JPH0780386A - Cleaning method of coating head and coating head cleaning device - Google Patents

Abstract

PURPOSE:To improve yield of the product of an object to be coated by matching a starting line of coating on a coating film and a film thickness uniformly, in a slot type fluid coating device. CONSTITUTION:A cleaning sheet 29 consisting of a non-dust cloth is run along a pipe 24 bored many through-holes 28 and the cleaning sheet 29 is made wet with a solvent supplied into the pipe 24. A tip of a coating head 2 is wiped by bringing contact the tip of the coating head 2 with the cleaning sheet 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating head cleaning method and a coating head cleaning device. Specifically, the present invention relates to a method for cleaning an application head of a slot type fluid application apparatus, and an application head cleaning apparatus for carrying out the cleaning method.

[0002]

[Background technology]

[Prior Art] In the manufacturing process of color filters for integrated circuits and liquid crystals, a coating liquid such as photoresist, filter paint, coating paint, etc. is applied on the surface of an object to be coated such as a wafer or glass substrate, and the coating liquid is about several microns. It is necessary to form a coating film having a uniform thickness. The film thickness accuracy is required to be within ± 5%, for example, but the request is becoming more and more severe.

As a method of forming such an ultrathin coating film, a spin coating method has been generally used conventionally. This method drops the coating liquid on the surface of the object to be coated,
This is a method in which a spinner spins the object to be coated at high speed to spread the coating solution thinly on the object to form a coating film having a constant film thickness determined by the number of revolutions and the like. However,
In this coating method, only a few% of the coating liquid dropped onto the coating target is coated on the surface of the coating target,
The remaining 90% or more of the excess coating liquid is discharged from the object to be coated, and the coating liquid is wasted excessively. Also,
Since the coating liquid also adheres to the side surface of the object to be coated, the coating film peeled off on the side surface of the object to be coated may adhere to the surface of the object to be coated, or the product yield decreases due to the release coating film, Alternatively, a cleaning process after coating is required.

[Slot-type fluid coating device] Therefore, as a method for improving the utilization efficiency of the coating liquid and significantly reducing the cost of the coating liquid, the applicant of the present invention has proposed a slot-type fluid coating device (slot-type fluid coating device). Type mucus spray coating device) and has been promoting its development and practical application. Some of these research results are already in Japanese Patent Application Nos. 5-154409 and 1544.
Filed as No. 10 and others.

FIG. 1 is a schematic view showing the structure of a slot type fluid coating device 1 (the structure of the device is described in detail in the specification of the above-mentioned application), in which a coating head 2 moves up and down. The coating object 3 passes under the coating head 2 while being vacuum-adsorbed on the table 4. When the coating object 3 is placed on the table 4 and sent, the measuring head 5 measures the plate thickness of the coating object 3, and the coating head 2 makes a constant measurement from the surface of the coating object 3 based on the measured value. It descends to a height with a space (several tens to several hundreds of microns) and slot 6
The coating liquid 7 having a uniform thickness is applied to the surface of the object 3 to be coated. At this time, the moving speed of the table 4 is 7
Of the coating liquid 7 discharged from the slot 6 is thinly stretched due to the speed difference with the table 4, and a very thin coating film 8 is formed on the surface of the coating object 3. . As a result, the coating liquid 7 can be applied only to a necessary area, and the amount of the coating liquid 7 used can be saved to one tenth of the conventional amount. Further, peeling of the coating film 8 attached to the side surface of the coating object 3 is eliminated.
Reference numeral 9 is a drying preventer for covering the tip of the coating head 2 while the coating head 2 is on standby and preventing the coating liquid 7 from drying at the tip of the coating head 2 in a wet atmosphere of the solvent.

FIG. 2 is a partially broken exploded perspective view showing the structure of the coating head 2 used in the fluid coating apparatus 1. The coating head 2 includes a pair of applicators 10, 1
A shim 12 having a certain thickness is sandwiched between the two, and the applicators 10, 11 and the shim 12 are integrally fastened with a bolt and a nut (not shown), and the shim is provided between the applicators 10, 11. A slot 6 having a thickness equal to the plate thickness of the shim 12 is formed by the notch portion 13 of 12,
The lower end of the slot 6 is opened as a nozzle port 14 on the lower surface of the coating head 2. In addition, one applicator 10 has a fluid reservoir 1 having a hollow shape in the width direction.
5 is provided and the fluid reservoir 15 communicates with the upper portion of the slot 6. Then, when the coating liquid 7 is injected into the coating head 2 through the coating liquid inlet 16 in the central portion, the coating liquid 7 fills and spreads in the fluid reservoir 15, and then flows out from the fluid reservoir 15 to the slot 6 and the slot 6
Is shaped into a coating liquid 7 having a constant thickness by the nozzle opening 1 at the lower end.
It is sent out from 4. At the same time, the coating liquid outlet 17
By partially discharging the coating liquid 7 in the fluid reservoir 15, the pressure distribution in the fluid reservoir 15 can be adjusted, and the film thickness of the coating film 8 can be made more uniform.

In the coating head 2, in order to prevent the coating liquid 7 from spreading around the nozzle opening 14, tapered portions 18 having a triangular cross section are projected on both sides of the nozzle opening 14 on the lower surface of the coating head 2. The entire lower surface of the coating head 2 is coated with a fluorine resin 19 such as polytetrafluoroethylene (PTFE). Looking at the tip of the tapered portion 18 in detail, as shown in FIGS. 3A and 3B, the tip of the tapered portion 18 has a width W of several hundreds of microns (for example, the width d of the slot 6 is 30 μm). On the other hand, a flat surface 20 having a width W = about 150 μm) is formed. This flat surface 20 serves to precisely position the tip of the coating head 2, that is, the tip of the tapered portion 18,
The taper portion 18 is formed by cutting for the reason that if the tip of the taper portion 18 is sharp, the wear is severe. Further, the flat surface 20 is not coated with the fluororesin 19, because the flat surface 20 has a very small width and the surface is roughened by the fluororesin processing so that the flat surface 20 cannot be obtained.

[0008]

However, when the coating liquid 7 is applied to the surface of the coating object 3 such as a glass substrate by the slot type fluid coating device 1 as described above, as shown in FIG. At the application start end and the application end end of the coating film 7, the lines 8a and 8b at the end of the coating film 8 have irregular wavy shapes in the width direction, and the coating liquid 7 rises near the end of the coating film 8 to increase the film thickness. became. In this way, the area a in which the edge of the coating film 8 is wavy or the film thickness is large needs to be cut (cut along the line C in FIG. 4) and discarded, and thus such an area a is widely spread. When it occurs, the product yield of the coating object 3 decreases. In particular, this defect was remarkable at the coating start end and was remarkable when the coating width was increased. Therefore, it is desired that the film thickness of the coating film 8 be as uniform as possible from the coating start end and that the coating start end be aligned in a substantially straight line, but it is very difficult to eliminate such a problem.

Then, as a result of investigating the cause, FIG.
As shown in (a), the coating liquid 7 is pushed out of the slot 6 due to the residual pressure at the end of coating, and hangs down at the tip of the taper portion 18 not treated with fluororesin.
Therefore, the coating start end of the coating film 8 was uneven, and the film thickness was large. Further, even if the residual pressure is removed at the end of coating, the coating liquid 7 spreads from the nozzle opening 14 to the flat surface 20 of the tapered portion 18 due to the relationship of surface tension and the like, and the coating liquid 7 adheres to the tip of the tapered portion 18. It was. For this reason, the taper portion 18 hangs down, or the coating liquid 7 that has adhered adheres non-uniformly to the object 3 to be coated at the beginning of the coating, and the coating start end becomes uneven or the film thickness increases. It was

The present invention has been made in view of the above technical background, and an object of the present invention is to make the coating start line of a slot type fluid coating apparatus uniform in film thickness with the coating start line. To provide the technology.

[0011]

A method of cleaning a coating head according to the present invention is a method for cleaning a coating head which causes a fluid to have a constant thickness and flows out of a slot before the fluid is coated, and a solvent is used. It is characterized in that the fluid adhering to the tip of the coating head is wiped by bringing the tip of the coating head into contact with the impregnated cleaning sheet.

In the method of cleaning the coating head, the tip of the coating head may be wiped while the cleaning sheet is stationary relative to the tip of the coating head. Alternatively, the tip of the coating head may be wiped while moving the cleaning sheet relative to the tip of the coating head.

Further, the coating head cleaning device according to the present invention is a coating head cleaning device for cleaning the coating head which makes the fluid have a constant thickness and flows out from the slot, and is for cleaning by contacting the tip of the coating head. It is characterized by comprising a cleaning sheet and a solvent supply means for supplying a solvent to the cleaning sheet to impregnate the cleaning sheet with the solvent.

In the coating head cleaning device, it is preferable to use a dust-free cloth as the cleaning sheet. Further, in the coating head cleaning device, the solvent supply means is constituted by a pipe capable of passing a solvent from the hollow interior toward the outer peripheral surface, and the cleaning sheet is hung around the outer peripheral surface of the pipe for cleaning. A structure in which the sheet travels on the outer peripheral surface of the pipe may be adopted.

[0015]

According to the present invention, since the cleaning sheet is impregnated with the solvent, when the tip of the coating head is brought into contact with the cloth state immediately before coating, the cleaning sheet is adhered to the coating head by the solvent that wets the cleaning sheet. The cleaning fluid is melted, and the excess fluid dissolved in the solvent is absorbed by the cleaning sheet. Therefore, the fluid adhering to the tip of the coating head can be wiped cleanly before coating, the line at the start of coating when applying to the object to be coated can be smoothly aligned, and the film at the beginning of coating The thickness can also be uniform.

Further, if the tip of the coating head is wiped while the cleaning sheet is relatively stationary with respect to the tip of the coating head, dust and dust are generated due to friction between the cleaning sheet and the coating head. It can be prevented and is suitable for use in clean rooms. Moreover, even if a dust-free cloth is used as the cleaning sheet, it is possible to prevent the generation of dust and dust, and it is suitable for use in a clean room.

On the other hand, if the tip of the coating head is wiped while moving the cleaning sheet with respect to the tip of the coating head, the coating head can be wiped by rubbing, and the excess fluid can be removed more reliably. it can.

[0018]

FIG. 5 and FIG. 6 are a sectional view and a partially cutaway plan view showing a coating head cleaning device 21 according to an embodiment of the present invention. The coating head cleaning device 21 is fixed to the front end surface of the table 4, and the cleaning device 22 of the coating head 2 is fixed in front of the coating head cleaning device 21.

First, the coating head cleaning device 21 will be described. A pipe 24 is housed in a case 23 having an open upper surface, and both ends of the pipe 24 are rotatably supported outside the case 23 via bearings 25. Has been done. Further, one end of this pipe 24 is rotatably connected to a solvent supply tube 27 via a joint 26. The pipe 24 has a large number of small through holes 28 through which a solvent can pass. The cleaning sheet 29 is, for example, a dust-free cloth such as Bencotton (trade name), a non-woven cloth, or a film having a hygroscopic property formed in a band shape or a ribbon shape. One end of the cleaning sheet 29 is wound around the rewinding roller 30 in the case 23, and the other end is wound up by the take-up roller 31 in the case 23. A motor 32 that rotates the winding roller 31 is provided. The cleaning sheet 29 is wound by a motor 32 in a direction opposite to the moving direction of the table 4 so that the peripheral speed of the outer peripheral surface of the pipe 24 becomes equal to the moving speed of the table 4, and the cleaning wound around the pipe 24 is performed. The seat 29 projects slightly above the upper surface of the case 23.

Therefore, the solvent supplied from the solvent supply tube 27 into the pipe 24 remains liquid or vaporizes and passes through the through hole 28, and is absorbed by the cleaning sheet 29 on the outer peripheral surface of the pipe 24. The cleaning sheet 29 is wetted by the solvent. On the other hand, at the start of coating, when the table 4 on which the coating object 3 such as a glass substrate is placed is sent to the coating head 2, the coating head 2
Is lowered to the height of the upper surface of the pipe 24 of the coating head cleaning device 21. Therefore, the cleaning sheet 29 wound around the outer peripheral upper surface of the pipe 24 passes under the coating head cleaning device 21 while being in contact with the tip of the coating head 2. At this time, the coating liquid 7 attached to the tip surface of the coating head 2 is washed with a solvent, and the excess coating liquid 7 attached is absorbed by the cleaning sheet 29, so that the tip (flat surface 20) of the coating head 2 is removed. It is cleanly cleaned. Further, at this time, since the cleaning sheet 29 is traveling at the peripheral speed equal to the moving speed of the table 4 in the direction opposite to the moving direction of the table 4, the cleaning sheet 29 and the coating head 2 are relatively stationary. Since the cleaning sheet 29 and the coating head 2 do not rub against each other, dust and dust are not generated, and the coating head 2 can be cleaned cleanly. Moreover, there is no fear that the tip of the coating head 2 will be worn. Furthermore, if the cleaning sheet 29 is a dust-free cloth, it is possible to further prevent the generation of dust and dust, and maintain a clean environment. Needless to say, the cleaning sheet 29 remains stationary except during cleaning.

The coating head 2 cleaned by the cleaning sheet 29 has a certain distance (several tens to several 1) from the surface of the coating object 3 measured by the measuring head 5.
00 micron) and slot 6 of coating nozzle
The fluid is caused to flow out from the coating material to form the coating film 8 on the surface of the coating object 3. At this time, since the tip end surface of the coating head 2 is wiped clean by the cleaning sheet 29 in advance, the excess coating liquid 7 attached to the outside of the slot 6 is not coated on the coating target 3, and The leading edge of the coating liquid 7 flowing out from the slot 6 is substantially flat, so that the coating start line of the coating liquid 7 can be neatly aligned. Further, the film thickness of the coating liquid 7 flowing out from the slot 6 is also made uniform, and the film thickness at the coating start end of the coating film 8 can be made uniform.

Next, the cleaning device 22 for the coating head 2 will be described. The cleaning device 22 is provided with a pair of covers 34 on the upper surface of a gutter portion 33 having a groove-shaped cross section.
Between the cover and the cover 34, a solvent discharge port 35 for discharging the solvent substantially horizontally toward the gutter part 33 is opened over the entire length of the gutter part 33. Below the solvent discharge port 35, dry air or the like is dried. A gas discharge port 36 for discharging the working gas is provided. If the coating has been suspended for a long time, the taper portion 18 of the coating head 2 is inserted into the opening 37 between the covers 34, and the solvent is sprayed from the solvent discharge port 35 onto the taper portion 18. The nozzle opening 14 and the taper portion 18 with a solvent, and after the cleaning, the gas discharge port 36
From the taper portion 18 to a drying gas to dry it,
The coating liquid 7 whose viscosity has been changed or which has been cured can be removed by washing.

FIG. 7 is a schematic sectional view showing a coating head cleaning device 38 according to another embodiment of the present invention. In this embodiment, the pipe 24 is made of an open-cell porous material such as ceramic. In this embodiment, the solvent supplied to the inner circumference of the pipe 24 exudes to the outer peripheral surface of the pipe 24 and is supplied to the cleaning sheet 29, and the cleaning sheet 29 is impregnated with the solvent.

FIG. 8 is a schematic sectional view showing a coating head cleaning device 39 according to still another embodiment of the present invention. In this embodiment, the outer peripheral surface of the pipe 24 is covered with a material 40 (for example, a dust-free cloth) that has elasticity and allows the solvent to penetrate. In this embodiment, since the outer peripheral surface of the pipe 24 is covered with the elastic material 40, even if the pipe 24 is made of a hard material such as metal, the taper portion 18 of the coating head 2 and the pipe 24 are Collision can be prevented and the tapered portion 18 can be protected from impact.

FIG. 9 is a schematic sectional view showing a coating head cleaning device 41 according to another embodiment of the present invention. In this embodiment, the cleaning sheet 29
Is wound around the pipe 24 and the roller 42, and the taper portion 18 of the coating head 2 is brought into contact with the cleaning sheet 29 in the middle of the pipe 24 and the roller 42. Also in this embodiment, the cleaning sheet 29 stretched between the pipe 24 and the roller 42.
Since the taper portion 18 is in contact with, the collision between the taper portion 18 and the pipe 24 or the like can be avoided.

FIG. 10 is a schematic sectional view showing a coating head cleaning device 43 according to still another embodiment of the present invention, which is constructed separately from the table 4. In this embodiment, the cleaning sheet 29 wound around the rewinding roller 30 and the take-up roller 31 is fed into the roll 4
It is wound around the pipe 24 via 4, 45, 46.
The pipe 24, into which the solvent is supplied, is rotatably supported, and at the same time, the pipe 24 is movably supported in the horizontal direction, and is projected toward the lower surface of the coating head 2 by a driving means (not shown). , Or retreat. The pipe 24 is used for the coating object 3 conveyed by the table 4.
Minute distance from the surface of (the distance larger than the film thickness of the coating liquid 7)
It is arranged so as to separate. Further, it is preferable that the diameter of the pipe 24 is as small as possible.
It is preferable that the sum a of the minute distance between the coating object 4 and the coating object 3 and the diameter of the pipe 24 is smaller than the protruding length b of the tapered portion 18.

However, immediately before the start of coating, as shown in FIG.
As shown in (a), the pipe 24 is projected right below the taper portion 18 of the coating head 2, and the taper portion 18 is brought into contact with the cleaning sheet 29 to clean the tip of the taper portion 18. At this time, the cleaning sheet 2
9 may be stationary with respect to the coating head 2, but when the cleaning sheet 29 is run, the taper portion 1
It is preferable that the upper surface side in contact with 8 travels in the same direction as the moving direction of the table 4. Cleaning sheet 29
Traveling, the taper portion 18 can be cleaned while constantly supplying the fresh surface of the cleaning sheet 29. If the traveling direction of the cleaning sheet 29 is the same as the moving direction of the table 4, the taper portion 18 is tapered. Part 18
The cleaning direction of the cleaning sheet 29 and the moving direction of the coating object 3 with respect to the taper portion 18 can be made the same, and the disturbance of the coating liquid 7 when the coating liquid 7 is applied onto the coating object 3 is small. Become.

When the cleaning of the taper portion 18 is completed, FIG.
As shown in (b), the pipe 24 retracts and the coating head 2
Is further lowered, and the coating liquid 7 is applied from the coating head 2 to the coating object 3. At this time, since the diameter of the pipe 24 is smaller than the protruding length of the taper portion 18, the retracted pipe 24 is accommodated in the space beside the taper portion 18 on the lower surface of the coating head 2 and, therefore, the horizontal movement distance of the pipe 24. Can be made smaller.

In the above embodiment, the pipe 24 is rotatable in order to prevent the cleaning sheet 29 and the pipe 24 from being worn, but the pipe 24 may be fixed. In that case, it is preferable to form a fluororesin or the like on the outer peripheral surface of the pipe 24 to reduce friction. Further, when the pipe 24 is fixed, the through hole 28 does not need to be provided in the entire circumference, and may be provided only in a region in contact with the cleaning sheet 29. Further, when the pipe 24 is not rotated, the cross-sectional shape of the pipe 24 is not limited to the cylindrical shape and may be any shape.

FIG. 11 is a sectional view showing a coating head cleaning device 47 according to still another embodiment of the present invention. In this embodiment, the pipe 24 is provided in the case 23.
A cleaning sheet 29 such as a dust-free cloth is put on the upper surface of the case 23, and a space between the pipe 24 and the cleaning sheet 29 is filled with absorbent cotton 48. Then, the solvent that has passed through the through hole 28 of the pipe 24 and exits the pipe 24 is absorbed by the absorbent cotton 48, and the cleaning sheet 29 is wetted by the solvent through the absorbent cotton 48. Therefore, by fixing the coating head cleaning device 47 to the front end surface of the table 4 and bringing the tip of the coating head 2 into contact with the surface of the cleaning sheet 29, the tip of the coating head 2 can be similarly wiped. it can.

[0031]

According to the present invention, since the cleaning sheet impregnated with the solvent can wipe off the fluid adhering to the coating head cleanly, the line at the beginning of coating when the coating target is coated is smooth. It is also possible to make the film thickness uniform at the beginning of coating. Therefore, it is possible to reduce the area where the film thickness is not uniform at the coating start portion, so that it is possible to reduce the portion where the coating object is cut and discarded, and the product yield can be significantly improved.

Further, if the tip of the coating head is wiped while the cleaning sheet is relatively stationary with respect to the tip of the coating head, dust and dust are generated due to friction between the cleaning sheet and the coating head. It can be prevented and is suitable for use in clean rooms. Moreover, even if a dust-free cloth is used as the cleaning sheet, it is possible to prevent the generation of dust and dust, and it is suitable for use in a clean room.

On the other hand, if the tip of the coating head is wiped while moving the cleaning sheet with respect to the tip of the coating head, the coating head can be wiped by rubbing, and excess fluid can be removed more reliably. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a slot type fluid application device.

FIG. 2 is a partially cutaway exploded perspective view showing the coating head of the same.

3 (a) and 3 (b) are enlarged cross-sectional views showing how the coating liquid drops from the coating head of the same.

FIG. 4 is a plan view for explaining the state of a coating film applied on a glass substrate by the same application head.

FIG. 5 is a sectional view showing a coating head cleaning device according to an embodiment of the present invention.

FIG. 6 is a partially cutaway plan view of the coating head cleaning device of the above.

FIG. 7 is a sectional view showing a coating head cleaning device according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a coating head cleaning device according to still another embodiment of the present invention.

FIG. 9 is a sectional view showing a coating head cleaning apparatus according to still another embodiment of the present invention.

10 (a) and 10 (b) are cross-sectional views illustrating a coating head cleaning device and its operation according to still another embodiment of the present invention.

FIG. 11 is a sectional view showing a coating head cleaning apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

 2 coating head 4 table 6 slot 7 coating liquid 18 taper portion 24 pipe 28 through hole 29 cleaning sheet

Claims (6)

[Claims] 1. A method for cleaning an application head, which causes a fluid to have a constant thickness and flows out from a slot, before application of the fluid, wherein a tip of the application head is brought into contact with a cleaning sheet impregnated with a solvent. Thus, the method for cleaning the coating head is characterized in that the fluid adhering to the tip of the coating head is wiped. 2. The method of cleaning the coating head according to claim 1, wherein the cleaning sheet wipes the tip of the coating head in a state of being relatively stationary with respect to the tip of the coating head. 3. The method of cleaning an application head according to claim 1, wherein the tip of the application head is wiped while moving the cleaning sheet relative to the tip of the application head. 4. A coating head cleaning device for cleaning a coating head which makes a fluid have a constant thickness and flows out from a slot, wherein a cleaning sheet for contacting and cleaning the tip of the coating head, and the cleaning sheet. And a solvent supply means for impregnating the cleaning sheet with the solvent. 5. The coating head cleaning device according to claim 4, wherein the cleaning sheet is made of dust-free cloth. 6. A pipe that allows a solvent to pass from a hollow interior toward an outer peripheral surface of the pipe, the solvent supply means being configured, and the cleaning sheet is hung around the outer peripheral surface of the pipe to dispose the cleaning sheet. The coating head cleaning device according to claim 4 or 5, wherein the coating head cleaning device is configured to run on the outer peripheral surface of the.