (1) In the drying promotion processing unit 3 of the present apparatus, clean air is blown downward from the air supply apparatus 30 toward the substrate W. The flow of the clean air is rectified by passing through the HEPA filter 31. Since such rectified clean air hits the substrate W, the substrate W
The resist on the surface is dried while its surface shape is leveled. Since the solvent gas of the evaporated resist near the surface of the substrate W is swept away by the clean air, the drying of the substrate W is promoted.

Further, since the clean air is blown to the substrate W, there is no fear that particles and the like adhere to the substrate W. (2) In the drying promotion processing section 3 of the present apparatus, the flow of the clean air to the substrate W is generated by the air supply device 30. Although it is possible to dry the substrate W using the downflow in the clean room 10 as it is, an air supply device 30 is separately provided here to dry the substrate W in a shorter time.

The heater 3 is provided in the air supply device 30.
4, the temperature of the cleaning air supplied to the substrate W in the spin coater 2 can be increased in accordance with the type of resist applied to the substrate W. Thereby, it is possible to further promote the drying of the substrate W in the drying promotion processing unit 3.

(3) In the drying promotion processing section 3 of the present apparatus, the drying of the substrate W is promoted by irradiating the substrate W with clean air from above, and the clean air passes from above the central portion of the substrate W to the peripheral portion. In order not to flow below the substrate W, the lower side and the side of the substrate W are surrounded by the bat 26.
Thus, even if the flow rate of the clean air applied to the substrate W is slightly increased, a crosswind from the inside to the outside is hardly generated in the peripheral portion of the substrate W, and the cross-section on the substrate W during drying is slightly increased. Drying unevenness of the resist film is suppressed. Also, since the flow rate of clean air can be increased,
The drying time is also shorter.

If, in an apparatus without the bat 26, clean air with a high flow velocity is applied to the substrate W,
As shown in FIG. 10, drying unevenness (wind ripple UE) occurs on the substrate W. As shown in FIG. 10A, when air flows from above onto the substrate W placed on the substrate support 321, a weak turbulent flow F1 occurs in the center of the substrate W, but the peripheral portion of the substrate W , An airflow F2 from the inside to the outside of the substrate W is generated. This air flow F2 is shown in FIG.
As shown in the enlarged plan view of (b), the flow tends to flow in almost one direction along the surface of the substrate, and a so-called wind ripple UE is formed on the dried resist film along the flow direction of the gas flow F2. There is a possibility that it will be possible (see FIG. 10C).

On the other hand, in the drying promotion processing section 3 of the present apparatus, the substrate W is surrounded by the bat 26 at least in the initial stage of the drying, and therefore, as shown in FIG. The airflow (crosswind) from outside to the outside is suppressed, and the wind ripple UE hardly occurs.

(4) According to the test results by the inventor of the present invention, when the side wall plate 26b of the bat 26 surrounding the side of the substrate W is higher than the upper surface of the substrate W by 10 mm or more, the degree of occurrence of the side wind is significantly reduced. Has been confirmed to be.

In view of this, the drying promotion processing section 3 of the present apparatus is configured such that the upper end of the side wall plate 26b of the bat 26 is at a position higher than the upper surface of the substrate W by 10 mm or more.
Specifically, according to the results obtained from the repetition of the test, the bat 26 having the dimension that can minimize the
(The upper end of the side wall plate 26b is about 40 mm higher than the upper surface of the substrate W.
That are at a higher position).

According to the test results by the inventor of the present invention, in order to suppress drying unevenness (wind ripples) due to cross wind, the bottom plate 26a of the bat 26 is brought as close to the substrate W as possible.
It has been found that it is necessary to create a state in which clean air does not easily flow below the substrate W.

In view of this, in the drying promotion processing unit 3 of the present apparatus, the bat 2
6, so that the bottom plate 26a is positioned higher than a position 50 mm below the upper surface of the substrate W. Specifically, a bat 26 (the bottom plate 26a is close to the upper surface of the substrate W up to about 10 mm) having almost no drying unevenness is employed.

(5) In the drying promotion processing section 3 of the present apparatus, a seal member 29 such as an O-ring is mounted around the opening 26c of the bottom plate 26a of the bat 26. As shown in FIG. 6, this seal member 29
Rises, and when the bat 26 approaches the main body 21a of the substrate support 21, the butt 26 is sandwiched between the main body 21a of the substrate support 21 and the bottom plate 26a to seal between the two 21a, 26a.

For this reason, even when the opening 26c through which the elevating shaft 22 for vertically moving the substrate support 21 is passed is opened in the bottom plate 26a, the periphery of the substrate W in the initial stage of drying shown in FIG. The space is completely closed downward. Therefore, the phenomenon that the clean air flows below the substrate W via the peripheral portion of the substrate W at the initial stage of the drying of the substrate W is almost completely suppressed, and the occurrence of drying unevenness is further reduced. Such sealing is particularly effective when a sensitive chemical such as a color resist is used.

(6) The bat 26 surrounding the lower side and the side of the substrate W is an important component that suppresses the generation of the cross wind around the substrate W and prevents uneven drying. From the viewpoint of the drying time, In this case, the clean air stays in the bat 26, so that it acts negatively.

In order to reduce such a problem,
In the drying promotion processing section 3 of the present apparatus, an elevating device 27 for moving the bat 26 up and down is provided, and the bat 26 is controlled to gradually descend during drying. Thereby, when drying unevenness is likely to occur as in the early stage of drying, the surrounding condition of the substrate W by the bat 26 is strengthened, and in the latter half of drying when the risk of occurrence of drying unevenness is reduced, the surrounding condition of the substrate W is relaxed. Therefore, in the early stage of drying,
The occurrence of drying unevenness is suppressed, and in the latter stage of drying, the enclosure is loosened and the flow of clean air around the substrate W is increased, thereby shortening the drying time.

Here, in order to change the relative height position between the bat 26 and the substrate support 21, the bat 26 is moved during the drying of the substrate. This is better than moving the base support 21 supporting the large and thin glass substrate W.
This is because it is easier to move the bat 26.

(7) As shown in FIG. 8, if the side wall plate 26b of the bat 26 is separated from the side of the substrate W in the final stage of drying, the side of the substrate W is opened. The amount and speed of the clean air flowing around the substrate W is further increased, and the drying time is greatly reduced.

[Second Embodiment] The air supply device 30 of the first embodiment may have an air volume adjusting function and a humidity adjusting function.

When the air supply device 30 is provided with an air volume adjusting function for adjusting the amount of cleaning air supplied to the substrate W, the amount of air supplied to the substrate W in the spin coater 2 depends on the type of resist applied to the substrate W. It can be adjusted, and the dried state of the substrate W can be optimized. Specifically, in addition to adjusting the output of the blower 33, a damper is provided in the supply pipe 32, and the HEPA filter 3
There is a method of adjusting the distance from 1 to the substrate W.

When the air supply device 30 is provided with a humidity adjustment function for adjusting the humidity of the cleaning air supplied to the substrate W, the air is supplied to the substrate W according to the type of resist applied to the substrate W in the spin coater 2. The humidity of the cleaning air can be adjusted, and the dry state of the substrate W can be optimized. Specifically, there is a method of providing a dehumidifying device on the suction side or the blowing side of the blower 33.

[Third Embodiment] The air supply device 30 of the first embodiment may be equipped with a chemical adsorption filter. In this case, since the content of the solvent contained in the cleaning air impinging on the substrate W decreases, the drying can be performed in the drying promotion processing unit 3 in a shorter time.

[Fourth Embodiment] In this embodiment, an air supply device 40 shown in FIG. 11 is used in place of the air supply device 30 of the first embodiment.

The air supply device 40 shown in FIG.
It comprises a PA filter 41 and a blower 42. The HEPA filter 41 is arranged above the substrate W placed on the substrate support 21, and the blower 42
It is arranged above the EPA filter 41. The HEPA filter 41 is an air filter similar to the HEPA filter 31, and the blower 42 is a blower similar to the blower 33. The air supply device 40 blows air downward from the lower part of the HEPA filter 41 toward the substrate W, as indicated by a dashed line arrow in FIG. This air is clean air that is the clean air that has flowed down from the HEPA filter 10b of the clean room 10 by the operation of the blower 42 and has further passed through the HEPA filter 41.

Here, in addition to the HEPA filter 41, a blower 42 is also disposed above the substrate W, and the HEPA above the substrate W in the clean room 10.
Clean air that has just left the filter 10b is HEPA
It can be blown out to the substrate W via the filter 41.

[Fifth Embodiment] In the first embodiment, the bat 26 can be moved up and down by the lifting device 27. However, as shown in FIGS. 12 to 15, the bat 26 can be fixed. It is.

<Control / Operation of Drying Acceleration Processing Unit> In the apparatus of the present embodiment, the substrate W (see FIG. 12) sent from the spin coater unit 2 by the slider 7a first receives the substrate support as shown in FIG. It is placed on the table 21. At this time, the substrate support 21 is raised to a predetermined height by the lifting device 23.

When the substrate W is transferred onto the substrate support 21, the slider 7 a comes off from above the substrate support 21, and the substrate support 21 descends to the position shown in FIG. From which clean air begins to flow downward.

The height position of the substrate W in the initial stage of the drying shown in FIG. 14 is such that the distance from the upper surface of the substrate W to the upper end of the side wall plate 26b of the bat 26 is the dimension H1, and the height position of the bottom plate 26a of the bat 26 from the upper surface of the substrate W. The distance to the upper surface is a dimension H2. Each of the dimensions H1 and H2 is 4 as in the first embodiment.
0 mm and the dimension H2 is 10 mm.

As time elapses and drying of the substrate W proceeds, the substrate support 21 is raised stepwise (or steplessly). Thereby, the degree of surrounding the substrate W by the bat 26 is loosened. For example, in the final stage shown in FIG. 15, the upper surface of the substrate W is higher than the upper end of the side wall plate 26b of the bat 26.

<Features of Apparatus> Here, the substrate support 21
Gradually rises, so that the surrounding condition of the substrate by the bat 26 gradually loosens. That is, as the drying of the substrate W progresses, the surrounding condition of the substrate W is loosened, so that drying unevenness that is likely to occur in the early stage of drying is suppressed, and the flow of clean air is increased in the latter half of drying, so that the drying time is shortened.

Further, as the substrate support 21 rises, the substrate W approaches the HEPA filter 31 of the air supply device 30, so that the flow of the clean air further increases. This also contributes to shortening the drying time in the latter half of drying.

The configuration of the present embodiment (the substrate support 21
Is a configuration that is particularly easy to adopt when it is easy to adopt a structure for moving the substrate support 21 such as a printed board instead of a glass substrate.

[Sixth Embodiment] In the first embodiment, the bat 26 is lowered during drying, and in the fifth embodiment, the substrate support table 21 is raised during drying, thereby loosening the surrounding state of the substrate W by the bat 26. , The substrate W as the drying proceeds
The flow of the clean air around the bat 26 is gradually increased, but the same effect can be obtained by controlling the exhaust of the lower space of the bat 26 instead.

<Structure of Drying Acceleration Processing Unit> The apparatus of this embodiment is provided with an exhaust mechanism 50 for exhausting air from the space below the bat 26 as shown in FIG. Exhaust mechanism 50
Has an exhaust pipe 51, an exhaust bellows 52, an automatic control damper 53, and an exhaust fan (not shown).

The exhaust pipe 51 is connected to an exhaust fan. One end of an exhaust bellows 52 is connected to an end of the exhaust pipe 51. The bellows 52 for exhausting the bat 26
Are connected to a plurality of holes provided in the bottom plate 26a. The exhaust pipe 51 is provided with the bellows 5 for exhaust.
Automatically controlled damper 5 arranged between 2 and the exhaust fan
3 built-in. The opening degree of the automatic control damper 53 is adjusted by a control unit (not shown), and the displacement from the lower space of the bat 26 can be gradually increased from zero.

<Control / Operation of Drying Acceleration Processing Unit> In the apparatus of the present embodiment, the exhaust of the lower space of the bat 26 is controlled without relative movement between the substrate support 21 and the bat 26 during substrate drying. As a result, the flow of clean air around the substrate W is gradually increased. Specifically, FIG.
Alternatively, the exhaust gas is controlled so as to have an exhaust curve shown in FIG.

At the time of carrying in the substrate until time t1, and at time t1
During the initial drying from time t2 to time t2, the displacement is 0
And At this time, as shown in FIG. 16, the automatic control damper 53 is in the fully closed state. Therefore, at the time of initial drying, as shown in FIG. 16, the clean air flowing downward from the HEPA filter 31 hardly flows below the substrate W, and becomes a vortex-like weak turbulent flow on the substrate W.

From time t2 to time t3, the opening degree of the automatic control damper 53 is increased, and the exhaust amount is gradually increased. Accordingly, the flow of the clean air around the substrate W also gradually increases, and a portion of the clean air from the HEPA filter 31 passes through between the side wall plate 26b of the bat 26 and the end surface of the substrate W, and Exhaust pipe 5 from lower space
It will flow to 1.

Then, near time t3, as shown in FIG. 17, the opening of the automatic control damper 53 is almost fully opened, and the flow of clean air around the substrate W is considerably increased.

After the time t3, the drying promotion process is completed, and the displacement is returned to zero. <Characteristics of Apparatus> In the drying promotion processing unit of the present apparatus, as shown in FIG. 18, when the substrate W is dried with clean air, the exhaust amount is increased in accordance with the degree of drying of the substrate W. That is, when the drying of the substrate W progresses to a stage where the drying unevenness hardly occurs, the exhaust amount is increased and the substrate W
The flow of the clean air around is strengthened to shorten the drying time. On the other hand, when the degree of drying is small, the exhaust amount is set to 0 to suppress drying unevenness.

[Seventh Embodiment] In the sixth embodiment,
Although the bat 26 and the substrate support 21 are moved relative to each other during drying, the exhaust of the lower space of the bat 26 is controlled, but both may be combined.

For example, as shown in FIG. 19, during the initial drying from time t1 to time t2, the exhaust amount is set to 0, and the substrate support table 21 is positioned at the lower part in the bat 26, and From the time t2 to the time t3, the substrate support 21 is
It is conceivable to move relatively from the middle part to the top.

[Eighth Embodiment] In each of the above embodiments, a rectangular substrate support 21 and a bat 26 in plan view are assumed for a rectangular substrate W, but as shown in FIG.
For the square substrate W, a circular substrate support table 121 and a butt 126 may be employed.

Note that the number of support pins 121b of the substrate support table 121 in FIG. 20 is smaller than the actual number in order to make the drawing easier to see. Ninth Embodiment In the first embodiment, the support pins 21
Although the substrate supporting table 21 of the type in which the substrate W is placed on the substrate b is employed, a substrate supporting table provided with a vacuum suction mechanism may be employed. In this case, it is easier to set the distance between the upper surface of the substrate W and the bottom plate of the bat in the initial stage of drying as compared to the case of the substrate support having the support pins.

[Tenth Embodiment] In the first embodiment, the bat 26 is provided separately from the substrate support 21, but the bat may be formed by using the substrate support.

In the apparatus shown in FIG.
The side wall plate 226b extends upward from outside the portion where the substrate W is placed. Thus, a bat 226 in which the substrate support 221 is the bottom surface and the side wall plate 226b is the side surface can be configured. In this case, the substrate support 221
Since the bat 226 and the bat 226 are integrated, they cannot be moved relative to each other, but the configuration is extremely simple and the cost can be kept low.

[Eleventh Embodiment] In the first embodiment, the units are arranged in the order of the spin coater unit 2, the drying promotion processing unit 3, and the edge rinsing unit 4, and the processing for the substrate is performed in this order. Alternatively, the units may be arranged in the order of the spin coater 2, the edge rinsing unit 4, and the drying promotion processing unit 3, and the substrate processing may be performed in this order.

[Twelfth Embodiment] In the first embodiment, as shown in FIG. 6 and the like, the substrate W is always supported by the substrate support 21 during the drying of the substrate.
As shown in FIG. 3, a bat-side substrate support pin 28 may be provided inside the bat 26 so that the substrate support by the substrate support 21 and the substrate support by the bat-side substrate support pin 28 are switched during drying. it can. In this case, the uniformity of the resist film on the substrate can be kept better.

Here, the bottom plate 26a of the bat 26
A plurality of butt-side substrate support pins 28 are fixed. The butt-side substrate support pins 28 are positioned in a plane around the substrate support 21 and can support the substrate W within the bat 26.

At the beginning of the drying process, the substrate support 21 is stopped at a position above the upper end of the butt-side substrate support pins 28, and the substrate W is
(See FIG. 22). Then, when approximately half of the drying processing time has elapsed, FIG.
As shown in (2), the substrate support 21 is further lowered to stop the substrate support 21 at a position below the upper end of the butt-side substrate support pin 28. Then, the substrate W is supported by the butt-side substrate support pins 28 instead of the substrate support table 21.

As described above, during the drying processing time, the substrate W
By changing the position where the substrate W is supported by changing the position, the uniformity of the resist film formed on the substrate W can be maintained more favorably. In other words, if the substrate W is supported at the same position for a long time, the thermal effect of the members (pins and the like) supporting the substrate W affects the supported portion of the substrate W, and the film pressure near the supported portion is increased. May fluctuate,
By changing the substrate W, the occurrence of a trace called a pin trace due to a change in the film pressure is suppressed.

Although FIGS. 22 and 23 show an example in which the substrate W is changed only once during the drying processing time, a plurality of sets of the bat side substrate support pins 28 are provided.
It is also possible to adopt a configuration that enables ascending and descending for each pair. If the substrate W is first supported by the first set and then the substrate W is supported by the second set, the substrate W can be changed more than once,
Occurrence of membrane pressure fluctuation is more reliably suppressed.

[0116]

According to the present invention, in the drying acceleration processing section,
Since the bat surrounds the lower side and the side of the substrate to which the clean air is applied from above, even if the flow rate of the clean air applied to the substrate is slightly increased, the cross wind from the inside to the outside hardly occurs around the substrate, Drying unevenness of the coating liquid on the substrate during drying is suppressed.

The present invention is not limited to a substrate processing apparatus / substrate drying method for a glass substrate for a liquid crystal display device, and a substrate processing apparatus / substrate drying method for each target substrate such as a semiconductor wafer and a PDP glass substrate. Can also be applied.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a substrate processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a clean room.

FIG. 3 is a schematic diagram of an air supply device of a drying acceleration processing unit.

FIG. 4 is a schematic view of the periphery of a substrate support and a bat in a drying promotion processing unit.

FIG. 5 is an operation diagram of the drying promotion processing unit when the substrate is dried.

FIG. 6 is an operation diagram of the drying promotion processing unit when the substrate is dried.

FIG. 7 is an operation diagram of the drying promotion processing unit when the substrate is dried.

FIG. 8 is an operation diagram of the drying promotion processing unit when the substrate is dried.

FIG. 9 is an operation diagram of the drying promotion processing unit when the substrate is dried.

FIG. 10 is a diagram illustrating a state of substrate drying when there is no bat.

FIG. 11 is a schematic diagram of an air supply device according to a fourth embodiment.

FIG. 12 is an operation diagram of a drying promotion processing unit according to a fifth embodiment when a substrate is dried.

FIG. 13 is an operation diagram of the drying promotion processing unit according to the fifth embodiment when the substrate is dried.

FIG. 14 is an operation diagram of the drying promotion processing unit according to the fifth embodiment when the substrate is dried.

FIG. 15 is an operation diagram of the drying promotion processing unit according to the fifth embodiment when the substrate is dried.

FIG. 16 is a schematic diagram of a drying processing accelerating unit according to a sixth embodiment.

FIG. 17 is an operation diagram of the drying promotion processing unit according to the sixth embodiment when the substrate is dried.

FIG. 18 is a diagram illustrating an exhaust curve when a substrate is dried by a drying promotion processing unit according to a sixth embodiment.

FIG. 19 is a diagram illustrating an exhaust curve and a relative position between a substrate support and a bat when a substrate is dried in a drying promotion processing unit according to a seventh embodiment.

FIG. 20 is a schematic view of a drying promotion processing unit according to an eighth embodiment.

FIG. 21 is a schematic diagram of a drying promotion processing unit according to a tenth embodiment.

FIG. 22 is an operational diagram of the drying promotion processing unit according to the twelfth embodiment when drying a substrate.

FIG. 23 is an operational diagram of the drying promotion processing unit according to the twelfth embodiment when drying a substrate.

[Explanation of symbols]

 Reference Signs List 2 spin coater section (coating processing section) 3 drying promotion processing section 4 edge rinse section (other processing section) 6 bake section 21 substrate support 23 elevating device (moving mechanism) 26 bat 26a bottom plate (bottom surface) 26b side wall plate (side wall) 26c opening 27 elevating device (moving mechanism) 28 butt-side substrate supporting pin (substrate supporting portion) 29 sealing member 30 air supply device (air supply mechanism) 50 exhaust mechanism W substrate

Claims (14)

[Claims] A coating unit configured to apply a coating liquid to the substrate; another processing unit configured to perform another processing on the substrate coated with the coating liquid; A bat that is disposed at a side of the substrate and substantially surrounds a lower side and a side of the substrate, and a drying promotion processing unit that irradiates the substrate coated with the coating liquid with clean air from above. 2. The substrate processing apparatus according to claim 1, wherein a side wall of the bat surrounding a side of the substrate has a top end located at least 10 mm higher than an upper surface of the substrate. 3. A bottom surface of the bat is 50 degrees from an upper surface of the substrate.
3. The substrate processing apparatus according to claim 1, wherein the substrate processing apparatus is located at a position higher than a position lowered by mm. 4. 4. The substrate processing apparatus according to claim 1, wherein the bat surrounds the substrate while supporting the substrate. 5. The drying promotion processing section has a substrate support stand for supporting a substrate, separately from the bat.
4. The substrate processing apparatus according to any one of items 1 to 3. 6. A bottom surface of the bat is provided with an opening, the substrate support is connected to a member penetrating the opening, and a seal disposed between the bat and the substrate support. The substrate processing apparatus according to claim 5, further comprising a member. 7. The drying promotion processing unit further includes a moving mechanism for changing a relative height position between the bat and the substrate support when the substrate is exposed to clean air from above. The substrate processing apparatus according to claim 5, wherein the substrate processing apparatus is preferably changed gradually in accordance with a drying condition. 8. A side wall of the bat surrounding a side of the substrate is displaced from a side of the substrate by a change in a relative height position between the bat and the substrate support base by the moving mechanism. A substrate processing apparatus according to claim 1. 9. The substrate processing apparatus according to claim 7, wherein the moving mechanism raises the substrate support so that the substrate gradually approaches an air supply source that generates the flow of the clean air. 10. The drying promotion processing section has a substrate supporting section for supporting a substrate separately from the substrate supporting table, and a relative height position between the bat and the substrate supporting table by the moving mechanism. The substrate processing apparatus according to any one of claims 7 to 9, wherein the change in the state switches between support of the substrate by the substrate support and support of the substrate by the substrate support. 11. The drying promotion processing unit further includes an exhaust mechanism for exhausting a lower space below the substrate of the bat, and the exhaust mechanism applies clean air to the substrate from above. The substrate processing apparatus according to any one of claims 1 to 10, wherein the amount of exhaust is increased in accordance with the degree of drying of the substrate during the operation. 12. The substrate processing apparatus according to claim 1, wherein the drying promotion processing unit further includes an air supply mechanism for flowing the clean air from above to the substrate. 13. The substrate processing apparatus according to claim 12, wherein said air supply mechanism can perform at least one of a higher temperature, a lower humidity, and a lower solvent concentration of said clean air. 14. A substrate drying method used in a drying process for drying a substrate after a coating process of a coating solution before another process, wherein a first step of applying clean air to the substrate; A second step of gradually reducing the relative distance between the supply source and the substrate or gradually increasing the air supply source for producing the flow of the clean air to gradually increase the flow of the clean air around the substrate. Method.