JP3604182B2 - Method and apparatus for removing excess coating liquid at end of substrate surface - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for removing an excess coating solution on an edge of a substrate surface after the application of the coating solution to a single substrate such as a large glass substrate represented by a color filter for an LCD, and an apparatus used for the method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a spin coating method is known as a method of coating a coating liquid on a single-wafer substrate such as a large glass substrate represented by a color filter for LCD.
[0003]
This method has the drawback that the coating efficiency is as low as about 10%, and the coating film thickness becomes too large at the corners of the substrate. There are knife coating, roll coating, and die coating methods that can solve this disadvantage and efficiently apply the coating liquid to a single-wafer substrate. To obtain a uniform film thickness using these methods, In addition, there is a problem that the smoothness of the substrate surface must be lower than the coating accuracy. As a solution application method that can also solve this problem, the applicant applied a method in which a coating solution bead is formed between the substrate surface and the application head, and the substrate and the application head are relatively moved to apply the application solution to the substrate surface. It was proposed earlier in International Application No. PCT / JP94 / 00845 (international application date: May 27, 1994).
[0004]
[Problems to be solved by the invention]
Even when the coating is performed using the above-described knife coating method, roll coating method, or die coating method, or when performing the coating using the method described in the international application described above, the coating end edge of the substrate at the end of the coating. An excess coating solution remains in the coating, and the remaining solution causes a reduction in the uniform area of the coating film thickness and a partial drying failure, which causes the quality of the coating film to be impaired. I have.
[0005]
Therefore, in the method disclosed in the above-mentioned international application, in order to remove the excess coating solution, the excess coating solution is removed by vacuum suction or by an absorbent roll. However, removal of the excess coating solution by vacuum suction takes a long time to process, and removal by an absorbent roll selects a roll material that has resistance depending on the type of organic solvent, especially when using an organic solvent-based coating solution. It is difficult to clean, and the solvent has high volatility, so that it is difficult to wash as compared with an aqueous system, and is mechanically complicated.
[0006]
The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a method and an apparatus for removing an excess coating solution at an edge of a substrate surface, which can remove the excess coating solution neatly in a short time. It is in.
[0007]
[Means for Solving the Problems]
The present invention is a method for removing excess coating liquid at the edge of a substrate surface, which removes excess coating liquid remaining near the edge of the substrate surface when coating of the coating liquid on the substrate surface is completed. Prior to the coating operation, only the substrate portion near the end is covered with a coating thin plate, and after the coating operation is completed, by removing the coating thin plate, a method of removing excess coating liquid remaining on the coating thin plate , A main portion having a surface continuous with the coated thin plate is formed of a porous material, and the main portion is brought close to a substrate edge adjacent to the substrate portion near the end portion, and the surface of the main portion and the coating are formed. The excess coating solution remaining on the surface of the thin plate is sucked through the porous material, and the main body is removed together with the excess coating solution attached to the surface when the coated thin plate is removed from the substrate .
[0010]
Further, the method according to the present invention is characterized in that the thin plate and the main portion are washed after the coating is completed and before the next coating operation is started.
[0011]
The apparatus for removing excess coating liquid at the edge of a substrate surface according to the present invention includes a proximity position that is brought close to an end surface of a substrate supported by the liquid coating apparatus on the side where excess coating liquid remains on the substrate when liquid is applied; A substrate covering member movably provided between a separation position separated from the substrate after completion, the substrate covering member having a covering thin plate covering the substrate surface at the end portion at a position close to the substrate covering member; Excessive application liquid adhering to the surface of the covering member at the time of application is removed by moving the covering member to the separated position, and the substrate covering member is moved to a position near the end substrate surface adjacent to the end substrate surface. Has a main body part close to, the coated thin plate and the main body part have the same plane,
The main body portion has a porous portion at a portion on the same surface as the covering thin plate, and the porous portion is connected to suction means .
[0015]
[Action]
In the method of removing excess coating liquid at the edge of the substrate surface according to the present invention, a portion near the edge of the substrate is covered with a coating thin plate before applying the coating liquid to the substrate surface, and the coating liquid is applied to the substrate surface. As a result, a coating liquid film is formed on the substrate surface including the surface of the coated thin plate, and the excess coating liquid remains on the surface of the coated thin plate. Therefore, when the coated thin plate is removed, the excess coating solution is also removed.
[0016]
Also, by applying the coating liquid to the substrate surface, the excess coating liquid also adheres to the surface of the main part having a surface continuous with the coated thin plate, so the excess coating liquid is removed by removing the coated thin plate and the main part from the substrate. You.
[0017]
In addition, since the main body is made of a porous material, an excess force can be removed from the main body surface by applying a suction force to the porous material.
[0018]
After the application, the coated thin plate and the main body are washed by the next coating operation.
[0019]
In the apparatus for removing excess coating liquid at the end of the substrate surface according to the present invention, the surface of the end of the substrate is covered with the substrate covering member by placing the substrate covering member at a close position. When the liquid is applied in this state, the coating liquid adheres to the surface of the substrate and the surface of the substrate covering member, and the excess coating liquid remains particularly on the surface of the substrate covering member. Therefore, the excess coating liquid is removed by removing the substrate covering member.
[0020]
Further , the coating liquid, particularly the excess coating liquid, adheres to the surface of the main portion provided on the substrate coating member . When the substrate coating member including the main portion is removed after the application, the excessive coating liquid is removed.
[0021]
In addition, since the coating thin plate and the main body have the same plane, the excessive coating solution is naturally attached to these planes.
[0022]
In addition, by performing suction in the porous portion, the excess coating solution adhering to the surface of the substrate covering member via the porous portion is effectively removed.
[0023]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Before that, an example of a method of applying a coating liquid to a glass substrate will be described with reference to FIGS. 1 to 4.
[0024]
The single-wafer substrate S applied by the present invention is typically a large-sized glass substrate for an LCD color filter, and a liquid applied to the substrate is a photosensitive liquid for forming a fine pattern on the glass substrate. Resin. Although the glass substrate is inflexible, the substrate processed in the present invention is not limited to such a glass substrate, but may be plastic, metal, paper, or the like, or the substrate itself may have flexibility. As the liquid to be applied, various liquids such as water-based and solvent-based liquids can be used, and pigments, dyes, fillers, sensitizers, resins, additives, and the like can be used alone or in combination.
[0025]
In FIG. 1, S is a substrate. FIG. 1 shows a state at the start of liquid application to the substrate S.
[0026]
As shown in FIG. 1, the substrate S is suction-held on the suction surface on the lower surface of the substrate holder 8 at an angle θ with respect to the horizontal. Then, the position of the holder 8 is determined so that the linear slit 13 of the coating head H is located with a certain clearance immediately below the lower surface near the highest edge S1 of the substrate S.
[0027]
The coating liquid R such as a photosensitive resin is stored in a coating liquid tank 15, is sent into the coating head H by a liquid sending means such as a pump 16, is sent upward from the slit 13, and is coated with a coating liquid bead. B is formed. The coating liquid bead B is formed as a liquid pool of the coating liquid R in a clearance between the lower surface (main surface) of the substrate S and the coating head H, and the liquid bead B adheres to the lower surface of the substrate S. The minimum clearance between the lower surface of the substrate and the coating head H is set so that the coating liquid R does not spill out of the clearance and the coating liquid bead B is formed due to physical properties such as the viscosity and the surface tension of the coating liquid R. When the coating liquid bead B is formed as shown in FIG. 1, the meniscus L ₁ that faces the lower substrate S side, while the meniscus L ₂ facing the high substrate side is formed, for the inclination angle θ In addition, the heights h ₁ and h ₂ of the meniscuses L ₁ and L ₂ satisfy h ₁ <h ₂ .
[0028]
Next, the application to the main surface, which is the lower surface of the substrate S, from the application start state in FIG.
[0029]
When the holder 8 is moved obliquely upward and rightward from the position shown in FIG. 2 along a guide rail (not shown) while maintaining the clearance constant, the substrate S is tilted from the state shown in FIG. It moves obliquely upward and to the right with respect to the coating head H at an angle θ. In parallel with this, when the coating liquid R is continuously fed to the coating head H by the coating liquid pump 16 to continuously form the beads B, the coating liquid R is sequentially attached to the main surface of the lower surface of the substrate S, and the coating layer Ra is formed. It is formed. During this coating process, the coating liquid R is supplied to the coating liquid bead B by the pump 16 so as to supplement the applied amount in order, so that the shape of the bead is kept constant. Then, as shown in FIG. 4, when the coating head H reaches the final end of the coating range near the lowest edge S2 of the substrate S, the movement of the substrate S is stopped, and then the coating head H remains in the clearance. After removing the coating liquid bead B, the coating head H is separated to a place where the substrate S is not hindered, if necessary.
[0030]
Thereafter, the coating film Ra is dried using a drying means such as a hot plate, hot air, or a far-infrared heater in a drying unit with the substrate S horizontally or upward or downward to form a uniform coating film.
[0031]
The method of applying the liquid to the substrate as described above is basically described in the applicant's international application PCT / JP94 / 00845.
[0032]
When the coating liquid film Ra is formed on the surface of the substrate S as described above, the excess coating liquid Rb remains near the lower edge S2 of the substrate S as shown in FIG. Such accumulation of the excess coating liquid Rb also occurs when the coating liquid film Ra is formed using a method other than the methods shown in FIGS. For example, the same problem occurs when a coating liquid film is formed on a substrate surface by a roll coater, an extrusion coater, or the like. The present invention is intended to reliably remove such residual excess coating solution.
[0033]
FIG. 5 shows an embodiment of the apparatus of the present invention for removing the residual excess coating solution. In the figure, reference numeral 1 denotes a coating liquid application device having the same operation principle as shown in FIGS. 1 to 4, and shows a case where the inclination angle θ shown in FIG. 1 is zero or nearly zero. The substrate holder 8 is pivotally supported by the shaft 2 so that the tilt angle θ can be adjusted and the substrate holder 8 can be turned upside down. The substrate S is held on the lower surface of the holder 8, and the film Ra of the coating liquid is already formed on the lower surface of the substrate S.
[0034]
A coating head H is provided below the holder 8. The coating head H has a linear slit 13 for sending the coating liquid upward in exactly the same principle as that shown in FIG. In the case of FIG. 1, the substrate S is configured to move with respect to the coating head H. However, in the example of FIG. 5, the substrate S supported by the holder 8 does not move, and the coating head H moves left and right. To move to. In the present invention, one of the substrate S and the coating head H only needs to move with respect to the other, and which one to move is arbitrary.
[0035]
The coating head H is supported on a table 3, and the table 3 is supported on a horizontal moving table 5 via a first moving means, that is, a vertical moving mechanism 4. The nut 6 of the moving table 5 is screwed to a feed screw 7 rotatably supported on a base 11. The feed screw 7 is driven to rotate by a servo motor M. Therefore, the movable base 5 moves in the left-right direction by the operation of the servo motor M. The feed screw 7, the nut 6, and the servomotor M constitute a second moving means, that is, a horizontal moving mechanism.
[0036]
The coating head H is a block-shaped member having a length corresponding to the coating width on the surface of the substrate S. On the upper surface thereof, a coating liquid R sent from a coating liquid tank 15 shown in FIG. Are formed in the longitudinal direction of the coating head H. The bottom of the slit 13 is connected to the pump 16 by a suitable connecting means.
[0037]
In FIG. 5, reference numeral 20 denotes a substrate covering member which is a feature of the present invention. The substrate covering member 20 is rotatably driven by the tip of a piston rod 22 of a moving mechanism 21 such as an air cylinder provided on a base 19. It is supported and will perform the exercises described below. That is, when the moving mechanism 21 operates to extend rightward in the drawing, the substrate covering member 20 also moves rightward and reaches a position close to the edge of the substrate S held by the holder 8. Here, the substrate covering member 20 is rotated counterclockwise by an appropriate rotation driving mechanism to take a close position to the substrate S as shown in FIG. The substrate covering member 20 is composed of a covering thin plate 20a and a main body 20b integral therewith. The covering thin plate 20a and the main portion 20b have a length that covers the entire covering width of the substrate S, and their lower surfaces constitute the same plane. The main body portion 20b is a block-shaped member, and the surface 24 adjacent to the coating thin plate 20a is a contact surface that is substantially perpendicular to the surface of the coating thin plate 20a. When the substrate covering member 20 is in the proximity position shown in FIG. 6, the covering thin plate 20a comes into surface contact with the end surface of the substrate S, and the contact surface 24 comes into surface contact with the edge of the substrate S. Become like On the other hand, when the moving mechanism 21 operates in the contracting direction, the substrate covering member 20 takes the separated position shown in FIG.
[0038]
Before the coating liquid film Ra is formed on the surface of the substrate S by the coating head H as shown in FIG. 5, the covering member 20 abuts on the end of the substrate S held by the holder 8 in the state shown in FIG. In this state, the coating operation by the coating head H is performed. The application of the liquid to the surface of the substrate S is started at a position where the application head H is below the right end of the substrate S in FIG. With the coating head H raised so that the coating liquid R sent out from the slit 13 of the coating head H forms a bead B (as shown in FIG. 1) with the lower surface of the substrate S, the coating head H 5 is moved to the left in FIG. 5 by the feed screw 7, whereby the coating liquid layer Ra is formed in the same manner as shown in FIGS. The position of the coating head H indicated by a virtual line on the right side of FIG. 5 indicates a position in the middle of coating. When the application proceeds and the application head H passes the position indicated by the solid line in FIG. 5, the application is completed. The application end position is detected by a position detector (not shown) and a detection signal is output. The detection signal is input to a control device (not shown), and the vertical movement mechanism 4 of the coating head H is moved downward by a signal from the control device. To lower the coating head H.
[0039]
The coating liquid film Ra is formed as shown in FIG. 6, and the excess coating liquid Rb remains at the end as described above. However, due to the presence of the covering member 20, the excess coating solution Rb adheres from the covering thin plate 20a to the main portion 20b, and particularly adheres to the region of the main portion 20b. Next, the covering member 20 is separated from the substrate S and returned to the separated position. As a result, the substrate S is in a state where the excess coating solution Rb has been removed as shown in FIG. 7, and only the coating solution portion slightly raised at the end of the coating solution film Ra remains. The presence of the coating thin plate 20a prevents the coating liquid from flowing around the edge of the substrate S. The main body portion 20b ensures correct positioning of the covering thin plate 20a by the contact surface 24 abutting against the edge of the substrate S.
[0040]
FIG. 8 shows another embodiment. This embodiment differs from the embodiment of FIG. 6 mainly in that the main portion 20b is formed of a porous material. However, in this embodiment, the partition wall 26 is formed on the side surface of the porous material following the covering thin plate 20a, and the partition wall 27 is similarly provided behind the porous material main portion 20b. The side of the porous material main portion 20b opposite to the partition 26 is connected to a suction means (not shown) such as a vacuum pump as shown by an arrow V. As the porous material, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, acrylonitrile copolymer, ethylene-vinyl acetate copolymer, fluorine resin such as Teflon (DuPont trademark), ceramic (Al ₂ 0 ₃ System, ZrO ₂ , CaO system). The porosity of the porous material is about 50 to 85% for ceramics, and about 30 to 45% for others.
[0041]
The operation of this embodiment is substantially the same as the operation of the embodiment shown in FIG. However, in this embodiment, as shown in FIG. 8, the residual excess coating liquid Rb at the end of the coating is sucked into the main body 20b by the vacuum suction force acting on the porous main body 20b, and then is applied to the suction means. It will be sucked. Therefore, when the covering member 20 is separated from the substrate S, the problem that the excess coating liquid Rb attached to the covering member 20 drips is solved. The state of the substrate S after the excess coating liquid Rb is removed by the covering member 20 as described above is as shown in FIG. In addition, the partition walls 26 and 27 make the suction action more reliable.
[0042]
FIGS. 10 to 13 show a more specific configuration of the embodiment explained in principle with reference to FIG. 8, the same or equivalent members are indicated by the same reference numerals as those in FIG. 8, and only the different members will be described. In this specific embodiment, the porous material main portion 20b is replaced by a suction casing 30 except for a suction surface 29 thereof. And a pipe 31 connected to a suction means such as a vacuum pump is connected to the suction casing 30. The partition wall 27 constitutes a partition wall in the suction casing 30, so that a suction force effectively acts on the porous material main portion 20b. FIG. 10 shows a state during the application to the substrate S, and FIG. 11 sucks the excess application liquid Rb formed at the end of the application of the liquid into the suction casing 30 via the porous material main portion 20b. The state is shown. In the state of FIG. 12, the suction is about to end, and the suction casing 30 including the porous material main portion 20b therein is separated from the substrate S and headed to the isolated position. As can be seen from FIG. 12, by employing this configuration, most of the excess coating liquid adhering to the surface of the porous material main portion 20b disappears due to the suction force, and does not drop. As shown in FIG. 13, the suction casing 30 has a long shape in the width direction of the substrate S, and includes a plurality of pipes 31.
[0043]
In the embodiment described above, the application of the liquid to the substrate is performed on the lower surface of the substrate by using a bead. However, it is clear that the principle of the present invention can also be used for applying a liquid to the upper surface of a substrate. Also, the principles of the present invention can be used for other liquid applications that do not use beads.
[0044]
FIG. 14 shows an example in which the principle of the present invention is applied to an extrusion coater. In this example, the coating head H is sent from the right to the left with a certain clearance between the coating head H and the upper surface of the substrate S, and the coating liquid is extruded downward from the coating head H. The coating film thickness is determined by the coating speed and the liquid discharge pressure. In this example, the suction surface of the porous material main portion 20b faces upward, and the coated thin plate 20a is placed along the upper surface of the substrate S. Then, the excess coating liquid Rb remains on the upper surface of the covering member 20.
[0045]
In the above-described embodiment, the covering thin plate 20a and the main body 20b are configured to abut on the main surface and the edge of the substrate S in a surface contact state. And the main body portion 20b only needs to be close to the substrate edge.
[0046]
FIG. 15 is a graph showing a comparison between a case where a coating liquid film is formed using the principle of the present invention (shown by a black circle) and a case where the principle of the present invention is not used (shown by a black square). is there. As is apparent from this graph, when the principle of the present invention is used, the coating liquid film thickness is clearly higher than when the principle of the present invention is not used.
[0047]
【The invention's effect】
As described above, in the method for removing excess coating liquid according to the first aspect, since the vicinity of the edge of the substrate is covered with the coating thin plate and the liquid is applied including the portion of the coating thin plate, the coating is performed after the coating is completed. By separating the thin plate from the substrate, it is possible to remove excess coating liquid mainly remaining on the coated thin plate.
[0048]
In the method for removing excess coating liquid according to the second aspect, the main body is provided in addition to the coated thin plate, and the main body is brought close to the edge of the substrate. Of the coating liquid can be prevented.
[0049]
According to the excess coating liquid removing method according to the third aspect, by forming the main part with a porous material, the excess coating liquid adhering to the surface of the main part can be removed by vacuum suction through the porous material, The removal of the excess coating solution is further ensured.
[0050]
According to the method for removing excess coating liquid according to the fourth aspect, the coating thin plate and the main body can be washed using the time until the next coating step, and the next excess coating liquid removing step can be reliably performed.
[0051]
In the excess coating liquid removing apparatus according to the fifth aspect, since the vicinity of the edge of the substrate is covered with the substrate coating member and the liquid is applied including the portion of the substrate coating member, the substrate coating member is removed from the substrate after the application is completed. By separating, the excess coating liquid mainly remaining on the substrate covering member can be removed.
[0052]
In the apparatus for removing excess coating liquid according to the sixth aspect, the main body is provided on the substrate covering member and the main body is brought close to the edge of the substrate. Moreover, it is possible to prevent the coating liquid from flowing around the edge of the substrate.
[0053]
According to the apparatus for removing excess coating liquid according to the seventh aspect, the coating thin plate of the substrate coating member and the main body have the same surface, so that there is an advantage that the excess coating liquid during coating easily adheres to the surface. .
[0054]
According to the excess coating liquid removing device according to claim 8, since the main portion is formed of the porous material, the excess coating liquid adhering to the surface thereof can be removed by vacuum suction through the porous material, Excessive application liquid can be reliably removed.
[Brief description of the drawings]
FIG. 1 is a principle view showing an example of application of a coating solution to a substrate.
FIG. 2 is a diagram showing a state at the start of liquid application to a substrate.
FIG. 3 is a diagram showing a state during application.
FIG. 4 is a diagram showing a state at the time of completion of application.
FIG. 5 is a front view of an embodiment of the excess coating liquid removing apparatus according to the present invention.
6 is an enlarged view showing a state in which the substrate coating member is brought into contact with an end of the substrate and the liquid application is completed in the excess application liquid removing apparatus shown in FIG. 5;
FIG. 7 is a view showing the substrate from which the excess coating liquid has been removed by separating the substrate covering member from the state shown in FIG. 6;
FIG. 8 is a view showing an embodiment different from the example shown in FIG. 6;
FIG. 9 is a view showing a substrate from which the excess coating liquid has been removed by separating the substrate covering member from the state shown in FIG. 8;
FIG. 10 is a diagram showing an embodiment that further embodies the embodiment shown in FIG. 8;
FIG. 11 is a view showing a state in which a liquid application step in the embodiment of FIG. 10 has advanced.
FIG. 12 is a diagram showing a further advanced state of the liquid applying step in the embodiment of FIG. 10;
FIG. 13 is a side view of the suction casing shown in FIGS.
FIG. 14 is a diagram showing another embodiment to which the principle of the present invention is applied.
FIG. 15 is a coating film thickness distribution graph showing a comparison between a case where liquid coating is performed using the principle of the present invention and a case where liquid coating is performed without using the principle of the present invention.
[Explanation of symbols]
S substrate S2 substrate edge R coating liquid Ra coating liquid film Rb excess coating liquid H coating head B bead 8 substrate holder 13 coating liquid supply slit 20 substrate coating member 20a coating thin plate 20b main body 24 contact surface 26 partition wall 27 partition wall 29 suction Surface 30 Suction casing 31 Suction pipe

Claims (3)

A method for removing excess coating liquid at the edge of a substrate surface, which removes excess coating liquid remaining near the edge of the substrate surface at the end of coating of the coating liquid on the substrate surface, the method comprising: A method of removing only the excess coating liquid remaining on the coating thin plate by covering only the substrate portion near the end with the coating thin plate and removing the coating thin plate after the coating operation is completed ,
A main portion having a surface continuous with the coated thin plate is formed of a porous material, and the main portion is brought close to a substrate edge adjacent to the substrate portion near the end portion, and the surface of the main portion and the coating are formed. The excess coating solution remaining on the surface of the thin plate is sucked through the porous material, and the main body is removed together with the excess coating solution attached to the surface when the coated thin plate is removed from the substrate.
A method for removing excess coating liquid from an edge of a substrate surface . 2. The method according to claim 1, wherein the coated thin plate and the main body are washed after the coating is completed and before the next coating operation is started. Movable between a close position where the excess coating liquid of the substrate supported by the liquid coating device on the substrate surface where the excess coating liquid remains remains at the time of liquid coating and a separation position where it is separated from the substrate after liquid coating is completed The substrate coating member has a coating thin plate that covers the substrate surface at the end portion in the vicinity of the substrate coating member, and excess coating liquid that adheres to the surface of the coating member at the time of liquid application, The covering member is removed by being moved to the separated position ,
The substrate covering member has a main body portion close to a substrate edge adjacent to the end substrate surface at the proximity position,
The coated thin plate and the main body have the same plane,
An excess coating solution at an end of a substrate surface , wherein the main body portion has a porous portion at a portion on the same surface as the coated thin plate, and the porous portion is connected to suction means. Removal device.

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