JP2000082646A - Method and device for applying coating solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for applying coating solution by which the prevention of nonuniform application of the coating solution can be adjusted automatically and the occurrence of nonuniform application can be prevented continuously. SOLUTION: A substrate coator which forms a coating film on a substrate W by supplying a coating solution from a nozzle 5 is provided with an on-off valve 8 the closing speed of which can adjusted at the time of stopping the supply of the coating solution from the nozzle 5 and a CCD camera 13 which takes the picture of the space between the nozzle 5 and substrate W. The coator is also provided with an application stopping position detecting section 20 which detects the application stopping position of the coating solution based on the picture taken with the camera 13 when the supply of the solution from the nozzle 5 is stopped by means of the valve 8 and a control section 12 which adjusts the closing speed of the valve 8 so that the detected application stopping position may become a prescribed position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a photoresist liquid or the like to a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a substrate for an optical disk (hereinafter simply referred to as a substrate). The present invention relates to a method and an apparatus for supplying a coating liquid for supplying a coating liquid to form a coating film.

[0002]

2. Description of the Related Art In order to form a photoresist film on a substrate, for example, the substrate is rotated at a low speed in a horizontal posture by a rotation support portion of a substrate coating apparatus, an air valve is opened, and the supply of a photoresist liquid from a nozzle is started. I do. Then, after the supplied photoresist solution covers the entire surface of the substrate, the air valve is closed to stop the supply of the photoresist solution from the nozzle, and by switching to high-speed rotation, excess photoresist solution is shaken off and the solvent is removed. Is volatilized to form a photoresist film having a constant thickness on the surface of the substrate.

[0003] In recent semiconductor manufacturing techniques, the photoresist film has become thinner as the line width has become finer, that is, the viscosity of the photoresist solution has been reduced. It is easier. Typical examples of the coating unevenness include a circular unevenness (called a "lake") and a non-uniform linear unevenness (called a "striation") radially generated toward the periphery of a substrate. It is. If these coating irregularities occur, the film thickness becomes non-uniform and adversely affects subsequent processes. Therefore, when the coating irregularities occur, the photoresist film is once removed, and the photoresist is adjusted again after adjusting the apparatus. A coating is formed.

[0004]

However, the prior art having such a structure has the following problems. That is, in order to perform the above adjustment, first, the process is temporarily interrupted, the needle of the air valve is operated to appropriately adjust the closing speed of the valve, and then the coating is performed on the dummy substrate.
The dummy substrate is inspected for uneven coating, and these adjustments, coating, and
Inspections need to be repeated. Therefore, there is a problem that adjustment for preventing coating unevenness is extremely complicated and requires a long time.

Since the needle of the air valve does not loosen spontaneously, the closing speed of the adjusted air valve itself is substantially invariable. However, a filter is generally attached to the piping for supplying the photoresist liquid to the nozzle. As a result, the discharge rate (discharge flow rate per time, etc.) fluctuates due to clogging of the filter, whereby the relative closing speed of the air valve with respect to the photoresist liquid changes over time (increases). In addition, the relative closing speed of the air valve with respect to the photoresist liquid also fluctuates due to a temporal change of a pump that sends the photoresist liquid to the nozzle, and it is necessary to perform the above-described adjustment for preventing the coating unevenness.

In addition, since the occurrence of coating unevenness cannot be determined without visually inspecting the coated substrate, if a plurality of substrates are sequentially processed, once the coating unevenness occurs, a plurality of coated substrates are continuously generated. There is also a problem that uneven coating occurs on the substrate.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an adjustment for preventing coating unevenness is performed by automatically adjusting a position at which a coating liquid runs out at a predetermined position. An object of the present invention is to provide a method and an apparatus for applying a coating liquid, which can be performed automatically and can prevent the occurrence of coating unevenness continuously.

[0008]

The present invention has the following configuration in order to achieve the above object. That is, a method invention according to claim 1 is a coating liquid supply method for supplying a coating liquid to a substrate to form a coating film, wherein the supply of the coating liquid from a nozzle is stopped by an on-off valve. Detecting a position where the application liquid is interrupted between the discharge port of the nozzle and the surface of the substrate as a liquid-out position, and adjusting a closing speed of the on-off valve so as to maintain the liquid-out position at a predetermined position. It is characterized by having done.

According to a second aspect of the present invention, in the method for applying a coating liquid according to the first aspect, when the liquid exhaustion position is above a predetermined position, the closing speed of the on-off valve is reduced. When the out-of-liquid position is lower than a predetermined position, the closing speed of the on-off valve is increased.

According to a third aspect of the present invention, in a substrate coating apparatus for forming a coating film by supplying a coating liquid to a substrate from a discharge port of a nozzle, the supply of the coating liquid from the nozzle is stopped. An opening / closing valve whose closing speed is adjustable, a photographing means for photographing between the discharge port of the nozzle and the surface of the substrate, and when the supply of the coating liquid from the nozzle is stopped by the opening / closing valve, A liquid-out position detecting unit that detects a position where the coating liquid is interrupted between the discharge port of the nozzle and the surface of the substrate as a liquid-out position based on an image photographed by the photographing unit, and the liquid-out position detecting unit. Control means for adjusting the closing speed of the on-off valve so as to maintain the detected liquid-running position at a predetermined position.

According to a fourth aspect of the present invention, in the substrate coating apparatus according to the third aspect, the control means includes:
When the liquid out position is above a predetermined position, the closing speed of the on-off valve is reduced, and when the liquid out position is below the predetermined position, the closing speed of the on-off valve is increased. It is characterized by having made it.

[0012]

What is the mechanism by which the inventor of the present invention generates "Rake" which is a circular coating unevenness and "Striation" which is an uneven linear coating unevenness radially generated toward the periphery of a substrate. An experiment was performed to see if it did. Specifically, a video camera for high-speed photography in which the shutter speed is set to 1/1000 sec, from the start of discharge of a photoresist solution as a coating solution to the discharge port of a nozzle from the stop of discharge to the formation of a film. An image was taken between the substrate and the substrate surface. Then, when application unevenness occurred, the behavior of the photoresist liquid as shown in FIG. 8 was observed between the discharge port of the nozzle and the substrate surface.

That is, from the state where the photoresist liquid R is supplied from the discharge port 5a of the nozzle 5 to the surface of the substrate W (FIG. 8A), at a certain closing speed for stopping the supply. When the air valve is closed, the photoresist liquid R
Does not stop immediately, but the discharge width gradually narrows according to the closing speed of the air valve (dotted line in FIG. 8A). Finally, the photoresist liquid R is interrupted at a certain position (FIG. 8B), and the photoresist liquid R above the liquid exhaustion position Pc is drawn back to the discharge port 5a, while the photoresist liquid R below the liquid exhaustion position is lower. The photoresist liquid R falls in the form of fine threads toward the surface of the substrate W (FIG. 8).
(C)). At this time, several drops of the droplet r are shown in the interrupted portion of the photoresist liquid R (only one droplet is shown in the figure because of the illustration)
Occurs, and falls later than the upper end portion of the fine thread-shaped photoresist liquid R (FIG. 8D). In other words, it was found that after the photoresist liquid R was completely dropped on the surface of the substrate W, a few drops r were dropped with a delay. Moreover,
When the drop time was longer than 30 msec, coating unevenness was remarkable.

The present inventors have further conducted various experiments, and have found that there is a relationship between the occurrence of coating unevenness mainly caused by the delayed falling droplets and the closing speed of the air valve. This relationship is shown in the graph of FIG. 9, which is a result of examining the occurrence of coating unevenness while changing the closing speed.

That is, in the range of the closing speeds V1 to V2, severe cavitation occurred due to extreme pressure fluctuation due to high-speed operation of the valve, and a large number of droplets fell along with bubbles, resulting in application unevenness. Closing speed V2-V3
In the range, the liquid-out position Pc entered the inside of the discharge port 5a of the nozzle 5 slightly, and application unevenness did not occur. In the range of the closing speeds V3 to V4, the liquid outflow position Pc was about halfway between the discharge port 5a of the nozzle 5 and the surface of the substrate W, and application unevenness occurred. Also, the closing speeds V4 to V
In the range of 5, the out-of-liquid position Pc is near the surface of the substrate W, all the photoresist liquid R above the out-of-liquid position Pc returns into the nozzle 5, the photoresist liquid R does not drop, and coating unevenness does not occur. Was. At a closing speed V5 or less, the closing speed was slower than the discharge operation of the pump, and application unevenness due to double coating occurred.

From the relationship between the closing speed of the air valve and the coating unevenness, it was found that a range in which coating unevenness occurs and a range in which uniform coating without coating unevenness is possible exist alternately. . Even in the range of the closing speeds V3 to V4, for example, when the position of the nozzle 5 is raised, the out-of-liquid position Pc is generated at the same position as the range of the closing speeds V4 to V5, so that application unevenness does not occur. Therefore, the occurrence of the coating unevenness is not affected by the occurrence of the liquid drop position Pc regardless of the occurrence of the droplet r described above.
It turns out that it depends. This is presumably because when the nozzle is raised, even if the closing speed of the opening / closing valve for the photoresist liquid is the same, the falling speed of the photoresist liquid is increased and the relative closing speed is reduced.

The method according to the first aspect of the present invention is based on the above-described knowledge, and detects a liquid-out position displaced in accordance with the closing speed of an on-off valve and determines this position as coating unevenness. Since the closing speed of the on-off valve is automatically adjusted so as to be maintained within the range where the occurrence of the unevenness does not occur, the adjustment for preventing the uneven coating can be automatically performed.

According to the second aspect of the present invention, when the liquid-out position occurs above a predetermined position where no coating unevenness occurs, the relative speed of the on-off valve to the coating liquid increases. As the closing speed is slowed, the out-of-liquid position can be returned to the predetermined position.If the out-of-liquid position occurs below the predetermined position, the relative speed of the on-off valve to the coating liquid decreases. Therefore, by increasing the closing speed, the out-of-liquid position can be returned to a predetermined position.

According to the third aspect of the present invention, the liquid-out position detecting means detects the liquid-out position of the coating liquid based on the image photographed by the photographing means. The detected out-of-liquid position is displaced in accordance with the closing speed of the on-off valve, the relative closing speed with respect to the coating liquid, and the like. By adjusting the closing speed of the on-off valve, adjustment for preventing uneven coating can be automatically performed.

According to the apparatus of the fourth aspect of the present invention, when the liquid shortage position is located above a predetermined position where no coating unevenness occurs, the relative speed of the on-off valve with respect to the coating liquid increases. Since the control means slows the closing speed of the on-off valve, the out-of-liquid position can be returned to the predetermined position.If the out-of-liquid position occurs below the predetermined position, the on-off valve is closed. Since the relative speed with respect to the coating liquid is reduced, the liquid-out position can be returned to a predetermined position by increasing the closing speed of the on-off valve by the control means.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of the substrate coating apparatus according to the embodiment.

The substrate W is suction-supported in a horizontal posture by a suction-type spin chuck 1 and is driven to rotate about a rotation center P by an electric motor 3 via a rotation shaft 2. Around the substrate W, a scattering prevention cup 4a for preventing scattering of a photoresist liquid, which is an example of a coating liquid, is provided.
Further, an upper lid member 4b having a plurality of openings formed therein for taking in a downflow is fixed to the frame of the apparatus and fixed to the upper opening of the scattering prevention cup 4a. Have been. When a transport mechanism (not shown) places an unprocessed substrate W on the suction-type spin chuck 1 or receives a processed substrate W, a lifting mechanism (not shown) lowers only the scattering prevention cup 4a. Then, the scattering prevention cup 4a and the upper lid member 4b are separated from each other, and the suction type spin chuck 1 is moved to the scattering prevention cup 4a.
a is projected upward from the upper opening of the a.

At the side of the scattering prevention cup 4a, a supply position (solid line in the figure) corresponding to above the rotation center P of the loaded substrate W, and a retracted position (see FIG. (Dotted line in the middle) is provided. The nozzle 5 is connected through a suckback valve 7, an on-off valve 8, a filter 9, and a pump 10 to a storage tank 11 storing a photoresist solution. The suck-back valve 7 slightly pulls back the photoresist liquid exposed from the discharge port 5a of the nozzle 5 after the on-off valve 8 is closed, to prevent drying and solidification, and to suppress so-called "drips". It works.

The opening / closing operation of the opening / closing valve 8 is controlled by the control section 12, so that the opening / closing operation is performed when a supply start command in a processing program is executed, and the opening / closing valve 8 is closed when a supply stop command is executed. Has become. The opening and closing operation of the on-off valve 8 is performed by a motor 8a.
The speed at the time of closing can be adjusted by controlling the rotation speed of the motor 8a. Specifically, the motor 8
By adjusting the rotation speed of a, the closing speed is adjusted by varying the rotation of a screw shaft (not shown) and the moving speed of a valve body (not shown) screwed to the screw shaft. When executing the supply stop command included in the processing program, the control unit 12 performs the closing operation by driving the motor 8a according to the appropriate closing speed stored in the storage unit 12a. The storage unit 12a stores the “appropriate” position in the next substrate processing according to the out-of-liquid position detected during the previous substrate processing so that the out-of-liquid position is a position where no coating unevenness occurs. Closing speed ”is stored. In addition, an experiment was performed in advance, and the closing speed when no coating unevenness occurred (for example, V2 to V shown in FIG. 9).
"Conversion information" indicating the relationship between 3) and the liquid out position (for example, the liquid out position when the liquid is closed at the closing speeds V2 to V3) is stored. Note that the control unit 12 corresponds to a control unit of the present invention.

A CCD camera 13 is provided on the left side of the upper inner peripheral surface of the upper cover member 4b, and a strobe 15 is provided on the right side thereof. The CCD camera 13 corresponding to the photographing means of the present invention includes a CCD which is a solid-state image sensor, an electronic shutter corresponding to a high speed, a lens, and the like, and its photographing visual field includes the discharge port 5a of the nozzle 5. Substrate W
It is set near the surface of. For example, as shown in FIG. 3, a wide field of view is set so that the surface of the substrate W can be photographed. In this field of view, a rectangular area is set in advance as the processing area D1 so that the photoresist liquid discharged from the discharge port 5a of the supply nozzle 5 is stopped by the supply stop command and a liquid-breaking position where the photoresist liquid is interrupted can be captured.

The strobe 15 itself is installed in a dark room so that the photoresist solution is not exposed to light.
It is intended to be used as lighting when shooting, for example,
It is configured by combining a xenon lamp and a bandpass filter that transmits a wavelength of 500 nm or more. The CCD camera 13 and the strobe 15 are connected to a liquid out position detecting unit 20.

Referring to FIG. 2, a description will be given of a liquid shortage position detecting section 20 corresponding to the liquid shortage position detecting means of the present invention.

The strobe power supply 21 supplies necessary power to the strobe 15 to continuously light it. The camera control unit 22 controls the operation of the CCD camera 13, for example, controls the shooting timing and the operation speed of the electronic shutter. The instruction to start shooting to the camera control unit 22 is issued by the control unit 12 outputting a “trigger signal” to the I / O control unit 23. Although the details will be described later, the I / O control unit 23 together with the instruction to stop the supply of the photoresist solution to the substrate is provided.
To the CCD camera 13 at that time.
, Periodic photographing is started. The speed of the electronic shutter varies depending on the viscosity of the photoresist liquid, the number of rotations of the substrate at the time of supply, the distance between the discharge port 5a and the substrate surface, and the like, but the photoresist liquid supplied from the discharge port 5a runs out. The higher the speed is, the better it is for capturing the position clearly, for example, about 1/1000 sec.

An image signal in the field of view of the CCD camera 13 is transmitted to an image processing unit 24 via a camera control unit 22 and an I / O control unit 23, and a processing area D1 of the image signal (see FIG. 3). ) Are binarized and stored in the image memory 25 as still image data. The image processing unit 24 determines a liquid out position where the flow of the photoresist liquid is interrupted based on each pixel value of the still image data. Then, the control unit 1 determines whether the conversion information stored in the storage unit 12a is within the range of the liquid out position.
2 is determined, and if the value is out of the range, the closing speed is determined so as to be in the liquid-out position within the range, and this is set as “appropriate closing speed”.

Next, referring to the time chart of FIG.
The operation of the device configured as described above will be described. In this time chart, a method of supplying a photoresist liquid while rotating a substrate (a so-called dynamic method) is described as an example, but the present invention is limited to such a supply form of the photoresist liquid. Not something.

The controller 12 executes the rotation start command at time t = 0, and starts the rotation of the electric motor 3 at time t ₁ such that the rotation speed of the substrate W reaches R1 (for example, 1,500 rpm). I do. Thereafter, when the supply start command is executed at time t _S , first, the suckback valve 7 is deactivated, the motor 8 a is driven to open the on-off valve 8, and the pump 10 is further operated to operate a substantially constant flow rate. , The photoresist liquid is supplied from the storage tank 11, and the supply of the photoresist liquid from the nozzle 5 to the center of rotation of the substrate W rotating at a constant speed of R1 is started.

When the control unit 12 executes the supply stop command at the point in time t _E at which the predetermined time has elapsed, the supply of the photoresist liquid is started to be stopped in a substantially reverse order to the above-described procedure. At the same time, the control unit 12 outputs a trigger signal to the liquid shortage position detecting unit 20. When the supply stop command is issued, the storage unit 12
The on-off valve 8 is closed at the appropriate closing speed stored in a.

The out-of-liquid position detecting section 20 to which the trigger signal is applied executes the out-of-liquid position detecting process shown in the flowchart of FIG.

Step S1 (Shooting / Binary Processing) The I / O control unit 23 controls the CCD camera 13 via the camera control unit 22, and includes the discharge port 5a and the surface of the substrate W as shown in FIG. The field of view is photographed with a high-speed shutter. Then C
The image processing unit 24 processes the image signal of the visual field captured by the CD camera 13, and binarizes the processing area D1 (see FIG. 3) therein. Processing area D1 that has been binarized
Are stored in the image memory 25.

Step S2 (Drops Exist?) The image processing section 24 determines whether or not there is a liquid break position where the flow of the photoresist liquid is interrupted based on each pixel value of the still image data. The out-of-liquid position referred to here is a position where the photoresist liquid R discharged from the discharge port 5a is first divided vertically, as shown in FIG.

The still image data in the processing area D1 is divided into a plurality of pixels px, as shown in the schematic diagram of FIG. 7, and a horizontal pixel group among the plurality of pixels px is treated as one channel. ing. That is, the channels are H1, H2,... From the top. First, the pixel values of the pixels px in all the channels are checked while scanning the channels H1, H2,... In the horizontal direction. If there is no black pixel (shown by hatching in FIG. 7) indicating the photoresist liquid R in all pixels px constituting one channel, conversely, all the pixels of one channel If the value of px is a white pixel, it is determined that a liquid-out position exists.

As a result, if the liquid out position Pc exists, the process proceeds to step S3, and if not, the process returns to step S1. Even supposed to solution break position Pc is repeatedly executes steps S1~ step S2 not be detected, for example, the control unit 12 forcibly stops the process when the execution of the rotation increase command t ₂ time Therefore, the inconvenience that the photographing is repeatedly performed unnecessarily does not occur.

In this example, as shown in FIG. 7, a description will be given assuming that a liquid outflow position Pc occurs at the position of the channel H5.

Step S3 (Is the out-of-liquid position appropriate?) The controller 12 refers to the "conversion information" in the storage unit 12a and determines whether or not the channel H5 is within the range of the out-of-liquid position where application unevenness does not occur. Judge. If it is within the predetermined range, the process is terminated, and the on-off valve 8 is also opened when the next substrate is processed.
Is operated at the same appropriate closing speed (stored in the storage unit 12a) as in this processing. On the other hand, if it is out of the predetermined range, the closing speed is adjusted in order to prevent coating unevenness as described below.

Step S4 (Adjustment of Closing Speed) If the detected out-of-liquid position Pc is out of the predetermined range, the control unit 12 adjusts the current appropriate closing speed and stores the “appropriate closing speed” in the storage unit 12a. Speed ”is updated. Specifically, a new closing speed is determined based on the “conversion information” in the storage unit 12a and the channel H5 that is the current out-of-liquid position.

That is, when the channel H5, which is the current liquid-out position, is located above the range of the liquid-out position in the conversion information, the closing speed of the on-off valve 8 is high. If the channel H5 is located below the range of the liquid out position of the conversion information by the number of steps, the closing speed of the on-off valve 8 is slow, so the current appropriate closing speed is increased by a predetermined number of steps. . Then, the adjusted appropriate closing speed is stored in the storage unit 12a as a new “appropriate closing speed”.

Step S4 does not necessarily have to be performed at this time, but may be performed until the next substrate is processed. Also, instead of adjusting the appropriate closing speed by a predetermined step in the direction determined as described above, the storage unit 12
The number of steps required to prevent the coating unevenness may be determined based on the “conversion information” stored in “a”, and the adjustment may be performed in the determined direction.

Step S5 (Alarm) If it is determined in step S3 that the liquid out position is out of the predetermined range, coating unevenness has occurred when the current substrate is processed. An alarm for notifying the operator of the fact is output. Specifically, the control unit 1
2 controls the out-of-liquid position detecting unit 20 and, for example, the monitor 2
9 "The liquid out position fluctuates! Application unevenness occurs! Is output. Accordingly, the operator can know that the coating unevenness has occurred on the substrate being processed, and can prepare for the reprocessing (peeling and recoating) to be performed after the processing on all the substrates of the same processing lot is completed. it can.

The alarm may be output to the monitor 29 and the still image data of the processing area D1 stored in the image memory 25 may be displayed. As a result, an image at the time when it is determined that the liquid draining position is inappropriate is displayed, and the operator can confirm whether or not an appropriate determination has been made.

[0045] Then, as a result of the determination in step S3 described above is shown in the time chart of FIG. 4 regardless of Yes / No, the rotational speed of the electric motor 3 at t ₂ when R
After rotating the solvent to dry while removing the excess photoresist solution while maintaining the rotation speed for a certain period of time, a rotation stop command is executed at time t ₄ to complete the coating process. .

As described above, the CCD camera 13 detects the out-of-liquid position Pc displaced in accordance with the closing speed of the on-off valve 8, and adjusts the closing speed of the on-off valve 8 so as to keep this position within a range where coating unevenness does not occur. Since the control unit 12 automatically adjusts, adjustment for preventing uneven coating can be automatically performed. Therefore, even if the coating unevenness occurs on the substrate W being processed, the adjustment is automatically performed, so that the same coating unevenness can be prevented from being generated on the next substrate, and the continuous coating can be performed on a plurality of substrates W. Inconveniences such as uneven application can be prevented beforehand.

Further, since the adjustment for preventing the coating unevenness can be automatically performed without interrupting the processing, the adjustment can be completed in an extremely short time as compared with the conventional example, and the operation rate of the apparatus can be greatly reduced. Can be enhanced.

In the apparatus of the embodiment described above, a CCD camera is employed as a photographing means. However, in the present invention, various image pickup devices can be used.

[0049]

As is apparent from the above description, according to the first aspect of the present invention, a liquid-out position that is displaced in accordance with the closing speed of the on-off valve is detected, and this position is determined to cause uneven coating. Since the closing speed of the on-off valve is automatically adjusted so as to maintain the range, the adjustment for preventing the coating unevenness can be automatically performed. Therefore, even if the coating unevenness occurs, the adjustment is automatically performed, so that the problem that the coating unevenness continuously occurs on a plurality of substrates can be prevented.

According to the second aspect of the present invention, the out-of-liquid position can be returned to a predetermined position by decreasing or increasing the closing speed of the on-off valve in accordance with the detected out-of-liquid position. Thus, the adjustment for preventing the coating unevenness can be automatically performed.

According to the third aspect of the present invention, the method of the first aspect can be suitably implemented, and the adjustment for preventing the uneven coating can be automatically performed. The adjustment can be completed in an extremely short time as compared with the example, and the operation rate of the apparatus can be greatly increased.

Further, according to the device invention of the fourth aspect, the method invention of the second aspect can be suitably implemented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a substrate coating apparatus according to an embodiment.

FIG. 2 is a block diagram illustrating a schematic configuration of a liquid shortage position detection unit.

FIG. 3 is a view showing a field of view of a CCD camera.

FIG. 4 is a time chart illustrating an example of a coating process.

FIG. 5 is a flowchart illustrating a liquid-out position detecting process.

FIG. 6 is a diagram showing a state in which the photoresist liquid has run out.

FIG. 7 is a schematic diagram for explaining detection of a liquid shortage position.

FIG. 8 is a diagram provided to explain a mechanism of occurrence of coating unevenness.

FIG. 9 is a graph showing the relationship between the closing speed of an air valve and uneven coating.

[Explanation of symbols]

 W ... Substrate R ... Photoresist liquid Pc ... Liquid drain position 5 ... Nozzle 5a ... Discharge port 7 ... Suck back valve 8 ... Open / close valve 8a ... Motor 9 ... Filter 10 ... Pump 11 ... Storage tank 12 ... Control unit (control means) 12a: storage unit 13: CCD camera (photographing means) 20: liquid out position detection unit (liquid out position detection unit) 21: strobe power supply 22: camera control unit 24: image processing unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA03 AB16 EA05 4D075 AC64 AC79 CA48 DB13 DC22 EA45 4F042 AA07 BA00 BA12 CB08 EB18 5F046 JA02 JA27

Claims (4)

[Claims] 1. A coating liquid supply method for supplying a coating liquid to a substrate to form a coating film, wherein when the supply of the coating liquid from the nozzle is stopped by an on-off valve, the discharge port of the nozzle is connected to the substrate. Detecting a position where the coating liquid is interrupted between the coating liquid and the surface as a liquid-out position, and adjusting a closing speed of the on-off valve so as to maintain the liquid-out position at a predetermined position. Liquid application method. 2. The coating liquid applying method according to claim 1, wherein the closing speed of the on-off valve is reduced when the liquid out position is above a predetermined position, and the liquid out position is in a predetermined position. A method for applying a coating liquid, wherein the closing speed of the on-off valve is increased when the pressure is below the opening. 3. A substrate coating apparatus for supplying a coating liquid from a discharge port of a nozzle to a substrate to form a coating film, wherein the closing speed when stopping the supply of the coating liquid from the nozzle is adjustable. A valve, a photographing means for photographing between the discharge port of the nozzle and the surface of the substrate, and based on an image photographed by the photographing means when supply of the coating liquid from the nozzle is stopped by an on-off valve. A liquid out position detecting means for detecting, as a liquid out position, a position where the application liquid is interrupted between the discharge port of the nozzle and the surface of the substrate; and a liquid out position detected by the liquid out position detecting means to a predetermined position. Control means for adjusting a closing speed of the on-off valve so as to hold the same. 4. The substrate coating apparatus according to claim 3, wherein the control unit reduces a closing speed of the on-off valve when the liquid-running position is higher than a predetermined position, and controls the liquid-running position. Wherein the closing speed of the on-off valve is increased when the position is below a predetermined position.