KR20050066752A - Method and apparatus for fabricating flat panel display - Google Patents

Abstract

The present invention relates to a method and apparatus for manufacturing a flat panel display device capable of performing a patterning process without using a photo process and increasing the patterning efficiency.

An apparatus for manufacturing a flat panel display device according to the present invention includes a substrate coated with an etch resist; A soft mold for patterning the etch resist; A chamber in which the substrate is loaded in any one of the upper space and the lower space and separated into an upper space and a lower space by the soft mold; The soft mold and the substrate may be contacted and separated by adjusting the pressure of the upper space and the lower space.

Description

Method and apparatus for manufacturing flat panel display device {Method And Apparatus For Fabricating Flat Panel Display}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display device, and more particularly, to a method and apparatus for manufacturing a flat panel display device capable of performing a patterning process without using a photo process and increasing patterning efficiency.

In today's information society, display elements are more important than ever as visual information transfer media. Cathode ray tubes or cathode ray tubes, which are currently mainstream, have problems with weight and volume.

The flat panel display device includes a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an electroluminescence (EL). Most are commercially available and commercially available.

Liquid crystal display devices can meet the trend of light and short and short of electronic products and mass production is improving, and are rapidly replacing cathode ray tubes in many applications.

In particular, an active matrix type liquid crystal display device that drives a liquid crystal cell by using a thin film transistor (TFT) has the advantages of excellent image quality and low power consumption. It is rapidly developing in size and high resolution.

As shown in FIG. 1, the liquid crystal display includes a color filter array substrate 10 and a thin film transistor array substrate 20 bonded together with a liquid crystal layer 8 interposed therebetween.

The liquid crystal layer 8 is rotated in response to an electric field applied to the liquid crystal layer 8 to adjust the amount of light transmitted through the thin film transistor array substrate 20.

The color filter array substrate 10 includes a color filter 4 and a common electrode 6 formed on the rear surface of the upper substrate 1. The color filter 4 includes color filters of red (R), green (G), and blue (B) colors to allow color display by transmitting light of a specific wavelength band. A black matrix 2 is formed between the color filters 4 of adjacent colors to absorb the light incident from the adjacent cells, thereby preventing the lowering of the contrast.

The thin film transistor array substrate 20 includes a data line 18 and a gate line 12 formed on the lower substrate 21 to cross each other, a thin film transistor 16 formed at an intersection thereof, a thin film transistor 16 and a thin film transistor 16. The connected pixel electrode 14 is provided.

The thin film transistor 16 selectively supplies the data signal from the data line 18 to the pixel electrode 14 in response to the gate signal from the gate line 12. To this end, the thin film transistor 16 has a drain facing the source electrode with the gate electrode connected to the gate line 12, the source electrode connected to the data line 18, the channel portion included in the active layer and the ohmic contact layer interposed therebetween. It consists of electrodes.

The pixel electrode 14 is positioned in a cell region divided by the data line 18 and the gate line 12 and is made of a transparent conductive material having high light transmittance. The pixel electrode 14 generates a potential difference from the common electrode 6 by the data signal supplied via the data line and the thin film transistor 16. Due to this potential difference, the liquid crystal layer 8 located between the lower substrate 21 and the upper substrate 1 is rotated by dielectric anisotropy. Accordingly, light supplied from the light source via the pixel electrode 14 is transmitted toward the upper substrate 1.

Meanwhile, the manufacturing process of the liquid crystal display shown in FIG. 1 is divided into a substrate cleaning process, a substrate patterning process, an alignment film forming / rubbing process, a substrate bonding / liquid crystal injection process, a mounting process, an inspection process, a repair process, and the like. .

In the substrate cleaning process, foreign substances contaminated on the surface of the substrate of the liquid crystal display device are removed with the cleaning liquid. The substrate patterning process is divided into a patterning process of a color filter array substrate and a patterning process of a thin film transistor array substrate. In the alignment film forming / rubbing process, an alignment film is applied to each of the color filter array substrate and the thin film transistor array substrate, and the alignment film is rubbed with a rubbing cloth or the like. In the substrate bonding / liquid crystal injection process, a color filter array substrate and a thin film transistor array substrate are bonded together using a sealant, a liquid crystal and a ball spacer are injected through the liquid crystal injection hole, and then the liquid crystal injection hole is sealed. The mounting process connects a tape carrier package on which an integrated circuit such as a gate drive integrated circuit and a data drive integrated circuit is mounted, to a pad portion on a substrate. Such a drive integrated circuit may be directly mounted on a substrate by a chip on glass method in addition to the tape automated bonding method using the tape carrier package described above. The inspection process includes electrical inspection performed after signal lines such as data lines and gate lines and pixel electrodes are formed on the thin film transistor array substrate, and electrical inspection and visual inspection performed after the substrate bonding / liquid crystal injection process. The repair process restores the substrate that is determined to be repairable by the inspection process. Non-repairable substrates are discarded in the inspection process.

In the method of manufacturing a flat panel display device including the liquid crystal display device, the substrate patterning process is a process of patterning a thin film material laminated on the substrate by a photolithography process. This photolithography process is a series of photolithography processes including the application of photoresist, mask alignment, exposure, development and stripping. This photolithography process has a long process time, a large waste of photoresist and strip solution for removing the photoresist pattern, and requires expensive equipment such as exposure equipment. In particular, as the size of the substrate becomes larger and the pattern size becomes smaller, the price of the exposure equipment increases.

Accordingly, an object of the present invention is to provide a method and apparatus for manufacturing a flat panel display device capable of performing a patterning process without using a photo process and increasing the patterning efficiency.

In order to achieve the above object, the apparatus for manufacturing a flat panel display device according to the present invention comprises a substrate coated with an etch resist; A soft mold for patterning the etch resist; A chamber in which the substrate is loaded in any one of the upper space and the lower space and separated into an upper space and a lower space by the soft mold; The soft mold and the substrate may be contacted and separated by adjusting the pressure of the upper space and the lower space.

The apparatus for manufacturing a flat panel display device includes a gas supply unit for injecting gas into each of the upper space and the lower space; An exhaust pump for exhausting the gas injected into the upper space and the lower space; And an alignment sensing unit for sensing alignment between the soft mold and the substrate.

The substrate is characterized in that it is loaded in the lower space.

When the pressure of the lower space is lower than the pressure of the upper space, the substrate and the soft mold is characterized in that the contact.

When the pressure of the lower space is greater than the pressure of the upper space, the substrate and the soft mold is characterized in that the separation.

In order to achieve the above object, a method of manufacturing a flat panel display device according to the present invention comprises the steps of preparing a substrate coated with etch resist; Providing a soft mold for patterning the etch resist; Loading the substrate into any one of the upper space and the lower space of the chamber separated by the soft mold into an upper space and a lower space; And adjusting the pressure of the upper space and the lower space such that the soft mold and the substrate are in contact with and separated from each other.

The loading of the substrate into any one of the upper space and the lower space of the chamber separated by the soft mold into the upper space and the lower space may be performed on the susceptor moved by a vacuum chuck positioned in the lower space. Loading; And detecting the accuracy of alignment of the soft mold with the substrate.

Loading the substrate into any one of the upper space and the lower space of the chamber separated by the soft mold into the upper space and the lower space includes placing the substrate in the lower space such that the soft mold and the substrate are spaced several hundred μm apart. It characterized in that it comprises the step of loading.

Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated, the pressure of the lower space is adjusted to be lower than the pressure of the upper space to contact the substrate and the soft mold And forming the patterned etch resist pattern.

Adjusting the pressure of the upper space and the lower space such that the soft mold and the substrate can be contacted and separated, the step of adjusting the pressure of the lower space lower than the pressure of the upper space by injecting gas into the upper space Characterized in that it comprises a.

Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated, the substrate formed with the etch resist pattern formed by adjusting the pressure of the lower space is greater than the pressure of the upper space; It characterized in that it comprises the step of separating the soft mold.

Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated, the step of injecting gas into the lower space so that the pressure of the lower space is above the pressure of the upper space. Characterized in that it comprises a.

Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated, so as to exhaust the gas injected into the upper space so that the pressure of the lower space is above the pressure of the upper space. Characterized in that it comprises a step.

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 8C.

2 is a view illustrating a method of manufacturing a flat panel display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a method of manufacturing a flat panel display device according to an exemplary embodiment of the present invention may include applying an etch resist solution 33a onto a glass substrate 31 on which a thin film 32a of a pixel array is formed. Patterning process of etch resist solution 33a using soft mold 34, etching process for patterning thin film 32a, strip process of etch resist pattern 33b, and inspection process for thin film pattern 32b. do.

The thin film 32a of the pixel array formed on the glass substrate 31 is a basic material used as a metal pattern, an organic pattern, and an inorganic pattern present in the pixel array of the flat panel display element. The glass substrate is formed by a known coating process or a deposition process. It is formed on (31).

The etch resist solution 33a may be a material having heat resistance and chemical resistance, such as a solution in which about 5 to 30 wt% of Novolac resin is added to an ethanol solution. The etch resist solution 33a is applied onto the thin film 32a by a coating process such as nozzle spraying or spin coating.

The soft mold 34 has grooves 34a corresponding to the pattern to be formed on the glass substrate 31. After the soft mold 34 is aligned on the etch resist solution 33a, the soft mold 34 is pressurized to the etch resist solution 33a only at a pressure such that contact with the thin film 32a is possible, that is, at its own weight. At the same time, the glass substrate 31 is baked at a temperature of about 130 ° C. or less for about 10 minutes to 2 hours. Then, the etch resist solution 33a is formed by the capillary force generated by the pressure between the soft mold 34 and the glass substrate 31 and the repulsion force between the soft mold 34 and the etch resist solution 33a. As shown in FIG. 3, it moves into the groove 34a of the soft mold 34. As a result, the etch resist pattern 33b is formed on the thin film 32a in the form of the groove pattern of the soft mold 34 and the pattern reversely transferred.

After the soft mold 34 and the glass substrate 31 are separated, a wet etching process or a dry etching process may be performed. At this time, since the etch resist pattern 33b serves as a mask, only the thin film 32a positioned below the etch resist pattern 33b remains on the glass substrate 31 and the other thin films 32a are removed to form the thin film pattern. 32b is formed. Subsequently, the etch resist pattern 33b is removed by a strip process, and short, disconnection, etc. of the thin film pattern 32b are inspected through electrical and optical inspection of the thin film pattern 32b.

The soft mold 34 is separated from the glass substrate 31 and then washed with ultraviolet (UV) and ozone (O ₃ ), and then re-injected into another patterning process of the thin film 32a.

However, in the patterning process of the etch resist, the etch resist solution 33a is caused by the outgassing generated by the volatile solvent in the etch resist solution 33a and the outside air introduced into the etch resist solution 33a. Bubbles may be generated within That is, as shown in FIG. 4, fine bubbles 41 exist in the etch resist solution 33a and air in the air is mixed into the etch resist solution 33a upon contact of the soft mold 34 and the etch resist solution 33a. do. Bubbles in the etch resist solution 33a are increased in the pressure and baking process due to the pressurization of the soft mold 34 and the bubbles act as a cause of depression or loss of the etch resist pattern 33b.

Bubbles generated during the etch resist pattern process are faster than the ability of the soft mold 34 to solidify while absorbing the solvent in the etch resist solution 33a, so the evaporation rate of the solvent is faster than that of the etch resist solution 33a and the etch resist pattern 33b. ) And a pattern defect of the etch resist pattern 33b.

In the case where the thin film pattern 32b is a signal wiring, an unwanted short or open exists due to the pattern defect of the etch resist pattern 33b, and thus the signal supply to the display device cannot be normally performed.

In addition, the soft mold 34 is pressed against the etch resist solution 33a at a pressure such that the thin film 32a formed on the substrate 31 and the soft mold 34 are in contact with each other. At this time, the soft mold 34 should be uniformly pressed over the entire area of the etch resist solution 33a. However, the larger the size of the substrate 31 (for example, when the long side of the substrate is 1500 mm or more), the lower the uniformity of the pressure applied to the etch resist solution 33a.

In order to prevent the pattern defect of the etch resist caused by residual bubbles and to uniformize the pressure applied to the etch resist solution, the method and apparatus for manufacturing a flat panel display device according to the present invention are separated from the first and second seals based on the soft mold. The pressure difference of the space is used to contact / disengage the soft mold in front of the substrate.

5 is a cross-sectional view showing an apparatus for manufacturing a flat panel display element according to the present invention.

Referring to FIG. 5, the apparatus for manufacturing a flat panel display device according to the present invention includes a fixing part 110 for fixing the soft mold 102 and a first and second sealed space P1 with the soft mold 102 therebetween. And upper and lower frames 112 and 114 for providing P2, a gas supply unit 118 and an exhaust pump 120 for adjusting internal pressures of the first and second sealed spaces P1 and P2.

The fixing part 110 fixes the soft mold 102 at both sides to prevent the soft mold 102 from bending. To this end, the fixing part 110 has grooves 128 into which both sides of the soft mold 102 are inserted.

At least one alignment detector 108 is installed on the upper frame 112 to sense the accuracy of the alignment of the soft mold 102 and the substrate 104. The upper frame 112 is formed to face the soft mold 102 fixed by the fixing part 110 to provide a second sealed space P2.

The susceptor 106 having the substrate 104 on which the thin film and the etch resist solution are sequentially formed is formed on the lower frame 114. The susceptor 106 is moved in the x, y, z, and θ directions by the vacuum chuck 116. That is, the vacuum chuck 116 moves the position of the susceptor 106 in a predetermined direction so as to align the soft mold 102 with the substrate 104 seated on the susceptor 106. The lower frame 114 is formed to face the soft mold 102 fixed by the fixing part 110 to provide a first sealed space P1.

The gas supply unit 118 injects gas into the first and second sealed spaces P1 and P2 according to whether the first and second valves V1 and V2 are opened or closed, thereby allowing the first and second sealed spaces P1 and P2 to be opened. To adjust the pressure.

The exhaust pump 120 exhausts the gas injected into the first and second sealed spaces P1 and P2 according to whether the third and fourth valves V3 and V4 are opened or closed to exhaust the first and second sealed spaces P1. , Adjust the pressure of P2).

As described above, the apparatus for manufacturing a flat panel display device according to the present invention detaches and softens the soft mold and the substrate by a pressure difference using a vacuum, thereby increasing alignment accuracy of the soft mold and the substrate and preventing bubble generation. In addition, since the soft mold and the substrate are brought into contact by the pressure difference, the soft mold can uniformly press the etch resist solution formed on the substrate over the entire area.

6 is a cross-sectional view illustrating an apparatus for manufacturing a flat panel display device according to another exemplary embodiment.

In the apparatus for manufacturing a flat panel display device illustrated in FIG. 6, at least two soft molds are connected through a connection unit 130 to one substrate 104 which is divided into at least two regions as compared with the apparatus for manufacturing a flat panel display device illustrated in FIG. 5. The same components are provided except that 102 is soft-processed. Accordingly, detailed description of the same components will be omitted.

The connecting portion 130 is formed between the first and second soft molds 102a and 102b to fix the first and second soft molds 102a and 102b as shown in FIG. 7. The connection portion 130 is formed using an adhesive. Accordingly, one side of the first and second soft molds 102a and 102b is fixed by the connection part 130, and the other one side of the first and second soft molds 102a and 102b is fixed by the groove 126 of the fixing part 110. That is, three surfaces of the substrate 104 are fixed by the fixing part 110, and one surface of the substrate 104 is fixed by the connecting part 130.

The substrate 104 is divided into at least two regions, for example, a first region A corresponding to the first soft mold 102a and a second region B corresponding to the second soft mold 102b. In this case, a thin film transistor array or a color filter array is formed in the same or different types in the first region and the second region A, B. Meanwhile, the first and second regions A and B of the substrate 104 are separated by a scribing process after forming a thin film transistor array or a color filter array, and then form at least one liquid crystal panel by a bonding process. .

As described above, an apparatus and method for manufacturing a flat panel display device according to another exemplary embodiment of the present invention may include at least two thin film transistor arrays or color filter arrays formed in the same type or different types in at least two regions of a substrate. Soft molds are used. That is, at least two soft molds are connected to each other through the connection part 130 to uniformly press the etch resist solution formed in at least two regions of the substrate.

Accordingly, there is no need to separately manufacture a soft mold that is the same as the substrate size, thereby reducing the cost. In addition, when a defect occurs in any one of the at least two soft molds, only the defective soft mold is replaced, thereby facilitating replacement of the soft mold.

8A to 8C are cross-sectional views illustrating a method of manufacturing the flat panel display device illustrated in FIGS. 5 and 7.

First, a susceptor on which the substrate 104 is seated using the vacuum chuck 116 so that the substrate 104 on which the thin film and the etch resist solution are formed and the soft mold 102 are spaced within a predetermined distance, for example, about several hundred μm. 106) is moved to a predetermined direction. Then, the alignment detection unit 108 senses alignment accuracy, including a separation distance between the substrate 104 and the soft mold 102. When the alignment is correct, the pressures of the first and second sealed spaces P1 and P2 are equalized as shown in FIG. 8A by using the gas supply unit 118 and the exhaust pump 120. For example, the pressures of the first and second sealed spaces P1 and P2 are maintained at atmospheric pressure.

Then, the vacuum degree of the second sealed space P2 is lower than the vacuum degree of the first sealed space P1 by using the gas supply unit 118 and the exhaust pump 120. That is, the pressure of the second sealed space P2 is higher than the pressure of the first sealed space P1. (P1 <P2) To this end, at least one of the first to fourth valves V1 to V4 is opened and closed. do. For example, the second sealed space is opened by injecting gas into the second sealed space P2 by opening the first valve V1 or by exhausting the gas injected into the first sealed space P1 by opening the fourth valve V4. The vacuum degree of (P2) is lowered.

As the second sealed space P2 is expanded by the pressure difference P1 <P2 between the first and second sealed spaces P1 and P2, the soft mold 102 is formed as shown in FIG. 8B. To expand). Thereafter, when the soft mold 102 reaches the desired position on the substrate 104, the first valve V1 is closed to maintain the vacuum of the second sealed space P2 for a predetermined period of time, for example, about 130 ° C. or less. 10 minutes to 2 hours.

Then, the etch resist solution is formed by the capillary force generated by the pressure between the soft mold 102 and the etch resist solution formed on the substrate 104 and the repulsive force between the soft mold 102 and the etch resist solution. ) Moves into a groove (not shown). As a result, the groove of the soft mold 102 and the etch resist pattern in the form of reverse transfer pattern are formed.

Thereafter, the pressure of the first sealed space P1 is equal to or greater than the pressure of the second sealed space P2 by using the gas supply unit 118 and the exhaust pump 120. To this end, open the second valve (V2) to inject gas into the first sealed space (P1) or open the third valve (V3) to exhaust the gas injected into the second sealed space (P2) to the first sealed space ( The pressure of P1) is formed above the pressure of the second closed space P2. Accordingly, the first sealed space P1 is expanded or the second sealed space P2 is contracted to separate the soft mold 102 and the substrate 104 as shown in FIG. 8C.

Then, the thin film pattern is formed by etching the thin film positioned below the etch resist pattern with the etch resist pattern as a mask on the substrate 104.

On the other hand, if a predetermined temperature is applied to the substrate prior to the separation process of the soft mold and the substrate, the etch resist solution formed on the substrate facilitates the movement of the soft mold into the grooves and the evaporation of the solvent contained in the etch resist solution. .

As described above, in the apparatus and method for manufacturing the flat panel display device according to the present invention, since the soft mold and the substrate are attached and detached by a pressure difference using a vacuum, the alignment accuracy of the soft mold and the substrate is increased and bubbles can be prevented. In addition, at least two soft molds may be connected to each other through a connection part to form a homogeneous or heterogeneous thin film transistor array or color filter array on the substrate. In addition, since the soft mold and the substrate come into contact with each other by the pressure difference, the soft mold can uniformly press the etch resist solution formed on the substrate over the entire area.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a perspective view showing a conventional liquid crystal display device.

2 is a view showing a method of manufacturing a flat panel display device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a movement of an etch resist solution when the soft mold illustrated in FIG. 2 contacts a substrate.

4 is a cross-sectional view showing a bubble generated during the process of FIG. 2 and a pattern defect of an etch resist generated due to the bubble.

5 is a diagram illustrating an apparatus for manufacturing a flat panel display device according to an exemplary embodiment of the present invention.

6 is a diagram illustrating an apparatus for manufacturing a flat panel display device according to another exemplary embodiment.

FIG. 7 is a view illustrating in detail the connection unit illustrated in FIG. 6.

8A through 8C are cross-sectional views sequentially illustrating a method of detaching and attaching the soft mold and the substrate illustrated in FIGS. 5 and 6.

<Description of Symbols for Main Parts of Drawings>

1,11,102: Substrate 2: Black Matrix

4 color filter 6 common electrode

8 liquid crystal layer 10 color filter array substrate

12 gate line 14 pixel electrode

16: thin film transistor 18: data line

20: thin film transistor array substrate 32a, 32b: thin film

33a, 33b: etch resist 34,104: soft mold

41: bubble 108: alignment detection unit

110: process part 112,114: frame

116: vacuum chuck 118: gas supply unit

120: exhaust pump 130: connection

Claims (13)

A substrate coated with an etch resist; A soft mold for patterning the etch resist; A chamber in which the substrate is loaded in any one of the upper space and the lower space and separated into an upper space and a lower space by the soft mold; And the soft mold and the substrate are in contact with and separated from each other by adjusting the pressure between the upper space and the lower space. The method of claim 1, A gas supply unit for injecting gas into each of the upper space and the lower space; An exhaust pump for exhausting the gas injected into the upper space and the lower space; And an alignment sensing unit for sensing alignment between the soft mold and the substrate. The method of claim 1, And the substrate is loaded in the lower space. The method of claim 3, wherein And when the pressure of the lower space is lower than the pressure of the upper space, the substrate and the soft mold contact each other. The method of claim 3, wherein And the substrate and the soft mold are separated when the pressure of the lower space is greater than or equal to the pressure of the upper space. Providing a substrate coated with etch resist; Providing a soft mold for patterning the etch resist; Loading the substrate into any one of the upper space and the lower space of the chamber separated by the soft mold into an upper space and a lower space; And adjusting the pressure of the upper space and the lower space such that the soft mold and the substrate are in contact with and separated from each other. The method of claim 6, Loading the substrate into any one of the upper space and the lower space of the chamber divided into an upper space and a lower space by the soft mold Loading the substrate onto a susceptor that is moved by a vacuum chuck positioned in the subspace; And detecting the accuracy of alignment between the soft mold and the substrate. The method of claim 6, Loading the substrate into any one of the upper space and the lower space of the chamber divided into an upper space and a lower space by the soft mold And loading said substrate into said lower space such that said soft mold and said substrate are spaced hundreds of micrometers apart. The method of claim 6, Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated And adjusting the pressure of the lower space to be lower than the pressure of the upper space to contact the substrate and the soft mold to form the etch resist patterned pattern. . The method of claim 9, Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated And injecting a gas into the upper space to adjust the pressure of the lower space to be lower than the pressure of the upper space. The method of claim 6, Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated And adjusting the pressure of the lower space to be equal to or greater than the pressure of the upper space to separate the substrate on which the etch resist pattern is formed from the soft mold. The method of claim 11, Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated And injecting a gas into the lower space such that the pressure of the lower space is equal to or greater than the pressure of the upper space. The method of claim 11, Adjusting the pressure of the upper space and the lower space so that the soft mold and the substrate can be contacted and separated And exhausting the gas injected into the upper space so that the pressure in the lower space is equal to or greater than the pressure in the upper space.