JP2002239445A - Coating device and coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating apparatus and a coating method, by which the film thickness near the edge part of a coating film coated by a die coat coating method can be uniformized. SOLUTION: The coating apparatus for forming a liquid film on a substrate 107 by supplying a coating liquid 105 to a coating head 101 having a parallel slit part formed by at least two blades from an apparatus for supplying liquid, which is composed of a cylinder 102, a piston 103 and a servo-motor 104 for controlling a discharge quantity and the like, to discharge the coating liquid 105, and relatively moving the coating head 101 and a substrate stage 108 is provideded with a controller 110 and a control process of a control means for controlling the acceleration of the substrate stage 108 with the change of the liquid pressure of the inside of the coating head 101 in the coating starting part, the coating finishing part and the range in the vicinity thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating apparatus and a coating method for forming a liquid film in device manufacturing or the like.

[0002]

2. Description of the Related Art In recent years, a die coating method has attracted attention as one of methods for forming a coating film in the production of liquid crystal displays, semiconductor devices, and the like. The die coating method is a method in which a coating liquid is ejected from an opening to apply the coating liquid to a part to be coated. Specifically, for example, using two die blades, a parallel slit of about 10 to 100 μm is used. This is a method in which a coating liquid is discharged from the slit portion by pressure feeding or a pump or the like using a coating head having a portion formed thereon, and directly applied to a flat substrate (glass, wafer, or the like). As a result, the effect of significantly reducing the amount of coating solution used compared to the conventionally used spin coating method,
A liquid crystal display using a rectangular substrate has an advantage that a coating film can be formed only on a necessary portion of the substrate.

[0003]

However, when a coating film is formed on a designated area by the above-mentioned die coating method,
In the vicinity of the coating start portion and the coating end portion, the coating thickness becomes large, and it is difficult to obtain a uniform film thickness over the entire coating region. Various proposals have been made for this countermeasure.
No. 339656 and JP-A-08-229482 correspond thereto. In Japanese Patent Application Laid-Open No. 06-339656, pressurized pressure feeding is adopted as the liquid supply means, and the coating film is started in anticipation of the start of the liquid feeding and a delay in the rise of the liquid pressure.
In Japanese Patent Application Laid-Open No. 08-229482, precise liquid discharge is performed by using a piston type fixed amount pump having excellent liquid sending response as a fixed amount pump as a liquid supply unit.

As described above, since the liquid discharge speed can be directly controlled by using a metering pump as the liquid supply means in the die coat coating method, the liquid discharge amount which directly affects the film thickness regardless of the physical properties such as the viscosity of the liquid can be controlled. It is considered to be advantageous because it can be managed. However, when the rise of the liquid pressure in the coating head in the coating film was measured using a piston type metering pump, which is said to have excellent liquid sending response, it was found that the discharge speed of the piston type metering pump was constant. Fluid pressure was not stable. The cause is that air bubbles remain from the piston type metering pump to valves and joints in the pipe of the application head, and when a certain amount of liquid is sent by the metering pump and the liquid pressure of the incompressible liquid rises, Is considered to be due to a change in volume due to compression due to hydraulic pressure.

In view of this, measures were taken to prevent bubbles from accumulating in the valves and joints in the pipes, and a reexamination was conducted. It took less than one second to complete. This means that the rise of the liquid pressure takes about ten times as long as the rise (acceleration time) of the piston type metering pump is set to 0.1 second. This may be caused by minute bubbles in the liquid. In other words, when a metering pump that is considered to be advantageous in controllability is used, it is necessary to remove not only bubbles in the pipe but also bubbles in the liquid, and it is considered that it is actually quite difficult to achieve this. . Since the rise and fall of the liquid pressure greatly affect the film thickness in the vicinity of the coating start portion and the coating end portion, as a result, the film thickness in the vicinity of the coating start portion and the coating end portion is made uniform even by using the metering pump. It was difficult.

An object of the present invention is to improve the uniformity of a coating film thickness when applying a liquid. It is another object of the present invention to provide a coating apparatus and a coating method for making the film thickness near the end of the applied coating film uniform.

[0007]

The present inventors have conducted trial and error studies to achieve the above object, and as a result, have found that the above object can be achieved by the following means, and have completed the present invention. .

One of the inventions of the coating apparatus according to the present invention is as follows.
A coating apparatus using a coating method that includes a coating head that discharges a coating liquid onto a substrate and that relatively moves the coating head and the substrate to form a liquid film on the substrate. When the pressure for discharging is increased from a state lower than the predetermined pressure toward the predetermined pressure, the relative speed between the application head and the substrate is controlled to be smaller than the relative speed after the pressure reaches the predetermined pressure. A coating device, comprising:

Here, it is preferable that the predetermined pressure is a pressure that should be maintained at that value after reaching the pressure. In particular, the present invention can be suitably employed at the start of coating.

Although the specific examples of the invention are described in detail in the embodiments, a configuration in which the pressure is controlled in accordance with the relative speed can be adopted. That is, one of the inventions of a coating apparatus according to the present application includes a coating method that includes a coating head that discharges a coating liquid onto a substrate, and relatively moves the coating head and the substrate to form a liquid film on the substrate. In the coating apparatus used, when the relative speed between the coating head and the substrate is increasing from a state lower than a predetermined speed toward a predetermined speed,
A coating apparatus, comprising: a control unit that controls a pressure for discharging the coating liquid from the coating head to be lower than a pressure after the relative speed has reached the predetermined speed. Here, the predetermined speed may be a speed that should be maintained at the speed after the speed is reached.

One aspect of the invention of a coating apparatus included in the present application is provided with a coating head for discharging a coating liquid onto a substrate, and forming a liquid film on the substrate by relatively moving the coating head and the substrate. In a coating apparatus using a coating method, when the pressure for discharging the coating liquid from the coating head is lowered from a predetermined pressure toward a lower pressure, the relative speed between the coating head and the substrate is reduced by A coating apparatus characterized by having control means for controlling the relative speed when the pressure is a predetermined pressure to be lower than the relative speed. In particular, the present invention can be suitably employed at the end of coating.

Although a specific example of the present invention will be described in detail in the embodiments, a configuration in which the pressure is controlled according to the relative speed may be adopted. That is, one of the inventions of a coating apparatus according to the present application includes a coating method that includes a coating head that discharges a coating liquid onto a substrate, and relatively moves the coating head and the substrate to form a liquid film on the substrate. In the coating device used, when the relative speed between the coating head and the substrate is lowered from a predetermined speed toward a lower relative speed, the pressure for discharging the coating liquid from the coating head is changed to the relative speed. Is a coating device characterized by having control means for controlling the pressure to be lower than the pressure at the predetermined speed.

In each of the above-mentioned inventions, the control means controls the control so that the ratio between the relative speed and the pressure approaches a substantially constant value when either the relative speed or the pressure changes. It is possible to suitably adopt a configuration for performing the above. Thereby, the uniformity of the film thickness can be further improved.

In each of the inventions according to the present invention, a method of controlling the relative acceleration between the substrate and the coating head can be preferably employed as a method of controlling the relative speed between the substrate and the coating head.

In particular, the inventions according to the present invention can be suitably applied to a die coating method and a die coating apparatus.

Specifically, in each of the inventions according to the present invention, it is preferable that the coating head has a slit having two parallel opposite sides. The slit is suitably constituted by two blades.

Further, in each of the inventions according to the present invention, it is possible to suitably employ a configuration having a piston type metering pump as a device for supplying the coating liquid to the coating head. In particular, it is preferable that the piston type metering pump is a syringe type pump that controls at least one of the position, the moving speed and the moving acceleration of the piston of the piston type metering pump with a servomotor or a pulse motor.

Further, in each of the inventions according to the present invention, it is preferable that the coating apparatus has a sensor for measuring the pressure. The configuration of the sensor for measuring the pressure can take various configurations, but a configuration in which a sensor for measuring the pressure of the liquid is provided in a pipe connecting the application head and a device for supplying the liquid to the application head can be preferably employed.

Further, the control means controls a servomotor for controlling the discharge amount of the liquid in the liquid supply system, and at least a discharge speed of the coating liquid discharged from the coating head,
Controlling one or more of the ejection acceleration and the ejection amount, and / or controlling a servomotor for controlling a moving means for relatively moving the substrate and the coating head, and / or a moving speed of the moving means and / or A configuration for controlling the moving acceleration can be suitably adopted.

In each of the inventions according to the present invention, a method for relatively moving the coating head and the substrate includes:
Either a method of moving the coating head or a method of moving the substrate can be adopted. In particular, a method of moving a substrate stage on which a substrate is arranged is preferable.

In each of the inventions according to the present invention, the method of controlling the relative speed or the pressure in accordance with the other includes a method of detecting the pressure or the relative speed and controlling the relative speed or the pressure in accordance with the detected value. Alternatively, a method of measuring the pressure or the relative speed in advance and controlling the relative speed or the pressure based on the control value set according to the measured value can be adopted. For example, the control means takes in the pressure of the liquid by the sensor and controls the moving speed and / or the moving acceleration of the substrate stage according to the value, and / or controls the change of the pressure of the liquid in advance. It is possible to suitably adopt a configuration that can measure and set the control value of the substrate stage according to the measured value.

One of the coating methods according to the present invention is as follows.
A coating method using a coating method for forming a liquid film on the substrate by relatively moving the coating head and the substrate, comprising a coating head for discharging a coating liquid onto the substrate, wherein the coating liquid is discharged from the coating head. When the pressure for discharging is increased from a state lower than the predetermined pressure toward the predetermined pressure, the relative speed between the application head and the substrate is controlled to be smaller than the relative speed after the pressure reaches the predetermined pressure. A coating method comprising a control step of performing the following. Here, the predetermined pressure is preferably a pressure that should be maintained at that value after reaching the pressure. In particular, the present invention can be suitably employed at the start of coating.

One of the inventions of the coating method according to the present invention, as a structure for controlling the pressure in accordance with the relative speed, includes a coating head for discharging a coating liquid onto a substrate, and the coating head and the substrate are relatively positioned. In a coating apparatus using a coating method of forming a liquid film on the substrate by moving the coating head, when the relative speed between the coating head and the substrate is increased from a state lower than a predetermined speed toward a predetermined speed, the coating is performed. A coating apparatus comprising a control unit for controlling a pressure for discharging the coating liquid from a head to be lower than a pressure after the relative speed has reached the predetermined speed. Here, the predetermined speed may be a speed that should be maintained at the speed after the speed is reached.

One aspect of the invention of a coating method included in the present application is to provide a coating head for discharging a coating liquid onto a substrate, and forming a liquid film on the substrate by relatively moving the coating head and the substrate. In a coating apparatus using a coating method, when the pressure for discharging the coating liquid from the coating head is lowered from a predetermined pressure toward a lower pressure, the relative speed between the coating head and the substrate is reduced by A coating apparatus characterized by having control means for controlling the relative speed when the pressure is a predetermined pressure to be lower than the relative speed. In particular, the present invention can be suitably employed at the end of coating.

One of the inventions of the coating method according to the present invention as a structure for controlling the pressure in accordance with the relative speed includes a coating head for discharging a coating liquid onto a substrate, and the coating head and the substrate are relatively moved. In a coating apparatus using a coating method of forming a liquid film on the substrate by moving the coating head, when the relative speed of the coating head and the substrate is lowered from a predetermined speed to a lower relative speed, the coating head And a control unit for controlling a pressure for discharging the coating liquid from a pressure lower than a pressure when the relative speed is the predetermined speed.

The coating apparatus of the present invention comprises a coating head which supplies a coating liquid from a liquid supply apparatus and discharges the coating liquid onto a substrate, and moves the coating head and the substrate stage relative to each other. In a coating apparatus using a die coat coating method for forming a liquid film on the substrate, a coating start part, a coating end part, and a range in the vicinity thereof, in accordance with a change in the liquid pressure in the coating head, the substrate stage. A configuration having control means for controlling the acceleration can be suitably adopted.

With the above-described configuration, the acceleration of the start and stop of the substrate stage is controlled in accordance with the rise and fall of the liquid pressure, particularly at the start of coating and near the end of coating. By using a servomotor or the like (a pulse motor is also possible) for moving the substrate stage or the coating head, the acceleration and speed of the movement can be controlled almost arbitrarily. However, even if an attempt is made to control the acceleration of the liquid discharge by the metering pump, the above-mentioned problem is a rate-limiting factor and there is a limit, so that the discharge liquid amount changes for less than about 1 second. This time,
Since the substrate stage moves, the film thickness in the range of the distance moved by the substrate stage becomes thin. In particular, when the moving speed of the substrate stage is high, the non-uniform film thickness region is widened. Therefore, by controlling the speed of the substrate stage, that is, the acceleration at the time of rising, in accordance with the change in the liquid pressure, a uniform film thickness can be obtained over the entire coating region. Therefore, in the coating apparatus of the present invention, a configuration having a sensor capable of monitoring the liquid pressure in the coating head can also be suitably adopted.

[0028]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a view schematically showing a coating apparatus according to a preferred embodiment of the present invention. The coating apparatus shown in FIG. 1 includes a liquid supply apparatus (liquid supply system) using a piston type metering pump, a coating head, a parallel movable substrate stage (the coating head and the substrate stage are relatively movable), and controls them. Consists of a control device.
The liquid supply system includes a cylinder 102 for holding the coating liquid 105, a piston 103, and a discharge amount control servomotor 104 for controlling the position of the piston 103 (the servomotor 104 and the piston 103 are connected by a ball screw 111 or the like).
Have been. The discharge amount can be calculated from the cross-sectional area of the cylinder 102 and the movement amount of the piston 103, and the movement acceleration, movement speed, and movement amount of the piston 103 are controlled by the control device 110, which is a control means in the present embodiment, using the servomotor 104. Thereby, the discharge speed of the coating liquid discharged from the tip of the coating head 101 which is piped from the liquid supply system,
Discharge acceleration and discharge amount can be controlled. The substrate 107 to be coated with the liquid is adsorbed on the substrate stage 108. The substrate stage 108 itself is controlled by a common control device 110 with a liquid supply system using a substrate stage control servomotor 109, and can control its moving speed and acceleration according to the discharge speed of the coating liquid. (The arrows in FIG. 1 indicate that the substrate stage 108 can be freely moved). Further, the cylinder 102 and the coating head 101
A liquid pressure sensor 106 that can monitor the liquid pressure is attached to the pipe connecting the
0 and can be reflected on the movement of the substrate stage 108. The mounting position of the liquid pressure sensor 106 is preferably near the application head 101.

Next, a description will be given of a change in the liquid pressure near the coating start portion and the coating end portion, and control of the substrate stage 108 corresponding thereto.

FIG. 2 is a graph showing a time variation of a substrate stage speed, a piston speed, and a liquid pressure in a coating apparatus and / or a coating method according to a preferred embodiment of the present invention, and a film pressure distribution in a coating direction under these conditions. FIG.
2A is a graph showing a substrate stage speed, FIG. 2B is a piston speed, FIG. 2C is a graph showing a temporal change of a liquid pressure, and FIG. 2D is a graph showing a film pressure distribution.

Therefore, the stage speed shown in FIG. 2A is changed from the piston speed distribution shown in FIG.
When the P / V is controlled by the control device or the like in FIG. 1 so that P / V becomes constant during coating in accordance with the rise and fall of the liquid pressure as shown in the liquid pressure distribution shown in FIG. As shown, it is possible to obtain a uniform film thickness distribution including the coating start portion, the coating end portion, and a range (temporal and / or coordinate range) near these portions.

The actual control value of the substrate stage may be set in advance by measuring the change in the liquid pressure and setting it in accordance with the measured value by the control device. The speed and acceleration of the substrate stage may be controlled while adjusting.

[0033]

Next, an embodiment of the present invention will be specifically described with reference to the drawings. In the coating apparatus described above, in this embodiment, the photoresist OFPR-80 is used as the coating liquid.
0 (manufactured by Tokyo Ohka Co., Ltd.) and a viscosity of 20 cps were filled in the syringe, and the piston was moved to fill the pipe and the coating head with the liquid.

Thereafter, the discharge speed is increased to 0.1 cc / sec in 0.1 second from the start of movement of the piston.
Discharge was performed at a constant speed of 1 cc / sec, and a change in liquid pressure when the speed was reduced to 0 in 0.1 second was monitored. The constant speed of the substrate stage was set to 50 mm / sec, and the acceleration of the substrate stage was set so that P / V became P (when stable) / 50 in accordance with the time change of the measured liquid pressure P. The fall time was set in the same manner. 300mm □, 1.1mm thick for substrate
(Made by Nippon Sheet Glass Co., Ltd.) was prepared and fixed to a substrate stage by suction. The slit of the coating head is 30
μm and a width of 200 mm were used.

Under the above conditions, 200 mm (coating width) × 20
A liquid film was applied to an area of 0 mm (application direction, movement amount of the substrate stage). After coating, the substrate was removed from the stage and prebaked on a hot plate to measure the film thickness in the coating direction. The result is shown in FIG. Here, FIG. 3 is a graph showing a result of a film pressure distribution in a coating direction of a coating film obtained by a coating apparatus and / or a coating method according to an embodiment of the present invention, in which the vertical axis represents the film pressure, and the horizontal axis represents the horizontal. The axis indicates the substrate position.
From FIG. 3, it can be seen that in this embodiment, a uniform film thickness can be obtained in almost the entire region of the coating including the coating start portion, the coating end portion, and the range in the vicinity thereof.

As described above, according to this embodiment,
A coating apparatus capable of obtaining a uniform film thickness over a wide area of a coating film by controlling the acceleration of the substrate stage in response to a change in liquid pressure in a coating start portion, a coating end portion, and a range in the vicinity thereof. And an application method can be provided.

[0037]

According to the present invention, the uniformity of the thickness of the coating film can be improved.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a coating apparatus according to a preferred embodiment of the present invention.

FIG. 2 shows a coating apparatus and / or a coating apparatus according to an embodiment of the present invention.
Alternatively, (A) the time change of the substrate stage speed, (B) the time change of the piston speed, (C) the time change of the liquid pressure, and (D) the film thickness distribution in the coating direction under these conditions are shown. It is a graph.

FIG. 3 is a graph showing a result of a film thickness distribution in a coating direction of a coating film obtained by a coating apparatus and / or a coating method according to one embodiment of the present invention.

[Explanation of symbols]

101: coating head, 102: cylinder, 103: piston, 104: servomotor for controlling the discharge amount, 105: coating liquid, 106: liquid pressure sensor, 107: substrate, 108:
Substrate stage, 109: servo motor for substrate stage control, 110: control device, 111: ball screw.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Fumikazu Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H025 AA00 AB16 AB17 EA04 4D075 AC02 AC93 AC94 AC95 AG21 AG26 AG27 CA48 DA06 DB70 DC21 EA05 EA19 4F041 AA05 AB01 BA02 BA34 CA02 CA16 4F042 AA07 BA04 BA07 BA25 BA27 CA01 CA09 CB02 CB03 CB11 DD19 DD25 DD34 DF11 5F046 JA02 JA03 JA27

Claims (14)

[Claims] 1. A coating apparatus comprising a coating head for discharging a coating liquid onto a substrate, wherein the coating head and the substrate are relatively moved to form a liquid film on the substrate. When increasing the pressure for discharging the coating liquid from a state lower than a predetermined pressure toward a predetermined pressure, the relative speed between the coating head and the substrate,
A coating apparatus, comprising: a control unit that controls the relative speed after the pressure reaches a predetermined pressure to be smaller than the relative speed. 2. A coating apparatus comprising a coating head for discharging a coating liquid onto a substrate, wherein the coating head and the substrate are relatively moved to form a liquid film on the substrate. And when increasing the relative speed of the substrate from a state lower than a predetermined speed toward a predetermined speed, the pressure for discharging the coating liquid from the coating head,
A coating unit having a control unit for controlling the relative speed to be lower than the pressure after the predetermined speed is reached. 3. A coating apparatus using a coating method, comprising: a coating head for discharging a coating liquid onto a substrate, wherein the coating head and the substrate are relatively moved to form a liquid film on the substrate. When the pressure for discharging the coating liquid is lowered from a predetermined pressure toward a lower pressure, the relative speed between the coating head and the substrate is higher than the relative speed when the pressure is the predetermined pressure. A coating apparatus comprising a control unit for controlling the size of the coating apparatus to be small. 4. A coating apparatus comprising a coating head for discharging a coating liquid onto a substrate, wherein the coating head and the substrate are relatively moved to form a liquid film on the substrate. When the relative speed of the substrate is lowered from a predetermined speed toward a lower relative speed, the pressure for discharging the coating liquid from the coating head is the pressure when the relative speed is the predetermined speed. An application device comprising a control unit for controlling the application device to a lower level. 5. The control means controls the ratio of the relative speed to the pressure so as to approach a substantially constant value when either the relative speed or the pressure changes. 5. The coating device according to any one of 1 to 4. 6. The coating apparatus according to claim 1, wherein the coating head has a slit having two parallel sides facing each other. 7. The coating apparatus according to claim 1, further comprising a piston type metering pump as a device for supplying the coating liquid to the coating head. 8. The piston type metering pump, wherein the piston type metering pump is a syringe type pump that controls at least one of a piston position, a moving speed and a moving acceleration of the piston type metering pump by a servo motor or a pulse motor. The coating device according to claim 7, characterized in that: 9. The coating apparatus according to claim 1, wherein the coating apparatus has a sensor for measuring the pressure. 10. The control means controls a servo motor for controlling a discharge amount of the liquid in a liquid supply system, and at least one of a discharge speed, a discharge acceleration, and a discharge amount of a coating liquid discharged from the coating head. And / or controlling a moving speed of a moving means by controlling a moving means control servomotor for relatively moving the substrate and the coating head. The coating device according to any one of claims 1 to 9, wherein: 11. A coating method using a coating method comprising: a coating head for discharging a coating liquid onto a substrate; and moving the coating head and the substrate relative to each other to form a liquid film on the substrate. When increasing the pressure for discharging the coating liquid from a state lower than a predetermined pressure toward a predetermined pressure, the relative speed between the coating head and the substrate,
A coating method comprising a control step of controlling the relative speed after the pressure reaches a predetermined pressure to be smaller than the relative speed. 12. A coating method using a coating method, comprising: a coating head for discharging a coating liquid onto a substrate; and moving the coating head and the substrate relative to each other to form a liquid film on the substrate. And when increasing the relative speed of the substrate from a state lower than a predetermined speed toward a predetermined speed, the pressure for discharging the coating liquid from the coating head,
A coating method comprising a control step of controlling the relative speed to be lower than the pressure after the predetermined speed has been reached. 13. A coating method using a coating method comprising: a coating head for discharging a coating liquid onto a substrate; and moving the coating head and the substrate relative to each other to form a liquid film on the substrate. When the pressure for discharging the coating liquid is lowered from a predetermined pressure toward a lower pressure, the relative speed between the coating head and the substrate is higher than the relative speed when the pressure is the predetermined pressure. A coating method comprising a control step of controlling the size to be reduced. 14. A coating method using a coating method comprising: a coating head for discharging a coating liquid onto a substrate; and moving the coating head and the substrate relative to each other to form a liquid film on the substrate. When the relative speed of the substrate is lowered from a predetermined speed toward a lower relative speed, the pressure for discharging the coating liquid from the coating head is the pressure when the relative speed is the predetermined speed. A coating method comprising a control step of performing control at a lower level than the above.