JP2003257925A - Spinning treatment apparatus and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinning treatment apparatus which can prevent the leak of an atmosphere in a treatment vessel to an external side and the entry of external air when a semiconductor wafer is carried into the treatment vessel or carried out to the external side. <P>SOLUTION: The spinning treatment apparatus comprises a treatment vessel 1 provided with a semiconductor wafer entrance 34 which is opened and closed by a shutter 35, a cup body 2 provided in the treatment vessel, a rotating table 16 which is driven to rotate while it is provided in the cup body and holding semiconductor wafers, a fan filter unit 32 for guiding clean air into the treatment vessel provided at the upper part of the treatment vessel, an exhaust pump 6 to exhaust the clean air supplied to the treatment vessel from the fan filter unit, and a path 26 for controlling the amount of the clean air supplied to the treatment vessel and the amount of the clean air exhausted from the cup body to keep pressure in the treatment vessel to almost the atmospheric pressure when the semiconductor wafers are carried in and out to and from the treatment vessel by opening the entrance 34. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin processing apparatus and a spin processing method for performing processing with a processing liquid while rotating a substrate and processing for removing the processing liquid from the substrate and drying it.

[0002]

2. Description of the Related Art When manufacturing a semiconductor device or a liquid crystal display device, there is a lithographic process for forming a circuit pattern on a substrate such as a semiconductor wafer or a glass substrate. In this lithographic process, as is well known, a resist is applied to the above substrate, light is irradiated through a mask on which a circuit pattern is formed, and then a portion of the resist which is not irradiated (or light is irradiated). The circuit pattern is formed on the substrate by repeating a series of steps such as removing the removed portion) and etching the removed portion a plurality of times.

In the above series of steps, if the substrate is contaminated, the circuit pattern cannot be precisely formed, which causes defective products. Therefore, when the circuit pattern is formed in each step, the substrate is cleaned so that fine particles such as resist and dust do not remain.

A spin processing apparatus is known as an apparatus for cleaning the substrate. This spin processing apparatus has a processing tank, and a cup body is provided in this processing tank.
A rotary table is provided in the cup body, and the substrate is detachably held on the rotary table.

When the substrate is held on the turntable and the treatment liquid is supplied to the substrate while the turntable is rotated, the turntable is rotated at a higher speed than the treatment with the treatment liquid. The substrate is dried.

ULPA and HEPA are provided above the processing tank.
A fan / filter unit such as is provided to supply clean air into the processing tank when processing a substrate. A discharge pipe is connected to the bottom of the cup body. An exhaust pump is connected to this discharge pipe. As a result, the clean air supplied from the fan / filter unit into the processing tank passes through the cup body and is discharged from the discharge pipe.

As described above, when the substrate is processed, clean air is supplied from the fan / filter unit into the processing tank, passes through the cup body, and is discharged, so that mist generated when the substrate is dried is generated in the cup body. And prevents floating in the treatment tank. This prevents mist from adhering to the substrate during the drying process and causing contamination.

A loading / unloading port for loading / unloading the substrate is provided on one side of the processing bath, and the loading / unloading port can be opened and closed by a shutter. When supplying an unprocessed substrate to the rotary table or taking out a dried substrate from the rotary table, the loading / unloading port is opened and the substrate is loaded / unloaded by a robot or the like.

[0009]

The pressure in the processing tank may be set to, for example, a negative pressure in order to prevent the mist generated during the drying process from floating in the processing tank. That is, by setting the amount of clean air supplied from the fan / filter unit into the processing tank to be slightly smaller than the amount of exhaust air discharged from the exhaust pipe, the mist in the processing tank can be efficiently discharged. I have to.

In such a state, if the loading / unloading port is opened for loading / unloading the substrate, the outside air will flow into the negative pressure processing tank. Even if the processing tank is installed in the clean room, the gas in the clean room contains particles, so that the substrate may be contaminated by the particles flowing into the processing tank.

In order to prevent outside air from flowing into the processing tank, it may be considered to maintain the pressure in the processing tank at a positive pressure. In that case, if the loading / unloading port is opened to load / unload the substrate, the gas in the processing tank will flow out. The gas in the processing tank contains a mist-like processing liquid. A harmful chemical solution may be used as the processing solution. Therefore, if the gas containing the mist-like treatment liquid flows out of the treatment tank, the working environment of the clean room may be deteriorated, which is not preferable.

According to the present invention, when a substrate is put into or taken out of a processing bath, the atmosphere in the processing bath is prevented from flowing out and the outside air is prevented from flowing into the processing bath. It is to provide a processing method.

[0013]

According to a first aspect of the present invention, in a spin processing apparatus for performing processing with a processing liquid and processing for removing the processing liquid while rotating the substrate, a loading / unloading port of the substrate opened / closed by a shutter. , A cup body provided in the treatment bath, a rotary table provided in the cup body for holding and rotating the substrate, and a treatment table provided above the treatment bath. A fan / filter unit for introducing clean air into the tank, a discharging means for discharging the clean air supplied from the fan / filter unit into the processing tank through the cup body, and the substrate with the inlet / outlet opening opened. And the cup body so that the pressure in the processing tank becomes almost atmospheric pressure when the water is taken in and out of the processing tank. It has and a flow rate adjusting means for controlling the flow rate of the clean air discharged in a spin processing apparatus according to claim.

According to a second aspect of the present invention, the cup body has a lower cup and an upper cup that is vertically movable with respect to the lower cup, and the flow rate adjusting means is provided in the processing tank. 2. The spin process according to claim 1, wherein the flow path is formed by the inner peripheral surface of the upper cup and the outer peripheral surface of the rotary table when the upper cup is lowered when the substrate is taken in and out. On the device.

According to a third aspect of the present invention, the cup body has a lower cup and an upper cup that is vertically movable with respect to the lower cup, and the flow rate adjusting means includes the lower cup and the upper cup. The upper cup has a first through hole and a second through hole respectively formed therein, and these first and second through holes are in a non-opposing state when the upper cup rises and face each other when the upper cup descends. The spin processing apparatus according to claim 1, wherein:

According to a fourth aspect of the invention, the flow rate adjusting means is
The control device for controlling the amount of clean air supplied into the processing tank by the fan / filter unit and the amount of air discharged from the inside of the cup by the discharge means. Item 2. The spin processing apparatus according to item 2.

According to a fifth aspect of the present invention, a spin treatment is performed in which a treatment liquid is treated and a treatment liquid is removed while the substrate is rotated in a treatment tank having an opening / closing port opened and closed by a shutter on one side. In the method, there is provided a spin processing method, wherein when the substrate is loaded into or unloaded from the processing bath by opening the loading / unloading port, the pressure in the processing bath is set to about atmospheric pressure.

According to the present invention, the loading / unloading port of the processing bath is opened, and when the substrate is loaded / unloaded into / from the processing bath, the pressure in the processing bath is set to be almost atmospheric pressure. Therefore, the loading / unloading port is opened. Also, it is possible to prevent the gas inside the processing tank from flowing out and the outside gas from flowing into the processing tank.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention. FIG. 1 shows a spin processing apparatus, which has a box-shaped processing tank 1. A cup body 2 is arranged in the processing tank 1. The cup body 2 is composed of a lower cup 3 provided on the bottom plate of the processing tank 1 and an upper cup 4 provided on the lower cup 3 so as to be vertically movable by a vertical drive mechanism (not shown).

A plurality of discharge pipes 5 are connected to the bottom wall of the lower cup 3 at predetermined intervals in the circumferential direction. These discharge pipes 5
Communicates with the exhaust pump 6. The exhaust pump 6 is controlled by the control device 7 in terms of start / stop and rotation speed.

A base plate 8 is arranged on the lower surface side of the cup body 7. The lower plate 3 is attached to the base plate 8.
A mounting hole 9 is formed at a position corresponding to. An upper end of a stator 12 of a control motor 11 which constitutes a driving means is fitted and fixed in the mounting hole 9.

The stator 12 has a cylindrical shape, and a cylindrical rotor 13 is also rotatably fitted therein. The upper end surface of the rotor 13 has a cylindrical connecting body 14
Is fixed integrally by contacting the lower end surfaces. A flange portion 15 having a diameter larger than the inner diameter of the stator 12 is formed at the lower end of the connecting body 14. The flange portion 15 is slidably in contact with the upper end surface of the stator 12, whereby the rotor 1 can be rotated without blocking the rotation of the rotor 13.
3 is prevented from falling out of the stator 12.

A through hole 3a is formed in the lower cup 3 at a portion corresponding to the rotor 13, and the connecting body 14 projects into the cup body 2 through the through hole 3a. A rotary table 16 is attached to the upper end of the connecting body 14.
Around the periphery of the rotary table 16, a predetermined interval is provided in the circumferential direction.
In this embodiment, 6 at 60 degree intervals (only 2 shown)
The cylindrical holding member 17 is rotatably provided by a drive mechanism (not shown).

A support pin 18 having a tapered surface is provided on the upper end surface of the holding member 17 at a position eccentric from the rotation center of the holding member 17. A semiconductor wafer W as a substrate is supplied to the rotary table 16 so that the lower surface of the peripheral edge portion abuts the tapered surface of the support pin 18. If the holding member 17 is rotated in that state, the support pin 1
Since 8 rotates eccentrically, the semiconductor wafer W supplied to the rotary table 16 is held by the support pins 18.

The rotary table 16 has a turbulent flow prevention cover 2
Covered by 1. The turbulent flow prevention cover 21 has an outer peripheral wall 22 that covers the outer peripheral surface of the rotary table 16 and an upper surface wall 23 that covers the upper surface. The outer peripheral wall has a small diameter portion 22a on the upper side and a large diameter portion 22b on the lower side. Has been done.

The upper surface of the upper cup 4 is open, and the inner peripheral surface thereof is provided with a ring-shaped member 25 which constitutes a flow rate adjusting means with the small diameter portion 22a of the turbulent flow prevention cover 21.

When the unprocessed semiconductor wafer W is supplied to the rotary table 16 or the dried semiconductor wafer W is taken out, the upper cup 4 is lowered as described later.

When the upper cup 4 descends, the ring-shaped member 25 moves to the turbulent flow prevention cover 21 as shown in FIG.
The flow path 26 is formed so as to face the small-diameter portion 22a at a predetermined interval G and a length L. The flow path 26 has a flow path resistance determined by the gap G and the length L, and the gas supplied to the processing tank 1 in accordance with the flow path resistance passes through the cup body 2 and the exhaust pump. The flow rate discharged by 6 can be adjusted.

An opening 31 is formed in the upper wall of the processing tank 1. ULPA or HEPA is provided in this opening 31.
And a fan / filter unit 32 are provided. The fan / filter unit 32 further purifies the air in the clean room and introduces it into the processing tank 1. The amount of the clean air introduced controls the drive unit 33 of the fan / filter unit 32 by the controller 7. It is supposed to be done. That is, the drive unit 33
By controlling the number of rotations of the fan (not shown) of the fan / filter unit 32, the amount of clean air supplied into the processing tank 1 can be controlled.

When the upper cup 4 of the cup body 2 descends and the flow path 26 is formed by the ring-shaped member 25 provided on the upper cup 4 and the small diameter portion 22a of the turbulence prevention cover 21,
Due to the resistance of the flow path 26, the flow rate of gas exhausted through the exhaust pipe 5 by the exhaust pump 6 decreases.

With the upper cup 4 lowered,
As shown in FIG. 2, when the flow rate of the clean air supplied from the fan / filter unit 32 into the processing tank 1 is Q ₁ and the flow rate of the gas discharged from the cup body 2 by the exhaust pump 6 is Q ₂ , The cross-sectional area of the flow path 26 is set so that Q ₁ = Q ₂ .

That is, when the upper cup 4 descends to form the flow path 26, the flow path 26 reduces the discharge amount of the clean air supplied from the fan / filter unit 32 into the processing tank 1. In a state where the cup body 4 is raised, Q ₁ <Q ₂ is set, and the cup body 4 is lowered to move to the flow path 2
When 6 is formed, the resistance of the flow path 26 causes Q
_The flow rates Q ₁ and Q ₂ are set so that ₁ = Q ₂ .

By setting Q ₁ <Q ₂ when the upper cup 4 of the cup body 2 is rising, the inside of the processing tank 1 is maintained at a negative pressure.

An inlet / outlet opening 34 is formed on one side of the processing tank 1. The inlet / outlet port 34 is used as the processing tank 1.
It is opened and closed by a shutter 35 provided on one side so as to be vertically slidable. The shutter 35 is driven by a cylinder 36 that operates with compressed air. That is,
A control valve 37 for controlling the flow of compressed air is provided in the cylinder 36, and the shutter 35 can be moved up and down by switching the control valve 37 by the control device 7. .

A cylindrical fixed shaft 41 is inserted into the rotor 13 of the control motor 11. A nozzle head 43 is provided at the upper end of the fixed shaft 41 so as to project from the through hole 42 formed in the rotary table 16 to the upper surface side of the rotary table 16. The nozzle head 43 is provided with a pair of nozzles 44 for injecting a chemical liquid as a processing liquid and pure water toward the lower surface of the semiconductor wafer W held on the rotary table 16.

An opening 45 is formed on the upper wall 23 of the turbulent flow prevention cover 21 so as to face the nozzle head 43, and the processing liquid sprayed from the nozzle by the opening 45 is applied to the lower surface of the semiconductor wafer W. It is reachable.

An upper nozzle body 46 is arranged above the semiconductor wafer W held on the rotary table 16. The processing liquid is supplied from the upper nozzle body 46 to the upper surface of the semiconductor wafer W.

Next, the operation of the spin processing apparatus having the above structure will be described.

By operating the fan / filter unit 32 to supply the clean air into the processing tank 1 and operating the exhaust pump 6, the clean air supplied from the fan / filter unit 32 into the processing tank 1 will be described. Is discharged from the discharge pipe 5 through the inside of the cup body 2.

When the upper cup 4 of the cup body 2 is raised, the flow rate Q _{1 of} clean air supplied from the fan / filter unit 32 and the flow rate Q _{2 of} clean air discharged by the exhaust pump 6 are Q ₁ <Q ₂ is set, whereby negative pressure is maintained in the processing tank 1.

When the rotary table 16 is rotated while the negative pressure in the processing tank 1 is maintained and the semiconductor wafer W held on the rotary table 16 is processed by the processing liquid,
By rotating the rotary table 16 at a higher speed than during processing with the processing liquid, a drying process for removing the processing liquid adhering to the semiconductor wafer W is performed.

After the drying process, if the rotary table 16 is stopped, the upper cup 4 of the cup body 2 is lowered, and a small diameter of the ring-shaped member 25 and the turbulence prevention cover 21 provided on the inner peripheral surface of the upper cup 4. A flow path 26 having a predetermined cross-sectional area is formed with the outer peripheral surface of the portion 22a, and then the shutter 35 is lowered to open the access port 34.

When the flow path 26 is formed by lowering the upper cup 4, the resistance of the flow path 26 reduces the amount of gas discharged by the exhaust pump 6. It allows fans
Supply amount Q ₁ of clean air from the filter unit 32,
The exhaust amount Q ₂ discharged through the cup body 2 by the exhaust pump 6 becomes substantially equal.

As a result, the pressure in the processing tank 1 becomes almost atmospheric pressure, so that the atmosphere containing mist in the processing tank 1 flows out to the outside through the opened inlet / outlet port 34, or the outside air containing particles is discharged into the processing tank. 1 can be prevented from flowing into the inside.

In the above-described embodiment, the flow passage 26 formed by the ring-shaped member 25 provided in the upper cup 4 is set to have a predetermined cross-sectional area so that the processing tank can be opened when the inlet / outlet port 34 is opened. Although the pressure in 1 is set to be almost atmospheric pressure, it is also possible to control the pressure in the processing tank 1 to be atmospheric pressure by opening the inlet / outlet port 34 by other means.

For example, when the cylinder 36 is driven to open the inlet / outlet port 34, the controller 7 controls the fan / filter unit 32 to supply the clean air Q.
The rotational speeds of these may be controlled so that ₁ and the exhaust amount Q _{2 of} the exhaust pump 6 become equal.

Further, in the structure in which the ring-shaped member 25 is provided on the upper cup 4 and the flow path 26 is formed when the upper cup 4 is lowered, the cleaning by the fan / filter unit 32 is performed when the inlet / outlet opening 34 is opened. Air supply Q
The rotational speeds of these may be controlled so that ₁ and the exhaust amount Q _{2 of} the exhaust pump 6 become equal.

In the first embodiment described above, the small diameter portion 22a and the large diameter portion 22b are formed in the turbulent flow prevention cover 21, and the small diameter portion 22a and the ring provided on the upper cup 4 when the upper cup 4 is lowered. Although the flow path 26 is formed by the shape member 25, the turbulent flow prevention cover 21 has a straight shape with no change in outer dimension over the entire length in the height direction as in the second embodiment shown in FIG. Alternatively, when the upper cup 4 descends, the flow passage 26 may be formed by the outer peripheral surface 25a of the turbulent flow prevention cover 21 and the ring-shaped member 25 provided on the upper cup 4.

Further, in each of the above-described embodiments, the case where the turbulent flow prevention cover 21 is provided on the rotary table 16 to form the flow path 26 has been described. The flow path 26 may be formed by the outer peripheral surface of the table 16 and the ring-shaped member 25.

Furthermore, the resistance of the flow path 26 may be adjusted by making the ring-shaped member 26 provided on the upper cup 4 removable and replaceable with a member having a different length and inner diameter.

4 and 5 show a third embodiment of the present invention, which is a modification of the second embodiment. In the third embodiment, when the upper cup 4 is lowered, the discharge route of the clean air supplied from the fan / filter unit 32 into the processing tank 1 can be changed.

That is, on the peripheral wall of the lower cup 3, a plurality of first through holes 5 having a predetermined interval in the circumferential direction and having a predetermined size.
1 (only one is shown) are formed at substantially equal intervals in the circumferential direction, and a first through hole 5 is formed in the circumferential wall of the upper cup 4 in the circumferential direction.
A plurality of second through holes 52 are formed at positions corresponding to 1.

When the upper cup 4 is raised as shown in FIG. 4, the first through hole 51 and the second through hole 52 are not opposed to each other, but when the semiconductor wafer W is taken in and out. Figure 5
When the upper cup 4 is lowered as shown in FIG. 5, the second through hole 52 formed in the upper cup 4 faces the first through hole 51.

According to this structure, as shown by the arrow in FIG. 4, the loading / unloading port 34 is closed by the shutter 35, the upper cup 4 is raised, and the first through hole 51 and the second through hole 52 are provided. When is not opposed to each other, the clean air supplied from the fan / filter unit 32 into the processing tank 1 passes through the gap between the inner peripheral surface of the upper cup 4 and the outer peripheral surface of the turbulence prevention cover 21. And is discharged from the discharge pipe 5. At this time, very little or almost no clean air is discharged from the second through hole 52 of the upper cup 4 through the second through hole 52 of the lower cup 3.

As shown in FIG. 5, when the loading / unloading port 34 is opened and the upper cup 4 is lowered in order to load / unload the semiconductor wafer W, the second through hole 52 faces the first through hole 51. The inner peripheral surface of the ring-shaped member 25 of the upper cup 4 and the outer peripheral surface of the small diameter portion 22a of the turbulent flow prevention cover 21 face each other with a slight gap.

The flow path resistance of the pair of through holes 51, 52 facing each other is such that the distance between the inner peripheral surface of the ring-shaped member 25 of the upper cup 4 and the outer peripheral surface of the small diameter portion 22a of the turbulence prevention cover 21 is made. It becomes smaller than the flow path resistance. It allows fans
Most of the clean air supplied from the filter unit 32 into the processing tank 1 is discharged from the discharge pipe 5 through the pair of through holes 51 and 52 facing each other as shown by the arrow in the figure.

The flow path resistance when the first and second through holes 51, 52 face each other can be set relatively easily and precisely by the size and number of these through holes. Processing tank 1 for loading and unloading semiconductor wafer W
It becomes easy to maintain the internal pressure at atmospheric pressure.

When loading / unloading the semiconductor wafer W, first,
The upper cup 4 is lowered to move the first through hole 51 and the second through hole 5 to each other.
2, and clean air supplied into the processing tank 1 is discharged to the discharge pipe 5 through the facing first and second through holes.

At the same time, the controller 7 adjusts the discharge amount from the exhaust pipe 5 and the supply amount from the fan filter unit 32 to maintain the pressure in the processing tank 1 at atmospheric pressure. After that, by opening the shutter 35 and taking the semiconductor wafer W in and out, it is possible to reliably prevent the outside air from flowing into the processing tank 1. Such a procedure is the same in the first and second embodiments.

In the third embodiment, when the upper cup 4 is lowered, the resistance of the distance between the ring-shaped member 25 and the outer peripheral surface of the turbulence prevention cover 21 is sufficiently large, that is, narrowed. Is desirable. As a result, most of the clean air supplied into the processing bath 1 at the time of loading and unloading the semiconductor wafer W can be discharged through the first and second through holes 51 and 52 located opposite to each other. It becomes easy to adjust the pressure.

In the third embodiment, the turbulent flow prevention cover may have a shape having a large diameter portion and a small diameter portion as in the first embodiment.

[0063]

As described above, according to the present invention, the inlet / outlet port of the processing tank is opened so that the pressure in the processing tank is substantially atmospheric pressure when the substrate is loaded / unloaded into / from the processing tank.

Therefore, even if the loading / unloading port is opened for loading / unloading the substrate, it is possible to prevent the gas in the processing bath from flowing out and the external gas from flowing into the processing bath.

[Brief description of drawings]

FIG. 1 is a sectional view of a schematic configuration of a spin processing apparatus showing a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a part of a flow path formed when the upper cup is lowered.

FIG. 3 is an enlarged view showing a part of a flow path formed when the upper cup is lowered showing the second embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a part of a cup body in a state where an upper cup is raised showing a third embodiment of the present invention.

5 is an enlarged sectional view showing a part of the cup body in a state where the upper cup shown in FIG. 4 is lowered.

[Explanation of symbols]

1 ... Treatment tank 2 ... Cup body 3 ... Lower cup 4 ... Upper cup 7 ... Control device 11 ... Control motor 16 ... Rotary table 21 ... Turbulent flow prevention cover 25 ... Ring-shaped member 26 ... Flow path 32 ... Fan / filter unit 34 ... Entrance / exit 35 ... Shutter

Claims (5)

[Claims] 1. A spin processing apparatus for performing processing with a processing liquid and processing for removing the processing liquid while rotating a substrate, and a processing tank provided with an inlet / outlet for loading / unloading the substrate opened / closed by a shutter, and the processing tank. A cup body provided in the cup body, a rotary table provided in the cup body and driven to rotate while holding the substrate, and a fan filter provided in the upper part of the processing tank for introducing clean air into the processing tank. A unit, a discharge means for discharging the clean air supplied from the fan / filter unit into the processing bath through the cup body, and the processing for loading and unloading the substrate into the processing bath by opening the loading / unloading port. Adjust the flow rate of the clean air supplied into this treatment tank and the flow rate of the clean air discharged from the cup body so that the pressure in the tank becomes almost atmospheric pressure. A spin processing apparatus comprising: a flow rate adjusting unit for controlling. 2. The cup body includes a lower cup and an upper cup that is vertically movable with respect to the lower cup, and the flow rate adjusting means is provided when the substrate is taken in and out of the processing bath. 2. The spin processing apparatus according to claim 1, wherein the flow path is formed by the inner peripheral surface of the upper cup and the outer peripheral surface of the rotary table when the upper cup is lowered. 3. The cup body includes a lower cup and an upper cup that is vertically movable with respect to the lower cup, and the flow rate adjusting means is provided in the lower cup and the upper cup, respectively. Having a first through hole and a second through hole formed,
The spin processing apparatus according to claim 1, wherein the first and second through holes are in a non-opposing state when the upper cup is raised and face each other when the upper cup is descending. 4. The flow rate adjusting means is a control device for controlling an amount of clean air supplied into the processing tank by the fan / filter unit and an amount of air discharged from the cup body by the discharging means. The spin processing apparatus according to claim 1 or 2, wherein the spin processing apparatus is provided. 5. A spin processing method for performing a treatment with a treatment liquid and a treatment for removing the treatment liquid while rotating a substrate in a treatment tank having an inlet / outlet opening / closed by a shutter on one side. A spin processing method, wherein the pressure in the processing tank is set to substantially atmospheric pressure when the substrate is put into and taken out of the processing tank with the mouth opened.