JP2000237664A - Ultrasonic coating head and ultrasonic coating apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an ultrasonic coating head dealable with all of substrates inclusive of a large-sized substrate by making all of coating fluids usable regardless of a drying speed and a viscosity change by changing a coating fluid to a Newton fluid by the application of ultrasonic waves. SOLUTION: In the ultrasonic coating apparatus, a predetermined gap is kept between an emitting part 103 ejecting a predetermined coating fluid in a predetermined width and a rectangular or circular substrate W having a flat coating surface and an ultrasonic applying part 104 using an ultrasonic vibrator 20 for applying ultrasonic vibration to the predetermined coating fluid in a coating state on the coating surface in order to perform uniform coating by ejecting the coating fluid through the ejecting part 103 under pressure while the ejecting part and the substrate W are relatively moved at a predetermined speed is provided in the vicinity of the ejecting part 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a coating liquid for forming a coating film on a rectangular or disk-shaped substrate having a flat surface, and more particularly to a semiconductor, liquid crystal, plasma display or the like. The present invention relates to an ultrasonic coating head for coating a non-Newtonian fluid having a thixotropic property, which is used for obtaining a uniform thin film on a flat substrate surface such as a printed circuit board, and a coating apparatus therefor.

[0002]

2. Description of the Related Art In a manufacturing process of a liquid crystal display (LCD), a semiconductor optical element, a semiconductor element, a semiconductor integrated circuit, a printed wiring board, and the like, various coating liquids such as a photoresist, an insulating material, and a solder resist are applied to an object to be coated. For example, there is a step of applying a flat surface such as a glass substrate or a semiconductor wafer to form a very thin coating film of several microns or less. Specifically, in a liquid crystal display manufacturing process, a uniform photoresist having a thickness of about 1 micron after drying is coated on the surface of a glass substrate.

[0003] In such a case, it is necessary to form a coating film having a very uniform thickness over the entire effective surface.
It is necessary to control the film thickness with high accuracy. Therefore, conventionally, a spin coater called a spin coater using a centrifugal force has been widely used as a coater. According to the spin coating method also using this spin coater, a large amount of the coating liquid is dripped onto the base layer while rotating the object to be coated at a constant rotation speed, and the coating liquid is thinly spread by centrifugal force, and the viscosity of the coating liquid is reduced. In addition, a coating film having a thickness determined by the number of rotations and the rotation time is formed on the surface of the object to be coated. In this spin coating method, the coating head is moved from the center of rotation to the outside while rotating the coating substrate at a low speed, and a fluid is sufficiently spread over the coating surface while drawing a spiral coating trajectory on the coating substrate. The coating liquid is spread and further diffused outward by the action of centrifugal force. The discharge amount of the coating liquid, which is several tens times the amount required for forming a desired coating surface, is consumed in one coating. The above is discarded as surplus liquid. Further, as the size of the substrate increases, the difference in centrifugal force between the center of rotation and the outer periphery further increases, and it becomes more and more difficult to uniform the film thickness between the center and the outside of the substrate.

[0004] On the other hand, since the resist solution of the coating solution is extremely expensive, the production cost increases if the coating solution is wasted. In addition, it is more difficult to form a uniform film with a large-sized substrate or a fluid having a low fluidity and a high viscosity, which causes a problem in quality.

As a method of solving such a drawback of the spin coating method, there has been proposed a coating apparatus called a slit coater having a coating nozzle having a slit opening in a longitudinal direction. According to this coating apparatus, the coating liquid can be supplied only from the coating head to a required area on the coating object without supplying an excessive coating liquid, so that the yield of the coating liquid can be greatly improved. In addition, since the problem of the application liquid adhering to the substrate edge and the substrate back surface generated in the centrifugal method can be solved at the same time, the production cost and productivity are improved.

[0006]

However, in the recent high-definition technology, a more severe uniform thin film is required, and there is also a demand for increasing the size of a coating symmetric substrate. In order to cope with such demands, the lead error is reduced by increasing the accuracy of a ball screw used as a relative moving means in a slit coater, the accuracy of a traveling guide rail is increased, and the speed fluctuation of a driving servo motor is increased. The supply fluid and the coating head are kept at a constant temperature in order to reduce the volume of the coating liquid and to make the supply amount of the coating liquid uniform. Finishing with high precision, and reviewing all functions compared to the past, coating is performed using a device with higher precision.

However, in order to cope with a large-sized substrate, rigidity is required in order to maintain the linearity of the slit opening of the coating head and to prevent deformation, so that the weight increases. In addition, there was a problem that high technology and careful handling and considerable time until final conditions were set were required for processing, assembly, trial operation, and actual operation, and large size and coating quality improvement were in conflict. .

On the other hand, there has been proposed a so-called slit spin coater in which a target substrate is rotated after completion of coating by a slit coater to uniformly diffuse a coating fluid by centrifugal force to form a thin film. It is desired that the coating fluid be quick-drying from the viewpoint of productivity improvement.When a thin film is formed by a slit coater, the volatile solvent of the fluid at the start of coating evaporates at the start of rotation and the fluidity decreases. As a result, the rotation makes it difficult to diffuse the application fluid.
In order to maintain and diffuse the fluidity until the start of rotation, it is necessary to apply a considerably thick film, so that the liquid efficiency is reduced by 10 to 20 times as compared with the conventional slit coating method.

Further, when the fluid-coated substrate in a thick film state is rotated, surplus liquid is scattered by centrifugal force, and adherence to the substrate edge and the back surface of the substrate is unavoidable, and the scattered surplus liquid is scattered. Since it becomes a mist and adheres to the surface on which the coating film is formed, which causes a reduction in yield, it is necessary to take measures against such a problem, and the equipment for that purpose is complicated and expensive. In addition, due to the difference in centrifugal force between the center of rotation and the outer periphery, the center is thicker, the outer periphery is thinner and it is difficult to form a uniform film over the entire effective surface. The phenomenon is remarkable, and there is a disadvantage that it is difficult to obtain a desired uniform film particularly on the outer periphery of the substrate.

[0010] The applicant of the present application has proposed that the fluid of the coating fluid be applied by applying ultrasonic vibration to a space extending in the longitudinal direction of the slit opening while communicating with the slit opening of the coating head. By controlling the discharge of the coating fluid by increasing the
Focusing on the fact that cleaning of different coating liquids can be made possible, we will continue experimental research and apply ultrasonic waves to the coating fluid temporarily stored in the coating head and the coating fluid just before or immediately after ejection. Then, we discovered the fact that the coating fluid could be brought closer to the Newtonian fluid, and by bringing it closer to the Newtonian fluid, it was possible to eliminate the rapid change in the membrane pressure even if the transport mechanism had slight vibrations as described above. It was confirmed that a uniform coating film having a gentle change gradient was formed.

Accordingly, the present invention has been made in view of the above-mentioned circumstances, and by changing the application fluid to a Newtonian fluid by applying ultrasonic waves, all the application fluids can be used regardless of the drying speed and the type of viscosity change. Provided is an ultrasonic coating head and an ultrasonic coating apparatus which can be used, can cope with all substrates including large size substrates, can secure a desired film thickness, and can improve uniformity. It is an object.

Another object of the present invention is to provide an ultrasonic coating head and an ultrasonic coating apparatus which can suppress the surplus liquid of a coating fluid extremely and can perform liquid-saving coating with high production efficiency when used together with a slit spin coater. .

[0013]

According to the present invention, in order to solve the above-mentioned problems and achieve the object, a discharge portion for discharging a predetermined application fluid at a predetermined width is provided by a rectangular or flat plate having a flat application surface. An ultrasonic coating head that performs a uniform coating by discharging at a predetermined pressure through the discharge unit while maintaining a predetermined gap between the substrate and a circular substrate and relatively moving at a predetermined speed with the substrate. An ultrasonic wave application unit of ultrasonic wave generation means for applying ultrasonic vibration to the predetermined application fluid in an application state on the application surface is provided near the discharge unit.

The ultrasonic wave generating means includes an ultrasonic wave oscillating section for making the ultrasonic wave incident substantially perpendicularly to a liquid contact portion communicating with a supply port and a discharge port of the predetermined application fluid, and an ultrasonic wave after the incident. And a reflecting shape part for directing the ultrasonic wave to the ultrasonic wave applying part by reflecting a sound wave.

Further, the ultrasonic wave oscillating section makes the ultrasonic wave incident substantially perpendicularly to the liquid contact portion along the relative movement direction, and the reflection shape section reflects the ultrasonic wave after the incident. Thus, it is characterized by comprising a curved surface portion directed to the ultrasonic wave application unit.

Further, the ultrasonic wave oscillating section causes the ultrasonic wave to be incident on the liquid contacting section substantially perpendicularly to the direction of relative movement, and the reflection shape section transmits the ultrasonic wave after the incidence. It is characterized in that it is constituted by an inclined surface portion which is reflected and directed to the ultrasonic wave application unit.

Further, the discharge section is a slit nozzle which continuously opens in the width direction.

Further, the discharge section is characterized in that a large number of fine holes are linearly arranged.

An ultrasonic coating apparatus using an ultrasonic coating head, a relative moving means for relatively moving the substrate and the ultrasonic coating head at a predetermined speed, and a discharge unit of the coating head A distance detecting means for detecting a separation distance between the tip of the coating surface and the coating surface, a coating state in which the ultrasonic coating head maintains the predetermined gap, and a lifting means for raising and lowering to a standby state in which the ultrasonic coating head is separated from the ejection unit. Supply means for supplying the application fluid at a predetermined pressure via the supply port, discharge means for discharging the application fluid via the discharge port, the relative movement means, the distance detection means, and the elevating means, A control unit is connected to the supply unit, the discharge unit, and the ultrasonic unit, and is configured to perform a predetermined control at a predetermined timing between the start of the coating and the end of the coating.

Further, the present invention is characterized in that it is used together with a substrate rotating device for removing an excess coating fluid by centrifugal force due to rotation after coating.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First, FIG. 1 is a schematic configuration diagram showing the overall configuration of an ultrasonic coating apparatus. In this figure, the ultrasonic coating apparatus is installed in a clean room of a class 100 or higher cleanness, and the moving mechanism of the substrate W to be coated is a base 10 installed on the clean room floor, and the longitudinal direction of the base 10. , A pair of guide rails 7, a holding plate 6 to which a guide bush 6 a guided by the guide rail 7 is fixed, and a substantially flat plate as shown in FIG. Suction unit 1 for sucking and holding a substrate W or a disk-shaped substrate W (not shown)
2, a ball screw 8 screwed into a ball bush (not shown) fixed to the bottom surface of the holding plate 6 to drive the holding plate 6 along the longitudinal direction of the guide rail 7, and output the ball screw 8 And a servomotor 9 fixed to the shaft or integrally formed and fixed to the base 10.

The base 10 of the holding plate 6 is placed on the base 10.
Position sensor 11 for detecting a relative movement position with respect to
Are arranged. The motor 9 and the position sensor 11 described above are connected to the control unit 100. By driving each of the motors 9 and the position sensor 11 in synchronization with each other, the substrates W sucked and held on the holding board 6 can be moved by arrows X1, X2 shown in the figure. It is configured to reciprocate in the direction.

On the other hand, a coating head moving mechanism for relatively moving the coating head 1 with respect to the substrate W to be coated includes an elevating shaft 12 (1 in FIG. 1) fixed on a base 10.
Book, but actually two are provided at the left and right positions)
A lifting / lowering servomotor 4 fixed on the lifting / lowering shaft 12, a lifting / lowering table 5 provided with a bush screwed to a ball screw (not shown) fixed to the output shaft of the servomotor 4,
An arm 3 extending from the elevator 5 on the XY plane of the drawing, a coating head 1 attached to the arm 3, and a distance attached to the arm 3 for measuring a gap between the coating head 1 and the surface of the substrate W. And two distance sensors 2 for measurement. Based on the measurement results of these distance sensors 2,
The application head 1 is moved up and down in the Z direction in the figure by appropriately driving the elevation motor 4 so as to maintain the gap with the substrate W in real time.
In FIG. 1, a supply system of the application fluid to the application head 1 and a robot mechanism for transporting the substrate W and setting it at the illustrated position are not shown.

Further, according to the description with reference to FIG. 1, the coating head 1 is moved up and down.
May be raised and lowered to maintain the gap. Instead of the configuration in which the holding plate 6 is reciprocally driven in the directions of the arrows X1 and X2 as described above, a configuration in which the holding shaft 6 side is reciprocally driven may be employed, and at least the coating head 1 and the surface of the substrate W may be moved. Any configuration is possible as long as the relative movement is possible while maintaining the gap. Further, the base 10 is not limited to the configuration in which the flat surface faces upward as shown in the figure, but may be provided standing or inclined so as to reduce the installation area.

The distance sensor 2 for distance measurement is preferably a non-contact type such as a laser sensor since there is no risk of damaging the coating surface, but is not limited to this, and may be a contact type displacement sensor. Also, two distance sensors 2 are installed in FIG. 1 so as to be able to measure portions near both edges of the substrate W, respectively. However, the installation positions of the sensors are not limited to the illustrated positions. 2 may be provided. Further, the type of the control device 100 that controls the lifting and lowering and traveling functions is not limited as long as it can perform numerical control.

The outline of the operation at the start of coating in the configuration described above is as follows. First, when a substrate W is transferred from a transfer / transfer device (not shown) to the holding plate 6, the suction portion 12 provided on the holding plate 6 The inside of a large number of suction holes is made negative by a vacuum mechanism (not shown), and when the substrate W is held in a vacuum and the substrate W is slightly warped, it is corrected to be flat along the plane of the holding plate 6. Will be retained.

Subsequently, the holding plate 6 is moved in the direction of arrow X2 in the figure so that the substrate W is positioned below the distance sensor 2 provided on the elevating arm 3 positioned at a predetermined height. , The distance to the coating symmetry plane is measured by each sensor 2,
The distance between the tip of the coating head 1 and the surface to be coated is calculated.
The number of measurement points may be one or more. When the measurement is completed, the holding plate 6 waits at a predetermined position, and preparation for the coating operation is completed.

At this time, the coating head 1 is maintained in advance in a substantially full state without bubbles, and is stored in a state where the lower end of the coating fluid is positioned slightly higher than the opening surface of the slit tip. The application fluid stored in the application head 1 has an atmospheric pressure because the slit tip of the discharge unit is open. Further, a constant pressure and an ultrasonic wave described later are always applied to the supplied application fluid at a predetermined timing. Subsequently, when the application fluid supply valve provided on the application head 1 is opened, the application fluid under pressure pushes out the application fluid stored in the application head 1 from the tip of the slit.

At this time, the head of the applied fluid to be ejected is pushed out of the head to the outside of the head, and minute hemispherical liquid balls are formed and grown at a short pitch over the entire length of the slit opening. By applying an ultrasonic wave between the surface of the substrate W and the slit surface as described later, the coating liquid becomes a Newtonian fluid, and the effect of the liquid droplet can be completely eliminated.

Incidentally, the position of the coating liquid when stored in the slit nozzle always keeps a straight line at a constant height, and the pressure and viscosity of the supplied coating fluid and the temperature including the coating head remain unchanged. If the condition is always constant and the slit width and slit wall condition are uniform, reproducibility can be ensured in the formation of liquid droplets. The state is uneven.
Therefore, when a minute liquid ball is formed over the entire length, the application head 1 is lowered so as to be in a gap until the liquid ball is crushed at the head end, so that the application fluid is applied to the application target surface and the application head end. The space between the parts can be filled without gaps.

At this time, the coating head 1 has already
It must be in a relative movement state with respect to and at a constant speed. That is, after a time t1 at which a minute liquid droplet is formed from the start of ejection, the coating head 1 and the surface to be coated are lowered so as to have a predetermined gap, and have already reached a constant speed in the running speed state. Good to control.

By performing such control, when the relative movement speed is sufficiently low, for example, 50 mm / sec, and when the descent speed is sufficiently fast, for example, 10 mm / sec, the slit width is set to 30 μm and the gap is set to about 100 μm. In this case, the application start line can be set within a variation range of ± 1 mm or less.

After the application of the predetermined range under the above conditions, the application is completed. At this time, even if the supply valve of the coating head 1 is closed, it takes time until the discharge of the coating fluid in the coating head 1 is completely stopped by the influence of the residual pressure and the intermolecular bonding force with the discharged coating fluid. For this purpose, it is preferable to reduce the moving speed in accordance with the decrease in the discharge amount. However, such control makes it difficult to secure a desired coating thickness. Therefore, the coating head 1 is provided with a suck-back function that draws the coating fluid in the coating head 1 from the slit opening at a time substantially at the same time as closing the supply valve, and discharge is stopped by adjusting the suck-back amount. ing.

Further, the operation of closing the supply valve switches to the deceleration stop mode, and the coating head 1 is raised at the same timing. That is, the timing of the four operations of closing the supply valve, opening the suck back, and decelerating and raising the coating head is set to be the same. In addition, it is sufficient that their timing is about (1 to 2 mm) beyond the desired effective application area. By performing such an operation control, it is possible to obtain a coating film forming surface in which the disposal margin (ineffective coating surface) is suppressed to within several mm from the desired effective coating surface. A certain frame application and liquid saving application can be realized.

Next, the coating head 1 will be described with reference to FIG. 2. The transmittance D of a sound wave when vertically incident on a solid plate from a fluid is represented by Bar or Rayl shown in FIG.
It can be obtained from the equation of eigh. Where ρ is the density and c is the sound velocity. From the above, when the ultrasonic wave is perpendicularly incident on the fixed plate, 1>D> 0.8, and more than 80% of the sound wave can be propagated. This vertically incident sound wave reaches almost 100 when it reaches the wall in contact with the atmosphere.
% Reflection.

Therefore, as shown in the cross-sectional view of FIG. 2B, the ultrasonic oscillator 20 is fixed on the side surface of the liquid contact portion 101 communicating with the supply port 24 and the discharge port 25, and The ultrasonic wave V generated from the sound wave oscillating unit 20 is
1 is incident substantially perpendicularly, and in the inclined shape portion 202 having a curved surface as shown in FIG.
The discharge unit 1 having a slit dimension t by reflecting at # 2
It is configured to direct the ultrasonic wave to the ultrasonic wave application unit 104 near the tip of the reference numeral 03.

In the coating head 1 having the above-described structure, when the coating head 1 is coated while being relatively moved with respect to the substrate W as shown in FIG. By applying to the application fluid which is in a state of staying between the application unit 104 and the application surface of the substrate W due to the action of the surface tension, the application fluid is changed to a Newtonian fluid. That is, since the gap between the substrate W and the discharge portion of the coating head 1 is set to be very narrow, for example, around 30 to 50 μm, liquid summaries occur on the substrate surface and the head end as shown in FIG. Will be applied. The fluid whose viscosity has been reduced by the application of ultrasonic energy to the vicinity of the liquid summaries becomes a Newtonian liquid or approaches its characteristics, so that the action of the surface tension can be smoothly spread and a uniform coating film can be formed. become. As a result, the poor flow mainly caused by the viscosity of the coating fluid and the like is greatly improved, and it is possible to satisfactorily cope with severe uniform thin film formation in high definition technology without mechanical improvement. For this reason, it is not necessary to set the traveling accuracy of the relative moving means severely as described above.

FIG. 3 is a sectional view (a) of a coating head 1 of another embodiment, and FIG. 3 (b) is a relational diagram showing a relation between a viscosity coefficient of a coating fluid and a shear stress. 3A and 3B show a state where a sound wave is applied and a case where no sound wave is applied.

First, in FIG. 3 (a), the components already described are denoted by the same reference numerals, and the description thereof will be omitted. If not described, the ultrasonic oscillation unit 20 is set so as to be substantially perpendicular to the relative movement direction of the arrow X. The ultrasonic wave is made to enter the liquid contact part 101 almost vertically. The ultrasonic wave V thus incident is further reflected downward on the inclined surface portion 102 and directed to the inside of the ultrasonic wave application portion 104 and the ejection portion 103. In this way, it is possible to simultaneously act on the application fluid in the slit nozzle portion at an inclination angle of 45 degrees at a right angle and simultaneously apply ultrasonic waves to the application fluid in the liquid-summarized state as described above. . Incidentally, it is also possible to make the incident angle slightly more than 45 degrees and to make the light obliquely incident toward the front end and to reflect more light at the front end.

Further, when an application section 104 having a size of preferably about 0.2 mm to 0.3 mm as shown in FIG. 2C is provided in a plane at the tip of the discharge section, the incident sound wave is vertically applied to the liquid sump. The energy can be propagated, and the energy irradiation efficiency can be further increased. As described above, by applying the ultrasonic wave immediately after the application, the viscosity coefficient of the applied fluid gradually decreases as the shear stress increases, as shown in FIG.

Next, FIG. 4 is a system diagram of a coating fluid supply system of the coating head 1 and shows an initial cleaning state. In the drawing, a supply port 24 at the center and left and right discharge ports 25 communicating with the liquid contact portion 101 are formed in the coating head 1, and a coating fluid is injected from the supply port 24 at a constant pressure. For this purpose, each flow path is provided with open / close valves 33, 34. The discharge port 25 is provided with a function for bleeding air from the coating head 1 when filling the inside of the coating head 1 with the coating fluid. Are connected. FIG.
At, the valves 34 of the two outlets 25 are each opened,
The state in which the cleaning liquid is injected into the coating head 1 by switching the valve 33 to generate ultrasonic waves is shown. Thereafter, after a lapse of an appropriate time, as shown in FIG.
Is closed, and the cleaning liquid K is pressure-fed so as to discharge the cleaning liquid in the direction of the arrow from the discharge portion which is the slit opening. A three-way valve 33 having a drive mechanism (not shown) is connected to the supply port 24 of the coating head 1, and is connected to a tank 35 containing a cleaning liquid via an electromagnetic valve and a pump. The three-way valve 33 is provided with a tank 36 containing a coating fluid via a pump and an electromagnetic valve.
Further, an open valve 34 communicating with a sack valve 37 is connected to each outlet 25.

After a suitable time has elapsed after that, FIG.
As shown in (b), the valve 34 on the discharge port side is opened, and at the same time, the supply valve 33 is switched from the cleaning liquid to the flow path of the coating liquid R. The ultrasound is then stopped at the appropriate time.

Thereafter, an appropriate time elapses, and FIG.
As shown in (2), the valve 34 of the discharge port is closed, and the coating liquid R is discharged from the slit opening.

Thereafter, an appropriate time elapses, and FIG.
The supply valve is switched to stop the supply of all application fluids as shown in FIG.

Thereafter, the suction valve, which is a suction device provided at the end of the discharge port 25, is operated to open the discharge valve 34 for a predetermined time and then close it.
To the state shown in. At this time, the tip of the application fluid in the application head is slightly drawn into the slit, and the application operation standby state is formed.

The discharge valve 34 and the supply valve 33 are
It goes without saying that the number of components and structures are various as long as the desired function can be achieved.

As described above, by applying ultrasonic waves to the application fluid discharged from the application head, the fluidity of the application fluid immediately before and immediately after the application can be increased, so that the flatness of the coating film is improved. It becomes possible. In addition, the ultrasonic vibration can increase the cleaning power when cleaning the inside of the head with a cleaning liquid (solvent).

The application operation will be described with reference to the operation principle diagram of FIG. 6. The state in which the application head 1 is at the position P1 is the initial state of the start of application, and will be described together with the on / off timing of the ultrasonic vibrator 20.

P1 indicates a state of the application fluid at the standby position, P2 indicates a state where a liquid ball is being formed, P3 indicates a state where the formed liquid ball is grounded to the surface to be coated,
In P4, the supply is stopped to indicate the head rising start point, and in P5, the state where the application fluid is drawn into a predetermined position by the suction action is described.

Further, it is desired that the distances A and B from the end face to be coated shown in the figure be 5 mm or less, and the non-coating area is secured about 2 mm at the end face in four directions. G in the drawing is a gap between the tip of the coating head and the coating surface of the substrate W.

In this figure, at the position P1, the coating head 1 simultaneously starts the relative movement of the substrate W, the lowering operation, and the supply valve. Thereafter, at the position P3, the relative movement speed is constant, and the minute liquid droplets
However, at this time, the coating head 1 has reached the lower limit, and the liquid droplet at the tip is grounded to the coating surface. At position P3, energization of the ultrasonic vibrator 20 is started to generate ultrasonic waves. In this state, relative movement is performed, and up to the position P4, while maintaining a constant speed, a supply pressure, and a gap G, a constant ultrasonic wave is applied to form the above Newtonian fluid to form a uniform coating surface. . Before the position P4, the suction device provided at the end of the discharge port 25 is started. When the position P4 is reached, the supply valve is closed, the discharge valve is opened, and the coating head 1 is raised,
The power supply to the ultrasonic vibrator 20 is stopped. These operations are performed simultaneously, and the relative movement stop operation is performed thereafter.

At this time, it is important that the coating fluid is sucked into the coating head 1 to a certain position. Therefore, the opening time of the discharge valve is determined by an experiment, and the discharging valve is always closed at a certain time. At the position P5, the application head is at the upper limit and the travel limit, the application fluid is at a fixed position in the head, and the application operation ends.

By operating the ultrasonic coating apparatus as described above, the fluidity of the coating fluid can be increased, and the uniformity of the coating film can be easily improved. It is needless to say that the number and arrangement of the ultrasonic transducers 20 are not limited to the example shown in the figure, and any configuration is possible as long as uniform ultrasonic waves can be applied to the liquid summary on the substrate W. is there. As described above, since the fluidity of the application fluid immediately after the discharge can be enhanced, an apparatus having a rough coating of the temperature distribution of the coating head and the surface roughness of the wall surface of the discharge part can be realized, and the condition of the coating film can be easily determined.

Further, by providing a function of measuring the gap between the coating head and the surface to be coated and a function of setting the gap before the coating operation, a change or variation in the thickness of the coating object and a change in the coating fluid can be obtained. (Flexible coating fluid). Also, a desired effective application surface can be obtained with a minimum application area.

Further, the discharge pressure of the coating fluid, the timing of the discharge of the coating fluid, the movement start timing of the coating head or the object to be coated, and the operation timing of setting the gap between the coating head and the object to be coated are appropriately controlled. By doing so, the coating start line on the coating target surface can be aligned in a straight line so as to be at a predetermined position, and a stable and uniform film thickness can be obtained with a short coating operation distance.

As described above, ultrasonic waves are not generated until the application start line is formed, and ultrasonic waves are generated immediately after the application start line is formed, so that a short moving distance (application distance) from the application start line is obtained. (2), a stable and uniform film thickness surface can be obtained, and the coating area other than the effective surface can be reduced. As a result, it is possible to obtain a coating effective formation surface as it is now with a smaller coating area and a smaller amount of coating solution than the current condition.

Further, the application device for the application fluid can be composed of a plurality of ultrasonic generators as described above, and the intensity and frequency of each ultrasonic wave can be individually controlled. It does not cause damage to the application target area or application head, and does not generate bubbles or mist particles in the discharged application fluid, and can provide an appropriate fluidity, so that it can be fine-tuned to the characteristics of the application fluid. Adjustment is possible.

Furthermore, since the fluidity of the coating fluid immediately before and immediately after the coating can be increased, it is possible to use a quick-drying coating solution, and the drying time is shortened.
Productivity is improved.

Further, by cleaning the coating head as described above, the start-up work for removing, disassembling, cleaning, assembling, attaching, and setting the conditions of the coating head is not required at all, and workability and productivity are remarkably improved. Will be improved.

Further, in determining the quality of the coating head,
In the past, there were not a few cases where what was determined to be non-defective in each process of processing and assembly was determined to be defective in the coating experiment process, but the ratio can be reduced, so the yield at the time of manufacturing the coating head can be reduced. It is possible to improve the cost and reduce the cost.

Furthermore, since a more accurate and uniform film thickness can be obtained, the yield of coating quality can be improved and the production cost can be reduced.

In addition, since the coating method is based on the premise of frame application in which the boundaries are clearly defined like a frame, the yield of the coating solution can be maintained at an extremely high level, and the excess coating solution can be applied to the end face. Does not adhere, the possibility of generating dust is low, damage to the coated surface after coating can be reduced, and it is possible to contribute to improvement in production yield.

FIG. 7 shows a coating head 1 according to another embodiment.
FIG. 2 is a perspective view of the outer appearance of the first embodiment, and the same reference numerals are given to the components already described, and the description is omitted. In the liquid contact part 101, a large number of pores 200 are formed in a straight line. The application fluid is applied onto the substrate W through these pores. At this time, liquid droplets are formed and discharged from each of the large number of pores 200 as shown in the drawing, and liquid summaries regularly distributed in the longitudinal direction with the application surface of the substrate W are formed. However, when the ultrasonic wave is applied immediately after the application, the viscosity coefficient of the application fluid gradually decreases and becomes a Newtonian fluid, so that it can be uniformly distributed with the relative movement. Pore 2
There is no problem if 00 is a uniform shape in both round holes and square holes as long as they are arranged at equal intervals. Here, if the coating quality is 1 μm ± 5%, for example, if the specification is cleared, all are good. If there is a partial rapid change in the film thickness, it is a defective product even if it is within ± 5%, and if the film thickness changes gently, it exceeds ± 5%. Is treated as good. That is, uniformity is an extremely important item for the film thickness quality. Factors that cause a sudden change in film thickness include vibration during running during running movement coating, such as ball screws and running guides (bearings).
We paid attention to vibration by servo motor system and so on. It was sufficiently considered that vibrations acted on the coating liquid during running, and the vibrations acted on the fluid as a shear force to change the viscosity of the fluid. The quality of the coating film in the ultrasonic type coating equipment largely depends on the processing accuracy of the coating head and the degree to which the running vibration during coating running can be suppressed. It was big. The formed coating film appears as a change in film thickness only in a part of the traveling route, and it is confirmed that the phenomenon has reproducibility and that the unevenness of the formed film is thin near the part thicker than the specified thickness. Have been.

As described above, when a fluid is caused to flow at a constant shear rate under isothermal conditions, when ultrasonic vibration is applied to a thixotropic fluid whose viscosity or shear stress decreases with time, shear fluid is applied to the fluid. In other words, reducing the viscosity of the fluid to a stable range is a coating method utilizing the effect of a thinning effect, and it is possible to make the coating fluid close to the properties of Newtonian fluid. It is possible to obtain a gentle film thickness distribution even for coating unevenness due to the influence of (mechanical vibration).

Further, even in the case of a paste-like high-viscosity fluid, by reducing the viscosity, bubbles remaining in the application head can be easily discharged, and a smooth discharge operation can be realized.

Since there is a possibility that the liquid staying in the flow path including the liquid contact portion 101 may gel and cause deterioration of coating quality, the inside of the coating head of the conventional ultrasonic coating apparatus is periodically replaced. Although it was necessary to disassemble and clean, the above-mentioned device applies ultrasonic vibration to the fluid in the liquid contact part and the fluid in the discharge part or the pore part, so it is possible to reduce the rate of stagnation in the flow path. In addition, the frequency of regular cleaning can be reduced, and the cleaning can be performed only by flowing the cleaning liquid through the flow path and applying ultrasonic waves without decomposition.

This is a very important factor for productivity and quality maintenance. Reproduction techniques such as assembly and condition setting after disassembly and cleaning require careful attention. Although it took time, these operations could be performed very easily and automatically without disassembly, so that even if cleaning was repeated more frequently than before to maintain fluid quality, productivity could be improved. And the coating quality and productivity can be greatly improved since the cleaning can be easily performed in a short time without lowering the coating quality.

Further, when used in combination with the slit spin coater, the surplus liquid of the application fluid is extremely suppressed, and liquid-saving application with high production efficiency can be performed.

[0070]

As described above, according to the present invention,
By changing the application fluid to a Newtonian fluid by applying ultrasonic waves, all application fluids can be used regardless of the drying speed and the type of viscosity change, and it can be applied to all substrates including large-size substrates. Ensuring the film thickness
An ultrasonic coating head and an ultrasonic coating device capable of improving uniformity can be provided.

In addition, when used in combination with the slit spin coater, the surplus liquid of the application fluid can be extremely suppressed to enable liquid-saving application with high production efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing the overall configuration of an ultrasonic coating apparatus.

2A is a formula for calculating a transmittance D, FIG. 2B is a cross-sectional view of a coating head, and FIG. 2C is an enlarged cross-sectional view of the coating head.

FIG. 3A is a cutaway view of a main part of a coating head 1 having another configuration, and FIG. 3B is a diagram showing a relationship between a shear stress and a viscosity coefficient.

FIG. 4 is a system diagram for supplying a coating fluid of a coating head.

FIGS. 5A to 5E are flow charts for explaining valve operations including coating head cleaning.

FIG. 6 is a diagram illustrating the operation of a coating head.

FIG. 7 is an external perspective view of a coating head according to another embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 coating head 2 distance sensor 3 arm 4 servo motor 5 elevating table 6 holding plate 7 guide rail 8 ball screw 9 servo motor 10 base 11 position sensor 20 ultrasonic vibrator 24 supply port 25 discharge port 27 diaphragm 101 liquid contact part 102 reflection Shape part 103 Discharge part 104 Apply part 202 Slant shape part

Claims (8)

[Claims] 1. A discharge unit for discharging a predetermined application fluid at a predetermined width, while maintaining a predetermined gap between the substrate and a rectangular or circular substrate having a flat application surface, while relatively moving at a predetermined speed with the substrate. An ultrasonic coating head that performs uniform coating by discharging at a predetermined pressure through the discharging unit, and is configured to apply ultrasonic vibration to the predetermined coating fluid in a coating state on the coating surface. An ultrasonic applying head, wherein an ultrasonic applying section of the ultrasonic generating means is provided near the discharge section. 2. The ultrasonic generator according to claim 1, further comprising: an ultrasonic generator configured to input the ultrasonic wave substantially perpendicularly to a liquid contact part communicating with a supply port and a discharge port of the predetermined application fluid. 2. The ultrasonic coating head according to claim 1, further comprising: a reflection-shaped portion configured to reflect a sound wave to direct the ultrasonic wave to the ultrasonic wave application unit. 3. 3. The ultrasonic oscillating section makes the ultrasonic wave incident substantially perpendicularly to the liquid contacting part along the relative movement direction, and the reflecting shape part reflects the ultrasonic wave after the incident. The ultrasonic coating head according to claim 2, wherein the ultrasonic coating head is configured by a curved surface portion directed to the ultrasonic application unit. 4. The ultrasonic oscillating section causes the ultrasonic wave to be incident substantially perpendicularly to the liquid contacting part so as to be substantially orthogonal to the relative movement direction, and the reflection shape section transmits the ultrasonic wave after the incident. The ultrasonic coating head according to claim 2, wherein the ultrasonic coating head is configured by an inclined shape portion that reflects the light to be directed to the ultrasonic wave application unit. 5. The ultrasonic coating head according to claim 1, wherein the discharge unit is a slit nozzle that continuously opens in a width direction. 6. The ultrasonic coating head according to claim 1, wherein the discharge section is configured by arranging a number of fine holes in a straight line. 7. An ultrasonic coating apparatus using the ultrasonic coating head according to claim 1, wherein: a relative moving unit that relatively moves the substrate and the ultrasonic coating head at a predetermined speed; Distance detecting means for detecting a separation distance between the tip of the discharge unit of the coating head and the coating surface; a coating state in which the ultrasonic coating head maintains the predetermined gap; and a standby state in which the ultrasonic coating head is separated from the discharge unit. Raising and lowering means, supplying means for supplying the application fluid at a predetermined pressure through the supply port, discharging means for discharging the coating fluid via the discharge port, the relative moving means and the distance detection Control means connected to the means, the elevating means, the supply means, the discharge means, and the ultrasonic means, and performing predetermined control at a predetermined timing between the start of coating and the end of coating. Sound wave type An ultrasonic coating device using a coating head. 8. An ultrasonic type using an ultrasonic type application head according to claim 7, wherein the ultrasonic type application head is used together with a substrate rotating device for removing an excess application fluid by centrifugal force due to rotation after application. Coating device.