JP3672377B2 - Substrate processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is also referred to as a photoresist solution, polyimide resin, SOG (Spin On Glass, silica-based film forming material) on a substrate such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display, or a substrate for an optical disk. The present invention relates to a substrate processing apparatus for applying a processing liquid such as a liquid, and more particularly to a technique for applying a processing liquid to a substrate with the processing surface of the substrate facing downward.
[0002]
[Prior art]
As a conventional substrate processing apparatus of this type, for example, a substrate holding unit that holds a substrate with the processing surface of the substrate facing downward, and a coating that discharges a photoresist liquid from a discharge unit that opens to the processing surface of the substrate Examples include a head and a processing liquid supply unit that supplies a photoresist liquid through a supply pipe connected to the coating head. In the conventional apparatus configured as described above, for example, the substrate holding unit is moved in a horizontal direction with respect to the coating head in a state where the processing surface of the substrate and the discharge unit of the coating head are brought close to each other. Thus, a photoresist solution is applied to the processing surface of the substrate.
[0003]
Note that the photoresist liquid is always supplied from the processing liquid supply unit to the coating head at a constant speed (a constant flow rate). The flow rate depends on the horizontal movement speed of the substrate holder and the desired film thickness. It is set according to.
[0004]
[Problems to be solved by the invention]
However, the conventional example having such a configuration has the following problems.
That is, within the processing surface of the same substrate, the region of the product element pattern having a complex pattern as most, and at the same time to a specific part in the processing surface to evaluate the product element There is a test element pattern region formed of a pattern (generally simpler than the product element pattern) that is different from the above-described product element pattern. When the photoresist solution is applied to such a substrate while being supplied at a constant flow rate as described above, the photoresist solution is insufficient in a region where there are many recesses that require a lot of photoresist solution. In a region where there are many flat portions where only a small amount of photoresist solution is required, there is a disadvantage that the photoresist solution is excessively supplied. In other words, the amount of photoresist solution consumed due to the different surface conditions within the processing surface of the same substrate is different, so that the photoresist solution is excessively insufficiently supplied in a certain region within the processing surface, and the like. An extreme case also occurs, and there is a problem that the photoresist solution cannot be uniformly applied within the processing surface of the same substrate.
[0005]
In addition, the state of the processing surface of each substrate is caused by, for example, a flat state that has just undergone the oxidation treatment, and various states that have irregularities after numerous mask formation processes and etching processes. Since the amount of the photoresist solution consumed at the time of application differs depending on the individual substrate, if the flow rate of the photoresist solution is set according to the moving speed of the substrate holding portion and the desired film thickness as described above, it depends on the substrate as described above. However, there is a problem that the photoresist liquid cannot be uniformly applied due to excessive or insufficient processing liquid.
[0006]
The present invention has been made in view of such circumstances, and by constantly maintaining the discharge amount of the processing liquid at a constant amount, the processing liquid can be uniformly applied regardless of the state of the processing surface of the substrate. An object of the present invention is to provide a substrate processing apparatus that can be used.
[0007]
[Means for Solving the Problems]
  In order to achieve such an object, the present invention has the following configuration.
  That is, the substrate processing apparatus according to claim 1 is a substrate holding unit that holds the substrate with the processing surface of the substrate facing downward, and a coating that discharges the processing liquid from a discharge portion that is open to the processing surface of the substrate. And a treatment liquid supply means for supplying a treatment liquid to the application means via a supply pipe connected to the application means, and a processing surface of the substrate and a discharge portion of the application means are brought close to each other. In the substrate processing apparatus for applying the processing liquid to the processing surface of the substrate by relatively moving the substrate holding means and the coating means,A capillary tube connected to the supply pipe and having an opening at a position higher than the height of the discharge portion of the application means; a liquid level sensor for detecting a liquid level of the processing liquid in the capillary tube;When relatively moving the substrate holding means and the coating means,Liquid level sensorDetected byLiquid levelAnd control means for controlling the supply of the processing liquid from the processing liquid supply means to the coating means.
[0008]
[Action]
The operation of the first aspect of the invention is as follows.
  Processing the substrate while relatively moving the substrate holding means for holding the substrate with the processing surface of the substrate facing down and the coating means supplied with the processing liquid from the processing liquid supply means via the supply pipe in close proximity Apply the treatment liquid to the surface. At this time, since the discharge unit of the coating unit and the processing surface of the substrate are in proximity to each other, the processing liquid discharged from the discharge unit of the coating unit so as to rise due to surface tension adheres to the processing surface of the substrate. For example, when many recesses are formed on the processing surface of the substrate, the discharged processing liquid decreases rapidly,Liquid level sensorRelated to the discharge volume of processing liquid detected byLiquid levelAlso decreases rapidly according to its consumption. In response to this rapid consumptionLiquid levelSince the control means controls the processing liquid supply means so as to keep the pressure constant, a large amount of processing liquid is supplied from the processing liquid supply means. On the other hand, when many flat portions are formed on the processing surface of the substrate, the discharged processing liquid exhibits a gradual decrease without rapidly decreasing,Liquid level sensorDetectLiquid levelWill gradually decrease according to the consumption. In response to this gradual decreaseLiquid levelSince the control means controls the processing liquid supply means so as to hold the pressure constant, the processing liquid supply means supplies a small amount of processing liquid. Therefore, the discharge amount of the processing liquid in the discharge portion of the coating unit can always be kept constant.
[0009]
  Also, to the application meansSince the processing liquid is supplied from the processing liquid supply means via the supply pipe, the liquid level of the processing liquid in the narrow tube having an opening at a position higher than the height of the discharge part of the coating means connected to the supply pipe. Is displaced up and down according to the discharge amount of the processing liquid discharged from the discharge portion. That is, when the discharged processing liquid is consumed rapidly, the liquid level also decreases rapidly. On the other hand, when it is slowly consumed, the liquid level also decreases gradually. Therefore, this liquid level displacementDetected by the liquid level sensorThe control means controls the supply amount of the treatment liquid via the treatment liquid supply means so as to keep the liquid surface level constant, so that the discharge amount of the treatment liquid at the discharge portion of the coating means is always kept constant. Can do. By the way, the discharge amount of the processing liquid is the amount of the processing liquid existing at the interval between the processing surface of the substrate and the discharge portion of the coating unit. However, the interval is very small and the substrate and the coating unit move relative to each other. Therefore, it is difficult to detect the discharge amount directly. Therefore, the discharge amount can be indirectly detected and controlled by detecting the liquid level related to the amount as described above.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a partially broken longitudinal sectional view and a block diagram showing a main part of a substrate processing apparatus according to an embodiment. Although a semiconductor wafer will be described as an example of a substrate to be processed, this semiconductor wafer is hereinafter simply referred to as a substrate. The processing liquid will be described taking a photoresist liquid as an example.
[0011]
In the figure, reference numeral 1 denotes a suction chuck that sucks and holds the substrate W in a horizontal posture with the processing surface facing downward. The suction chuck 1 is suspended and supported by an elevating block 5 via a support member 3 erected at the center of the upper surface. The elevating block 5 is fitted to a linear guide 9 disposed along the vertical direction on one side surface of the horizontal moving member 7 so as to be movable up and down, and a rotating shaft of an elevating motor 11 provided in parallel with the linear guide 9. The ball screw 13 is interlocked with the ball screw 13. The substrate W is moved up and down integrally with the suction chuck 1, the support member 3, and the lifting block 5 by driving the lifting motor 11, and the lowered processing height shown in FIG. 1 is raised above this processing height. It is moved up and down over the conveying height [at the time of substrate delivery]. The suction chuck 1 corresponds to the substrate holding means of the present invention.
[0012]
The horizontal moving member 7 is fitted at an upper portion thereof into a linear guide 14 disposed above the substrate transfer opening 12 in the apparatus container 10 and extending from the back side to the front side. Further, the horizontal moving member 7 is screwed to a ball screw 16 arranged along the lower side of the linear guide 14. The back side portion of the ball screw 16 is interlocked and connected to the rotating shaft of the horizontal movement motor 18. The horizontal movement member 7 is moved horizontally by driving a horizontal movement motor 18, and by this movement, a standby position near the substrate transfer opening 12 as shown by a solid line in FIG. 1 and a two-dot chain line in FIG. The substrate W is moved over a processing start position for starting the photoresist liquid coating process as shown and a processing end position for finishing the photoresist liquid coating process.
[0013]
A coating head 20 is erected on the bottom near the center of the apparatus container 10 to discharge and supply a photoresist solution to the substrate W. On the upper surface, there is formed a discharge portion 21 that opens toward the processing surface of the substrate W and discharges the supplied photoresist solution so that it rises due to surface tension. The height is set to a height H1 by a base 20a provided at the bottom of the apparatus container 10. The coating head 20 has an external shape as shown in the perspective view of FIG. That is, the discharge unit 21 formed on the upper surface has a length A corresponding to at least the diameter (substrate size) of the substrate W in a direction perpendicular to the horizontal movement direction of the substrate W (direction toward the paper surface in FIG. 1). The width B is extremely shorter than the length A. That is, the discharge part 21 is formed in a slit shape. As an example of specific dimensions of the discharge unit 21, when the size of the substrate W to be processed is 8 inches, the length A is about 200 mm and the width B is about 0.1 mm. In addition, said discharge head 20 is corresponded to the application | coating means in this invention. Further, the discharge part 21 may be formed in an elongated shape with a plurality of pores instead of the slit-shaped opening.
[0014]
As shown in FIGS. 1 and 2, the coating head 20 is formed with a supply path 22 having a letter L shape in a longitudinal section L so as to communicate with the discharge unit 21. The supply path 22 is connected to a reservoir tank 26 for temporarily storing the photoresist solution via a supply pipe 24 disposed on the side surface of the coating head 20. The photoresist liquid is supplied from the supply tank 28 to the reservoir tank 26 by a pump 30 that is controlled by a control unit described later. The pump 30 may be a diaphragm pump, but is preferably a precision pump that can finely adjust the amount of photoresist solution supplied by driving a piston with a stepping motor for the reasons described later.
[0015]
Near the reservoir tank 26 of the supply pipe 24, a narrow tube 32 opened at a height position H2 located above the height position H1 of the discharge section 21 of the coating head 20 is connected in communication. The thin tube 32 is composed of a glass tube having such a transparency that the level of the photoresist liquid staying in the tube can be visually confirmed from the surroundings, and has an inner diameter of about 1.5 mm, for example. is there. Above the outer peripheral surface of the thin tube 32, a liquid level sensor 34 for detecting the liquid level of the photoresist liquid staying inside is disposed. The liquid level sensor 34 detects a liquid level of the photoresist liquid staying in the narrow tube 32 and outputs a signal. The signal is given to the control unit 40. The position of the liquid level sensor 34 on the narrow tube 32 is set in advance according to the discharge height (h), which will be described later. The liquid level sensor 34 operates (turns on) only when the liquid level is set (referred to as a set liquid level), and does not operate (off) when the level is other than that. The control unit 40 is configured by a CPU, a memory, and the like (not shown), and comprehensively controls each unit of the lifting motor 11, the horizontal movement motor 18, and the pump 30 described later. The reservoir tank 26, the supply tank 28, and the pump 30 correspond to the processing liquid supply means in the present invention.
[0016]
The control unit 40 controls the pump 30 so that the output signal of the liquid level sensor 34 is turned on in advance, so that the photoresist liquid R rising from the discharge unit 21 of the coating head 20 due to surface tension as shown in FIG. The discharge height h (for example, 0.5 to 1.5 mm) is kept constant. Since the discharge height h has a close correlation with the discharge amount of the photoresist liquid R discharged from the discharge portion 21, the discharge amount of the photoresist liquid R is made constant by making the discharge height h constant. Is a specific discharge amount q set in advance.₀(This is the set discharge amount q₀Can be called). The set discharge amount q of this photoresist liquid R₀Is preset in consideration of the target film thickness of the applied photoresist solution, the horizontal movement speed of the substrate W, and the like. Since the liquid level in the thin tube 32 described above has a correlation with the discharge height h, the discharge height h can be determined by detecting the liquid level, and thus the discharge amount can be determined. The narrow tube 32 and the liquid level sensor 34 detect a physical quantity related to the discharge amount of the photoresist liquid R discharged from the discharge portion 21 and correspond to detection means in the present invention.
[0017]
Incidentally, as shown in FIG. 4A, when the photoresist liquid R is applied to the processing surface of the substrate W by horizontally moving the substrate W, the processing surface of the substrate W and the discharge unit 21 are naturally. Interval h is smaller than the discharge height h₀Therefore, the upper portion of the discharged photoresist solution R is pushed by the processing surface of the substrate W, and the discharge height h cannot be secured. However, when the photoresist liquid R is supplied so as to maintain the discharge height h, pressure is applied to the photoresist liquid R so that the discharge height h is reached, so as shown in FIG. The photoresist solution R discharged from the discharge unit 21 spreads in the horizontal direction and the set discharge amount q₀It becomes. Therefore, the discharge height of the photoresist solution R during the coating process is lower than the discharge height h before the process.₀(= Interval between the processing surface of the substrate W and the discharge unit 21), but since the pressure is applied as much as the discharge height h, the liquid level of the thin tube 32 corresponds to the discharge height h. The set liquid level is reached. Therefore, by controlling so that the level of the photoresist liquid R in the narrow tube 32 always becomes the set level, the discharge amount of the discharge unit 21 is always set to the set discharge amount q.₀Can be. As described above, the discharge amount of the photoresist liquid R is the amount of the photoresist liquid that exists within a narrow interval between the processing surface of the substrate W and the discharge portion 21, and the substrate W is applied to the discharge head 20. It is difficult to directly detect the discharge amount of the photoresist liquid due to the horizontal movement, but the discharge amount is indirectly detected by detecting the liquid level of the narrow tube 32 in this way. can do. Further, since it is necessary to finely adjust the discharge amount of the photoresist solution R, the above-described pump 30 is preferably a precision pump rather than a diaphragm pump.
[0018]
Next, the operation of the substrate processing apparatus configured as described above will be described with reference to the flowcharts of FIGS. 5 is a flowchart showing the process, and FIG. 6 is a flowchart showing the discharge control of the photoresist liquid.
[0019]
Step S1 (board loading)
A substrate transport mechanism (not shown) enters a substrate W to be processed from the substrate transport opening 12 with its processing surface facing downward, and passes the substrate W to the suction chuck 1. The suction chuck 1 sucks and holds the upper surface of the substrate W by suction. Then, the control unit 40 drives the elevating motor 11 to lower the substrate W, and sets the vertical interval between the processing surface, which is the lower surface, and the ejection unit 21 of the coating head 20 currently located on the back side. , Minute interval h₀(See FIG. 4A).
[0020]
Step S2 (move to processing start position)
The control unit 40 drives the horizontal movement motor 18 to horizontally move the horizontal movement member 7 to the far side, and moves to the processing start position where the far side peripheral portion of the substrate W is located above the coating head 20. This processing start position is the position of the substrate W shown by the two-dot chain line in FIG. 1 and the position of the substrate W shown in FIG.
[0021]
Step S3 (Discharge control start)
The control unit 40 controls the operation of the pump 30 based on the output signal of the liquid level sensor 34 and starts controlling the discharge amount from the discharge unit 21. Specifically, the control is performed as shown in the flowchart of FIG. That is, in step T1, it is determined whether or not the liquid level sensor 34 has been operated (turned on), that is, whether the liquid level of the narrow tube 32 has reached the set liquid level, and the pump 30 is turned on based on the determination result ( Step T2) or turn off (Step T3). In this way, by controlling the pump 30 and maintaining the liquid level of the narrow tube 32 at the set liquid level, the discharge amount of the photoresist liquid R discharged from the discharge unit 21 is set to the set discharge amount q.₀To. This discharge control is always executed until it is stopped in the subsequent step S6, and the discharge amount of the photoresist solution R is always set to the set discharge amount q.₀Adjust to.
[0022]
Step S4 (Start of substrate movement)
The control unit 40 drives the horizontal movement motor 18 to start moving the substrate W at a constant speed. The substrate W is moved at a constant speed from the processing start position indicated by a two-dot chain line in FIG. 1 (also in FIG. 4A) toward the back side. Therefore, as the substrate W moves, the photoresist liquid discharged from the discharge unit 21 adheres to the processing surface of the substrate W as shown in FIG. At this time, for example, a large amount of the photoresist liquid R is consumed in a region having a processing surface where many concave portions are formed, and the discharge amount of the photoresist liquid R discharged from the discharge portion 21 is set to the set discharge amount q.₀As shown in the flowchart of FIG. 6, the pump 30 is controlled so that the liquid level of the narrow tube 32 becomes the set liquid level as shown in the flowchart of FIG. Q₀To be constant. Accordingly, the discharge amount of the photoresist liquid R is set to the set discharge amount q regardless of the state of the processing surface of the substrate W.₀Therefore, the photoresist solution R can be uniformly applied to the processing surface of the substrate W. Although the moving speed of the substrate W is a constant speed, the discharge amount of the photoresist liquid R is always set to the set discharge amount q.₀Therefore, the same effect can be obtained even if the moving speed of the substrate W is varied.
[0023]
Step S5 (Is it moved to the processing end position?)
The processing branches depending on whether or not the substrate W has moved to the processing end position indicated by the dotted line in FIG. That is, when the substrate W has not reached the processing end position, the photoresist liquid R is applied to the entire processing surface of the substrate W by repeatedly executing step S4 and continuing the constant speed movement of the substrate W. When the substrate W reaches the processing end position, the process proceeds to step S6.
[0024]
Step S6 (Discharge control stop)
When the substrate W reaches the processing end position, the photoresist liquid R is ejected from the discharge amount q.₀Therefore, the discharge control shown in the flowchart of FIG. 6 is stopped. Specifically, the on / off control of the pump 30 is stopped.
[0025]
Step S7 (stopping substrate movement)
The controller 40 stops the uniform horizontal movement of the substrate W by stopping the driving of the horizontal movement motor 18. Thereafter, the control unit 40 drives the lifting motor 11 to raise the height of the substrate W from the current processing height (the height of the substrate W shown in FIGS. 1 and 4A) to the transport height, The horizontal movement motor 18 is driven to horizontally move the substrate W coated with the photoresist solution toward the standby position on the substrate transfer opening 12 side.
[0026]
Step S8 (board removal)
A substrate transport mechanism (not shown) enters from the substrate transport opening 12 and adsorbs the peripheral portion of the upper surface of the substrate W coated with the photoresist liquid on the processing surface, and then releases the suction operation of the suction chuck 1 to release the substrate transport mechanism. Receives the substrate W and carries it out of the apparatus container 10.
[0027]
After the series of processes described above, the coating process of the photoresist liquid on one substrate W is completed, and the substrate transport mechanism carries the new substrate W into the apparatus container 10 (step S1), and the series of processes described above. By performing the above, processing is sequentially performed on a plurality of substrates. As described above, when the photoresist liquid R is applied to the substrate W, the discharge amount of the photoresist liquid R discharged from the discharge portion 21 is set to the set discharge amount q.₀Therefore, the photoresist solution R can be uniformly applied regardless of the state of the processing surface of the substrate W.
[0028]
Next, the conventional example and the present invention will be compared with reference to the schematic diagram of FIG.
As shown in FIG. 7 (a), the diameter of the substrate W is length l, the left end is a reference point 0, the right end is a distance l, and the left end of the substrate W is directed from the left end to the right end as shown in FIG. 7 (b). Assume a substrate W whose processing surface roughness increases linearly. That is, it is assumed that the consumption amount of the photoresist solution increases linearly from the left end to the right end of the processing surface of the substrate W.
[0029]
As shown in FIG. 7C, since the photoresist solution is supplied at a constant flow rate in the conventional example, the discharged photoresist solution is consumed as the roughness of the processing surface increases. Therefore, as shown by the dotted line in the figure, the discharge amount of the photoresist liquid decreases linearly. On the other hand, in the present invention, by maintaining the liquid level at the set liquid level, the discharge amount of the photoresist liquid R is set as shown by the solid line in the figure.₀Can be constant.
[0030]
As a result, the film thickness of the photoresist liquid applied to the processing surface of the substrate W is as shown in FIG. In other words, in the conventional example, the discharge amount of the photoresist solution decreases and becomes insufficient toward the right end, so that the film thickness is also the target film thickness t as shown by the dotted line in the figure.₀In the present invention, the target film thickness t is uniformly distributed from the left end to the right end of the substrate W as indicated by the solid line in the figure.₀Can be obtained. That is, according to the present invention, the photoresist solution can be uniformly applied regardless of the state of the treated surface.
[0031]
In the above description, the uniformity of the coated photoresist solution in the processing surface of one substrate W has been described. However, even when a plurality of substrates having different processing surface states are processed, The photoresist liquid can be uniformly applied in the processing surface of the substrate, and the photoresist liquid can be uniformly applied to each substrate.
[0032]
In the above embodiment, the apparatus for applying the photoresist liquid while moving the substrate W in the horizontal direction by driving the horizontal movement motor 18 has been described. However, the application head 20 is moved in the horizontal direction with the substrate W fixed in position. You may comprise so that it may move to. In the above-described apparatus, the substrate W is moved in a horizontal posture along the linear guide 14 that is horizontally disposed. A linear guide 14 may be provided to move the substrate W in an inclined posture.
[0033]
In the above description, the narrow tube 32 and the liquid level sensor 34 are used as the detection means for detecting the physical quantity related to the discharge amount of the photoresist liquid. However, the present invention is limited to such a configuration. Instead, various modifications can be made. For example, a pressure sensor may be provided in the supply pipe 24 to keep the internal pressure constant. This also sets the discharge amount of the photoresist liquid discharged from the discharge portion 21 to the set discharge amount q.₀The effect similar to that of the above-described configuration can be obtained.
[0034]
【The invention's effect】
  As is clear from the above description, according to the first aspect of the present invention, it relates to the discharge amount of the processing liquid.Liquid levelTheLiquid level sensorDetected by the control meansLiquid levelBy controlling the supply amount of the processing liquid from the processing liquid supply unit so as to keep it constant, the discharge amount of the processing liquid in the discharge unit of the coating unit can always be kept constant. As a result, the processing liquid can be uniformly applied regardless of the state of the processing surface of the substrate.
[0035]
  In addition, treatment liquidThe discharge amount is the amount of processing liquid existing at a minute interval between the processing surface of the substrate and the discharge portion of the coating means, and the substrate and the coating means are moved relative to each other. Although it is difficult to detect the discharge amount, the small pipe connected to the supply pipeDetect the liquid levelAs a result, the discharge amount can be indirectly detected. Therefore, by controlling the supply amount of the processing liquid from the processing liquid supply means so that the control means keeps the liquid level constant, the discharge amount of the processing liquid in the discharge portion of the coating means can be reduced to the processing surface of the substrate. Regardless of the state, it can always be kept constant.
[Brief description of the drawings]
FIG. 1 is a partially broken longitudinal sectional view and a block diagram showing a main part of a substrate processing apparatus.
FIG. 2 is a perspective view showing an appearance of a coating head.
FIG. 3 is a diagram for explaining the discharge height and discharge amount of a photoresist liquid.
FIG. 4 is a diagram for explaining the discharge height and discharge amount of a photoresist liquid.
FIG. 5 is a flowchart of processing.
FIG. 6 is a flowchart of discharge control.
FIG. 7 is a schematic diagram for comparison between the present invention and a conventional example.
[Explanation of symbols]
W ... Substrate
1 ... Suction chuck (substrate holding means)
5 ... Elevating block
7… Horizontal moving member
14 ... Linear guide
16 ... Ball screw
18… Horizontal movement motor
20 ... Application head (application means)
21 ... Discharge part
24 ... Supply piping
26 ... Reservoir tank (treatment liquid supply means)
28 ... Supply tank (processing liquid supply means)
30 ... Pump (Processing liquid supply means)
32 ... capillary (detection means)
34 ... Liquid level sensor (detection means)
40: Control unit (control means)

Claims (1)

A substrate holding means for holding the substrate with the processing surface of the substrate facing downward, a coating means for discharging the processing liquid from a discharge portion opened to the processing surface of the substrate, and a supply pipe connected to the coating means A treatment liquid supply means for supplying the treatment liquid to the coating means via the substrate, and the substrate holding means and the coating means are moved relative to each other by bringing the processing surface of the substrate close to the discharge portion of the coating means. In the substrate processing apparatus for applying the processing liquid to the processing surface of the substrate by
A capillary tube connected to the supply pipe and having an opening at a position higher than the height of the discharge portion of the coating means;
A liquid level sensor for detecting a liquid level of the processing liquid in the narrow tube;
When the substrate holding unit and the coating unit are relatively moved, the supply of the processing liquid from the processing liquid supply unit to the coating unit is controlled based on the liquid level detected by the liquid level sensor. Control means;
A substrate processing apparatus comprising:

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