Processing liquid supply method and substrate processing apparatus

Abstract

To provide a processing liquid supply method and a substrate processing apparatus that can easily adjust the liquid cut position.SOLUTION: A processing liquid supply method of a substrate processing apparatus 1 having a nozzle 8 that discharges processing liquid, a piping 12 that connects to the nozzle 8, an open / close valve 17 installed in the piping 12, and a suck-back valve 18 installed in the piping 12 between the nozzle 8 and the open / close valve 17, comprises a discharge stop process to stop the discharge of the processing liquid from the nozzle 8 by causing the open / close valve 17 to perform a closing operation, and a liquid cut position adjustment process to adjust the liquid cut position, which is a position where the processing liquid discharged in a column form from the nozzle 8 is cut, by causing the suck-back valve 18 to perform a first suction operation in conjunction with the closing of the open / close valve 17.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a processing liquid supply method and a substrate processing apparatus for processing substrates. Examples of the substrate include semiconductor substrates, FPD (Flat Panel Display) substrates, photomask glass substrates, optical disk substrates, magnetic disk substrates, ceramic substrates, and solar cell substrates. Examples of the FPD include liquid crystal display devices and organic EL (electroluminescence) display devices. [Background technology]

[0002] A conventional substrate processing apparatus includes a nozzle that discharges a processing liquid, a pipe connected to the nozzle, an on-off valve provided in the pipe, and a suck-back valve provided in the pipe between the nozzle and the on-off valve (see, for example, Patent Documents 1 and 2). The suck-back valve is used to suck the processing liquid out of the nozzle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6420604 [Patent Document 2] Japanese Patent Application Publication No. 2019-012824 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional substrate processing apparatuses have the following problem. See FIGS. 10(a) to 10(c). When the on-off valve is opened, a columnar processing liquid LQ is discharged from the nozzle 108 (see FIG. 10(a)). Thereafter, when the on-off valve is closed, the discharge of the processing liquid stops. Because the processing liquid is viscous, the position where the processing liquid runs out is below the nozzle 108. This tendency becomes more pronounced when the discharge of a processing liquid with medium to high viscosity (for example, 45 to 500 cP) is stopped, resulting in a poor liquid cut-off state. When the liquid cut-off state becomes poor, the processing liquid that has run out and drooped below the nozzle 108 is pulled back toward the nozzle 108 by the surface tension of the processing liquid, resulting in a hemispherical processing liquid protruding from the discharge port at the tip of the nozzle.

[0005] This phenomenon will be described in detail. When the on-off valve is closed, the stopping ability and reactivity of the processing liquid are poor, and the processing liquid moves a little before stopping due to inertial force. Therefore, the liquid cut-off position (height) shown in FIG. 10(b) is below the nozzle 108. When the liquid cut-off position is below the nozzle 108, the columnar processing liquid LQ at the tip of the nozzle returns to the nozzle tip surface due to surface tension after the liquid cut-off, resulting in a state in which a hemispherical processing liquid LQ protrudes from the discharge port at the tip of the nozzle 108 (see FIG. 10(c)). As a result, the liquid surface position of the processing liquid after the liquid cut-off is slightly below the tip of the nozzle 108. Note that in this specification, the "liquid cut-off position" refers to the position where the columnar processing liquid LQ discharged from the nozzle 108 is split into two when the on-off valve is closed (see FIG. 10(b)). In addition, in this specification, the "liquid surface position" refers to the processing liquid present in the flow path inside the nozzle 108 after the liquid has run out, or the downstream end position of the hemispherical processing liquid protruding from the outlet at the tip of the nozzle 108.

[0006] Typically, liquid cutoff is controlled by adjusting the speed at which the valve closes. However, with highly viscous processing liquids, it is very difficult to improve the liquid cutoff state by adjusting the valve's operating speed. Closing the valve too quickly to improve liquid cutoff can result in excessive pressure fluctuations in the processing liquid within the valve, leading to problems such as air bubbles. This can lead to various problems, such as uneven film thickness, coating irregularities, particles, and nozzle contamination, due to poor liquid cutoff. For example, when the columnar processing liquid LQ at the nozzle tip returns to the nozzle tip surface due to surface tension after cutoff, the processing liquid splashes, causing uneven film thickness and coating irregularities. Furthermore, if a hemispherical shape of the processing liquid LQ protrudes from the nozzle outlet at the tip of the nozzle 108, the solvent in the processing liquid evaporates, resulting in solidified processing liquid adhering to the tip of the nozzle 108. This can lead to particles and nozzle contamination. Furthermore, droplets from the nozzle tip may fall off during nozzle movement. If these droplets fall onto the substrate, they can cause uneven coating, film thickness abnormalities, and particle generation. Furthermore, if the droplets fall off the substrate, contamination occurs in the space where they fall.

[0007] As described above, if the processing liquid accumulates in a hemispherical shape at the tip of the nozzle 108 after the liquid runs out, various inconveniences can occur. Therefore, a suck-back valve has already been used to adjust the liquid level after the liquid runs out. Specifically, after closing the on-off valve, the suck-back valve is activated to expand the flow path within the valve, thereby sucking and pulling back the processing liquid in the flow path connected to the nozzle, and setting the liquid level within the nozzle 108. This prevents the solvent in the processing liquid from evaporating. However, as is easily understood, while conventional methods adjust the liquid level of the processing liquid, they do not adjust the position where the processing liquid runs out. Therefore, the inconvenience caused by the processing liquid running out at a position below the nozzle cannot be resolved by conventional techniques for adjusting the processing liquid level using a suck-back valve.

[0008] Patent Document 1 describes a coating device in which a "filter" is provided in the piping between the suck-back valve and the nozzle. This coating device can adjust the closing operation of the on-off valve and the start of the suction operation of the suck-back valve. This makes it easy to adjust for liquid runout (preventing the treatment liquid from dripping from the nozzle after the supply of treatment liquid from the nozzle is temporarily interrupted by the closing operation of the on-off valve). Furthermore, Patent Document 1 defines "liquid runout" as the actual cessation of the supply of treatment liquid. In other words, Patent Document 1 does not mention adjusting the "liquid runout position" as defined in the present specification.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a processing liquid supplying method and a substrate processing apparatus that enable easy adjustment of the liquid cut-off position. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention has the following configuration: That is, a processing liquid supply method according to the present invention is a processing liquid supply method for a substrate processing apparatus including a nozzle that discharges a processing liquid, a pipe connected to the nozzle, an on-off valve provided in the pipe, and a suck-back valve provided in the pipe between the nozzle and the on-off valve, the method comprising: a discharge stopping step of closing the on-off valve to stop the discharge of the processing liquid from the nozzle; and a liquid break position adjusting step of adjusting a liquid break position, which is a position where the processing liquid discharged in a columnar form from the nozzle is interrupted, by causing the suck-back valve to perform a suction operation in conjunction with the closing operation of the on-off valve. a liquid level position adjusting step of adjusting a liquid level position of the treatment liquid, which is a downstream end position of the treatment liquid present in the flow path in the nozzle, by causing the suck-back valve to perform a second suction operation after the liquid cut-off position adjusting step; Equipped with The speed of the suction operation in the liquid cut position adjusting step is faster than the speed of the second suction operation in the liquid level position adjusting step. It is characterized by the following.

[0011] According to the treatment liquid supply method of the present invention, in order to adjust the liquid cut-off position, the suck-back valve performs a suction operation in conjunction with the closing operation of the on-off valve. This makes it possible to easily adjust the liquid cut-off position, thereby easily aligning the liquid cut-off position with the tip surface of the nozzle. Furthermore, by being able to easily adjust the liquid cut-off position, it is possible to prevent the occurrence of film thickness unevenness, coating unevenness, and the like, which are caused by poor liquid cut-off conditions.

[0012] In the above-described treatment liquid supply method, the liquid break position adjusting step preferably adjusts the liquid break position to the height of the tip surface of the nozzle. Adjusting the liquid break position to the tip surface of the nozzle can, for example, reduce variations in the amount of treatment liquid discharged from the nozzle, thereby preventing film thickness unevenness caused by poor liquid break state.

[0013] Preferably, the above-described treatment liquid supply method further includes a liquid level position adjusting step of adjusting the liquid level of the treatment liquid, which is the downstream end position of the treatment liquid present in the flow path within the nozzle, by causing the suck-back valve to perform a second suction operation after the liquid cut-off position adjusting step. That is, the treatment liquid supply method performs a two-stage suction operation. The suction operation is used to adjust the liquid cut-off position, and the second suction operation is used to adjust the liquid level of the treatment liquid inside the nozzle.

[0014] In the above-described processing liquid supply method, the speed of the suction operation in the liquid cut-off position adjusting step is preferably faster than the speed of the second suction operation in the liquid level position adjusting step. By performing the suction operation in the liquid cut-off position adjusting step relatively quickly, the liquid cut-off position can be adjusted. Furthermore, by performing the second suction operation in the liquid level position adjusting step slowly, separation of droplets that may become a particle source from the sucked processing liquid can be prevented.

[0015] In the above-described treatment liquid supply method, it is preferable that the second suction operation in the liquid level position adjusting step is started after a predetermined delay time has elapsed from the end of the suction operation in the liquid run-out position adjusting step. Since there is a delay time between the suction operation and the second suction operation, it is possible to prevent the liquid run-out from becoming unstable.

[0016] In the above-described treatment liquid supply method, the liquid-running position adjusting step preferably adjusts the liquid-running position by causing the suck-back valve to start the suction operation within a predetermined period from the point in time when the closing operation of the on-off valve is completed. When a treatment liquid with a higher viscosity is used, the liquid-running position can be easily adjusted.

[0017] In the above-described treatment liquid supply method, the liquid-running position adjusting step preferably includes causing the suck-back valve to start a suction operation while the on-off valve is performing the closing operation, and then ending the suction operation after the closing operation has ended, thereby adjusting the liquid-running position. When a treatment liquid with a medium or low viscosity is used, the liquid-running position can be easily adjusted.

[0018] Further, a substrate processing apparatus according to the present invention includes: a nozzle that discharges a processing liquid; a pipe connected to the nozzle; an on-off valve provided in the pipe; a suck-back valve provided in the pipe between the nozzle and the on-off valve; and a control unit. a second suck-back valve provided in the piping between the nozzle and the on-off valve; The control unit stops the discharge of the treatment liquid from the nozzle by causing the on-off valve to perform a closing operation, and the control unit adjusts a liquid cut-off position, which is a position where the treatment liquid discharged in a columnar form from the nozzle is cut off, by causing the suck-back valve to perform a suction operation in conjunction with the closing operation of the on-off valve. After adjusting the liquid cut-off position, the suck-back valve is caused to perform a second suction operation, thereby adjusting the liquid level position of the processing liquid, which is the downstream end position of the processing liquid present in the flow path in the nozzle, and causing the suck-back valve to perform the suction operation, and also causing the second suck-back valve to perform the second suction operation. It is characterized by the following.

[0019] In the substrate processing apparatus according to the present invention, the suck-back valve performs a suction operation in conjunction with the closing operation of the on-off valve to adjust the liquid cut-off position. This makes it possible to easily adjust the liquid cut-off position, thereby easily aligning the liquid cut-off position with the tip surface of the nozzle. Furthermore, by easily adjusting the liquid cut-off position, it is possible to prevent uneven film thickness and coating caused by poor liquid cut-off.

[0020] In the substrate processing apparatus described above, it is preferable that the control unit, after adjusting the liquid cut-off position, causes the suck-back valve to perform a second suction operation to adjust the liquid level of the processing liquid, which is the downstream end position of the processing liquid present in the flow path within the nozzle. That is, the control unit performs a two-stage suction operation. The first suction operation is used to adjust the liquid cut-off position, and the second suction operation is used to adjust the liquid level of the processing liquid inside the nozzle.

[0021] Furthermore, a substrate processing apparatus according to the present invention includes a nozzle that discharges a processing liquid, a pipe connected to the nozzle, an on-off valve provided in the pipe, a suck-back valve provided in the pipe between the nozzle and the on-off valve, and a control unit, wherein the control unit stops the discharge of the processing liquid from the nozzle by causing the on-off valve to perform a closing operation, and the control unit adjusts a liquid break-off position, which is a position where the processing liquid discharged in a column form from the nozzle is interrupted, by causing the suck-back valve to perform a suction operation in conjunction with the closing operation of the on-off valve, and after adjusting the liquid break-off position, causes the suck-back valve to perform a second suction operation, thereby adjusting a liquid level position of the processing liquid, which is a downstream end position of the processing liquid present in a flow path within the nozzle, and adjusts the speed of the suction operation that adjusts the liquid break-off position to be faster than the speed of the second suction operation that adjusts the liquid level position. In the substrate processing apparatus described above, it is preferable that the suck-back valve is a single suck-back valve, and the control unit controls the single suck-back valve to perform the suction operation and the second suction operation. The liquid cut-off position can be easily adjusted using a single suck-back valve.

[0022] Preferably, the substrate processing apparatus further includes a second suck-back valve provided in the piping between the nozzle and the on-off valve, and the control unit controls the suck-back valve to perform the suction operation and the second suck-back valve to perform the second suction operation. The liquid cut-off position can be easily adjusted using two suck-back valves. [Effects of the Invention]

[0023] According to the processing liquid supply method and the substrate processing apparatus of the present invention, the liquid cut-off position can be easily adjusted. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic configuration diagram of a substrate processing apparatus according to a first embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing an on-off valve and a suck-back valve. [Figure 3] 4 is a timing chart for explaining the operation of the substrate processing apparatus according to the first embodiment. [Figure 4] 10 shows the results of an evaluation showing the relationship between the closing operation time of the on-off valve and the suction delay time of the suck-back valve. [Figure 5] 10 is an evaluation result showing the relationship between the suction delay time of the suck back valve and the suction time of the suck back valve. [Figure 6] 10 is a timing chart for explaining the operation of the substrate processing apparatus according to the second embodiment. [Figure 7] 10 is a timing chart for explaining the operation of the substrate processing apparatus according to the third embodiment. [Figure 8] 10 is a timing chart for explaining the operation of the substrate processing apparatus according to the modified example. [Figure 9] FIG. 10 is a schematic configuration diagram of a substrate processing apparatus according to a modified example. [Figure 10] (a) is a diagram showing a state in which a columnar processing liquid is being ejected from a nozzle, (b) is a diagram for explaining the position where the liquid runs out, and (c) is a diagram showing a hemispherical processing liquid adhering to the tip of the nozzle immediately after the liquid runs out. Example 1

[0025] A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a schematic diagram of a substrate processing apparatus according to the first embodiment. Fig. 2 is a vertical cross-sectional view showing an on-off valve and a suck-back valve. Fig. 3 is a timing chart for explaining the operation of the substrate processing apparatus according to the first embodiment.

[0026] (1) Configuration of the substrate processing apparatus 1 Referring to Figure 1, the substrate processing apparatus 1 includes a holding and rotating unit 2 and a processing liquid supply unit 3. The holding and rotating unit 2 holds a substrate W in a horizontal position and rotates the substrate W around a vertical axis AX1 that passes through approximately the center of the substrate W. The holding and rotating unit 2 includes a spin chuck 5 and a rotation mechanism 6. The rotation mechanism 6 includes, for example, an electric motor. The rotation mechanism 6 rotates the spin chuck 5 that holds the substrate W around the vertical axis AX1.

[0027] The spin chuck 5 is configured to hold the lower surface of the substrate W by, for example, vacuum suction. Alternatively, the spin chuck 5 may include a spin base and multiple pin members (neither of which are shown). In this case, the multiple pin members are erected on the upper surface of the spin base so as to be arranged in a ring shape around the vertical axis AX1. The multiple pin members then sandwich the side surfaces of the substrate W, thereby holding the substrate W while separating it from the upper surface of the spin base.

[0028] The processing liquid supply unit 3 includes a nozzle 8, a processing liquid supply source 10, a pipe 12, a pump 14, a filter 15, an on-off valve 17, and a suck-back valve 18.

[0029] The nozzle 8 discharges the processing liquid. The nozzle 8 includes an internal flow path 8A and a discharge port 8B. The internal flow path 8A is formed to extend in the vertical direction. The discharge port 8B is provided at the tip surface of the nozzle 8, i.e., at the lower end of the internal flow path 8A. The diameter of the discharge port 8B is, for example, 1.5 mm. However, the diameter of the discharge port 8B is not limited to 1.5 mm. The processing liquid supply source 10 stores the processing liquid. The processing liquid supply source 10 is, for example, a bottle. The processing liquid may be, for example, a photoresist liquid, an SOG (Spin on Glass Coating) liquid, an SOD (Spin on Dielectric Coating) liquid, a polyimide resin liquid, or a liquid for forming an anti-reflection film.

[0030] The distal end of the pipe 12 is connected to the proximal end of the nozzle 8. The proximal end of the pipe 12 is inserted into the processing liquid supply source 10. The pump 14 sends the processing liquid to the nozzle 8 side. The pump 14 is provided in the pipe 12 between the nozzle 8 and the processing liquid supply source 10. The filter 15 removes foreign matter and air bubbles from the processing liquid. The filter 15 is provided in the pipe 12 between the nozzle 8 and the pump 14.

[0031] The on-off valve 17 supplies and stops the supply of the processing liquid from the nozzle 8. The on-off valve 17 is provided in the piping 12 between the nozzle 8 and the filter 15. The suck-back valve 18 performs a suction operation and a push-out operation. The suck-back valve 18 is provided in the piping 12 between the nozzle 8 and the on-off valve 17. The suck-back valve 18 is disposed adjacent to the on-off valve 17, but may also be disposed away from the on-off valve 17.

[0032] The substrate processing apparatus 1 also includes a control unit 20 and a storage unit (not shown). The control unit 20 controls each component of the substrate processing apparatus 1. The control unit 20 includes one or more processors, such as a central processing unit (CPU). The storage unit includes at least one of a read-only memory (ROM), a random-access memory (RAM), and a hard disk. The storage unit stores computer programs required to control each component of the substrate processing apparatus 1.

[0033] Referring to Figure 2, the configuration of the on-off valve 17 and the suck-back valve 18 will be described. The on-off valve 17 and the suck-back valve 18 are integrated. The on-off valve 17 and the suck-back valve 18 are configured, for example, as a DCV (digital control valve) that can adjust various parameters using electrical signals.

[0034] The on-off valve 17 includes a case 21, a diaphragm 23, a rod 25, a converter 27, and an electric motor 29. The case 21 includes an upstream flow path 31, an on-off chamber 33, and a connecting flow path .

[0035] The upstream flow path 31, the open / close chamber 33, and the connecting flow path 35 are each spaces provided inside the case 21. The upstream flow path 31 is connected to a portion of the pipe 12 on the filter 15 side. The open / close chamber 33 is provided with a valve seat 37 for receiving the diaphragm 23. The connecting flow path 35 is connected to a suck-back flow path 51, which will be described later.

[0036] The diaphragm 23 is used as a valve element. The outer periphery of the diaphragm 23 is attached to the side wall of the internal space of the case 21. The diaphragm 23 separates the open / close chamber 33 from the space SP1 shown in FIG. 2. Therefore, the processing liquid in the open / close chamber 33 does not leak into the space SP1.

[0037] The center of diaphragm 23 is connected to the lower end of rod 25. The upper end of rod 25 is connected to rotation output shaft 29A of electric motor 29 via conversion unit 27. Conversion unit 27 and conversion unit 47, which will be described later, each include a plurality of gears and a guide unit. Conversion unit 27 converts the rotation of rotation output shaft 29A of electric motor 29 into linear motion in the axial direction of rod 25 (Z direction in FIG. 2). Note that stepping motors (pulse motors) are used as electric motor 29 and electric motor 49, which will be described later.

[0038] When the electric motor 29 rotates the rotary output shaft 29A in the forward direction, the rod 25 and the central portion of the diaphragm 23 descend, and then the central portion of the diaphragm 23 is pressed against the valve seat 37 (see the diaphragm 23 indicated by the dashed line in FIG. 2). This stops the flow of the treatment liquid from the open / close chamber 33 to the connecting flow path 35. In other words, the open / close valve 17 is closed.

[0039] From this state, when the electric motor 29 rotates the rotary output shaft 29A in the reverse direction, the rod 25 and the central portion of the diaphragm 23 rise. As a result, the central portion of the diaphragm 23 moves away from the valve seat 37 (see the diaphragm 23 shown by the solid line in FIG. 2). This causes the treatment liquid to flow from the open / close chamber 33 to the connecting flow path 35. In other words, the open / close valve 17 is in the open state.

[0040] The suck back valve 18 includes a case 41, a diaphragm 43, a rod 45, a conversion unit 47, and an electric motor 49. The case 41 includes a suck back flow path 51. The suck back flow path 51 is a space provided inside the case 41. The nozzle 8 side portion of the piping 12 is connected to the suck back flow path 51. The upstream flow path 31, the open / close chamber 33, the connecting flow path 35, and the suck back flow path 51 communicate with each other.

[0041] The diaphragm 43 is used as a valve element. The outer periphery of the diaphragm 43 is attached to the side wall of the internal space of the case 41. The diaphragm 43 separates the suck-back flow path 51 from the space SP2 shown in FIG. 2. The center of the diaphragm 43 is connected to the lower end of the rod 45. The upper end of the rod 45 is connected to a rotation output shaft 49A of the electric motor 49 via a conversion unit 47. The conversion unit 47 converts the rotation of the rotation output shaft 49A of the electric motor 49 into linear motion in the axial direction of the rod 45.

[0042] When the electric motor 49 rotates the rotary output shaft 49A in the forward direction, the rod 45 and the center portion of the diaphragm 43 descend (see the diaphragm 43 shown by the solid line in FIG. 2). This reduces the volume of the suck-back flow path 51. When the volume of the suck-back flow path 51 decreases, the suck-back valve 18 performs a pushing operation.

[0043] In contrast, when the electric motor 49 rotates the rotary output shaft 49A in the opposite direction, the rod 45 and the central portion of the diaphragm 43 rise (see the diaphragm 43 indicated by the dashed line in FIG. 2). This increases the volume of the suck back flow path 51. When the volume of the suck back flow path 51 increases, the suck back valve 18 performs a suction operation.

[0044] (2) Operation of the substrate processing apparatus 1 Next, the operation of the substrate processing apparatus 1 will be described with reference to Fig. 3. A transfer robot (not shown) transfers a substrate W onto the spin chuck 5 of the holding and rotating unit 2. The spin chuck 5 holds the transferred substrate W. The rotation mechanism 6 rotates the spin chuck 5, which holds the substrate W, at any timing in order to spread the processing liquid over the substrate W.

[0045] 3, the on-off valve 17 is in a closed state. That is, the center of the diaphragm 23 of the on-off valve 17 is pressed against the valve seat 37. Also, at time t0, the height of the center of the diaphragm 43 of the suck-back valve 18 is at a preset suck-back position SB2.

[0046] At time t1, the control unit 20 sends an ON signal (open signal) to the electric motor 29 of the on-off valve 17, thereby causing the on-off valve 17 to perform an opening operation. As a result, the processing liquid is discharged from the nozzle 8 onto the substrate W (processing liquid discharge step).

[0047] The opening operation of the on-off valve 17 starts at time t1 and ends at time t2. The time from time t1 to time t2 is called the opening operation time OT. In addition, in FIG. 3, the symbol AMT represents the movement amount (movement amount) of the center portion of the diaphragm 23 of the on-off valve 17. The movement amount AMT is given by the number of steps. That is, in the opening operation, the center portion of the diaphragm 23 moves the movement amount AMT in the opening operation time OT.

[0048] Furthermore, the control unit 20 starts the pushing operation of the suck back valve 18 at the end of the opening operation at time t2. The pushing operation then ends at time t3. During the pushing operation, the center of the diaphragm 43 of the suck back valve 18 moves from the suck back position SB2 to the discharge position DS. The amount of movement (amount of movement) of the center of the diaphragm 43 is also given by the number of steps.

[0049] Thereafter, at time t4, the control unit 20 sends an OFF signal (close signal) to the electric motor 29 of the on-off valve 17, thereby causing the on-off valve 17 to perform a closing operation, thereby stopping the discharge of the treatment liquid from the nozzle 8 (discharge stopping step).

[0050] The closing operation starts at time t4 and ends at time t5. The time from time t4 to time t5 is called the closing operation time CT. During the closing operation, the center of the diaphragm 23 moves the above-mentioned movement amount AMT during the closing operation time CT. The closing operation time CT is, for example, 0.1 to 0.3 seconds.

[0051] Normally, the liquid cut-off state (liquid cut-off) is adjusted by changing the closing operation time CT. However, in the case of a highly viscous processing liquid, the liquid cut-off position of the processing liquid when the on-off valve 17 is closed is lower than the height of the tip surface of the nozzle 8, making it very difficult to adjust the liquid cut-off state by changing the closing operation time CT. Therefore, the control unit 20 adjusts the liquid cut-off position by causing the suck-back valve 18 to perform a first suction operation in conjunction with the closing operation of the on-off valve 17 (liquid cut-off position adjustment process). As shown in FIG. 10(b), the liquid cut-off position is the position where the processing liquid LQ discharged in a columnar form from the nozzle 8 (nozzle 108) is cut off.

[0052] The control unit 20 adjusts the liquid break position to the height of the tip surface of the nozzle 8 (or the height of the discharge port 8B) or near that height. The liquid break position is indirectly measured at the liquid level immediately after the liquid breaks, as shown in FIG. 10(c). For example, when the height of the tip surface of the nozzle 8 is 0 mm, the liquid level immediately after the liquid breaks is adjusted to a range of -2 mm or more and 0 mm or less. Furthermore, the range of the liquid level position that indirectly indicates the liquid break position is preferably -0.5 mm or more and 0 mm or less. This makes it possible to prevent inconveniences (such as uneven film thickness and particle generation) that may occur when the liquid break position is located below the tip of the nozzle 8.

[0053] Specifically, the first suction operation of the suck-back valve 18, which is linked to the closing operation of the on-off valve 17, will be described. When adjusting the liquid cut-off position, the control unit 20 causes the suck-back valve 18 to start the first suction operation at time t5, when the closing operation of the on-off valve 17 is completed. That is, the suck-back valve 18 starts the first suction operation when a preset suction delay time DL1 has elapsed from time t4, when the closing operation of the on-off valve 17 begins, to time t5. The first suction operation is performed during a suction time SK1, from time t5 to time t6. The movement amount AM1 (number of steps) is the distance from the discharge position DS to the adjustment position SB1. During the first suction operation, the center of the diaphragm 43 of the suck-back valve 18 moves the movement amount AM1 during the suction time SK1. That is, the movement speed of the center of the diaphragm 43 is the movement amount AM1 divided by the suction time SK1.

[0054] At time t7 after adjusting the cut-off position, the control unit 20 controls the suck-back valve 18 to perform a second suction operation, thereby adjusting the liquid level of the processing liquid inside the nozzle 8 to a suck-back position SB2, which is higher than the liquid level after the liquid cut-off (liquid level adjustment process). By raising the liquid level position to an upper position inside the nozzle 8, it is possible to prevent the solvent from volatilizing from the processing liquid remaining inside the nozzle 8. The second suction operation is a suck-back operation for adjusting the liquid level. The operation amount AM2 (number of steps) of the second suction operation is the distance from the adjustment position SB1 to the suck-back position SB2. The second suction operation is performed at a speed obtained by dividing the operation amount AM2 by the suction time SK2.

[0055] Furthermore, the second suction operation is performed at a slower speed than the first suction operation. That is, the speed of the first suction operation in the liquid cut-off position adjusting process is faster than the speed of the second suction operation in the liquid level position adjusting process. The suction time SK1 of the first suction operation is, for example, 0.1 to 0.2 seconds. In contrast, the suction time SK2 of the second suction operation is, for example, 2 to 3 seconds for a high-viscosity treatment liquid. The suction time SK2 is, for example, 0.8 to 1 second for medium- and low-viscosity treatment liquids. The two operation amounts AM1 and AM2 each vary depending on the situation.

[0056] For example, if the first suction operation is performed too quickly to move the center of the diaphragm 43 from the discharge position DS to the suck-back position SB2, droplets of the processing liquid may separate from the sucked processing liquid and adhere to the inner wall of the internal flow path 8A of the nozzle 8. This is undesirable because these droplets may become a particle source when they dry. Furthermore, if the speed of the first suction operation is too slow, the process becomes a suck-back process for adjusting the liquid level position, and the function of adjusting the liquid cut-off position does not work effectively. Therefore, it is preferable to adjust the liquid cut-off position by performing the first suction operation relatively quickly in the liquid cut-off position adjustment process. Furthermore, performing the second suction operation slowly in the liquid level position adjustment process can prevent droplets that could become a particle source from separating from the sucked processing liquid.

[0057] The second suction operation begins after a second suction delay time DL2, which is the time from the end of the first suction operation t6 to a preset time t7, has elapsed. The second suction delay time DL2 is, for example, approximately 1 second (approximately 0.5 to 1.5 seconds), but is not limited to this time. The second suction delay time DL2 between the first and second suction operations prevents the liquid from running out unstably. The second suction operation begins after a suction delay time DL21, which is the sum of the first suction delay time DL1, suction time SK1, and second suction delay time DL2, based on time t4, when the close signal is sent from control unit 20.

[0058] A preset amount of processing liquid is discharged from the nozzle 8 onto the upper surface of the substrate W, and after the substrate W is rotated by the rotation mechanism 6, the rotation of the substrate W by the rotation mechanism 6 is stopped. Thereafter, the substrate W is released from the spin chuck 5. Thereafter, the transport robot holds the substrate W on the spin chuck 5 and transports the substrate W to its next destination.

[0059] Thereafter, the processing liquid is supplied from the nozzle 8 to the upper surface of another substrate W transferred onto the spin chuck 5. The operations of the on-off valve 17 and the suck-back valve 18 at times t9, t10, and t11 are the same as those of the on-off valve 17 and the suck-back valve 18 at times t1, t2, and t3.

[0060] (3) Parameters of the first suction operation In this embodiment, the control unit 20 causes the suck-back valve 18 to perform the first suction operation in conjunction with the closing operation of the on-off valve 17. This adjusts the liquid cut-off position. The parameters for adjusting the liquid cut-off position are "suction delay time DL1," "operation amount AM1," and "suction time SK1."

[0061] (3-1) Suction delay time DL1 (operation timing) In the case of a processing liquid with a relatively high viscosity (for example, 325 cP), the liquid remains fluid even after the closing operation of the on-off valve 17 is completed. Therefore, it takes time for the liquid to stop completely. By performing the first suction operation within this time, the liquid cut-off position can be adjusted.

[0062] Figure 4 shows the evaluation results showing the relationship between the closing operation time CT of the on-off valve 17 and the suction delay time DL1. Note that the operation amount AM1 and suction time SK1 are both constant values. In the evaluation of Figure 4, 325 cP silicone oil was used. A rating of A indicates that the liquid cutoff position is at or near the tip of the nozzle 8, and the function for adjusting the liquid cutoff position is working properly. A rating of B indicates a state just before a hemispherical droplet forms at the tip of the nozzle 8 immediately after the liquid cutoff. For example, a rating of B indicates a state in which a small droplet is projecting from the tip of the nozzle 8 toward the positive side. A rating of B also indicates that the function for adjusting the liquid cutoff position is working to some extent (it is usable). A rating of C indicates a state in which a hemispherical droplet is attached to the tip of the nozzle 8 immediately after the liquid cutoff, and it indicates that the function for adjusting the liquid cutoff position is not working.

[0063] For example, the evaluation results will be described for the case where the closing operation time CT shown in Figure 4 is "0.1 seconds." When the suction delay time DL1 is "0.05 seconds," the first suction operation begins too quickly, and the suction effect is not fully achieved. Therefore, the liquid break position is below the tip surface of the nozzle 8. As a result, hemispherical liquid droplets adhere to the tip surface of the nozzle 8, resulting in a C rating. When the suction delay time DL1 is "0.1 to 0.25 seconds," the evaluation is A. In this case, the liquid break position is near the tip surface of the nozzle 8, so no liquid droplets adhere to the tip surface of the nozzle 8. When the suction delay time DL1 is "0.30 seconds," the evaluation is B. When the suction delay time DL1 is "0.35 to 0.50 seconds," the timing of the first suction operation is late, and the liquid break position is below the tip surface of the nozzle 8. That is, for a moment, a hemispherical droplet adheres to the tip of the nozzle 8, and then the first suction operation is activated. Therefore, the operation is the same as normal suck back (adjustment of the liquid surface position).

[0064] 4, it can be seen that the width (period) of the range between A and B judgments is 0.2 seconds to 0.25 seconds for the three closing operation times CT. It can also be seen that the range of A judgment (the effective range of the function for adjusting the liquid-out position) shifts depending on the closing operation time CT. For example, when the closing operation time CT is 0.1 seconds, one end of the range of A judgment is the suction delay time DL1 of 0.10 seconds. Furthermore, when the closing operation time CT is 0.2 seconds, one end of the range of A judgment is the suction delay time DL1 of 0.20 seconds. Therefore, it is effective to perform the first suction operation at time t5 in FIG. 3, when the on-off valve 17 is completely closed.

[0065] (3-2) Operation amount AM1 The operating amount AM1 is the amount of processing liquid that is sucked in. If the operating amount AM1 is small, the liquid level immediately after the liquid runs out will be in a state where it protrudes from the tip face of the nozzle 8 to the positive side. If the operating amount AM1 is large, the state immediately after the liquid runs out will be a state where it is pulled in from the tip face of the nozzle 8 to the negative side. If the operating amount AM1 is too large, droplets will separate from the sucked processing liquid, and these droplets will tend to adhere to the inner wall of the internal flow path 8A of the nozzle 8. Therefore, the operating amount AM1 is set within a range that is neither too large nor too small.

[0066] (3-3) Suction time SK1 The suction time SK1 is a parameter related to the suction speed. Figure 5 shows the evaluation results showing the relationship between the suction delay time DL1 and the suction time SK1. The suction delay time DL1 in Figure 5 is the suction delay time DL1 (0.2 seconds to 0.35 seconds) for the A judgment when the closing operation time CT in Figure 4 is 0.2 seconds. Note that a constant value is used for the operation amount AM1.

[0067] If the liquid level immediately after the liquid runs out is between -2 mm and 0 mm, it is rated A. If the liquid level immediately after the liquid runs out is between 0 mm and 2 mm, it is rated B. The B rating is also considered to be within a usable range. In this regard, the B rating may be deemed unusable. If the B rating is deemed usable, the range of the liquid level immediately after the liquid runs out, which indirectly indicates the liquid-out position, is between -2 mm and 2 mm. If the liquid level immediately after the liquid runs out is greater than 2 mm, it is rated C.

[0068] Figure 5 confirms that when the suction time SK1 is short, i.e., when suction is performed quickly, the function for adjusting the liquid cut-off position works sufficiently. It also confirms that the width (period) of the range between A and B judgments is approximately 0.2 to 0.25 seconds. Note that when the suction time SK1 is in the range of C judgment, the timing of suctioning the processing liquid becomes slower, and the function for adjusting the liquid cut-off position is not performed, resulting in the same operation as the usual suck-back operation for adjusting the liquid level position.

[0069] According to this embodiment, in order to adjust the liquid cut-off position, the suck-back valve 18 performs the first suction operation in conjunction with the closing operation of the on-off valve 17. This makes it possible to easily adjust the liquid cut-off position, thereby easily aligning the liquid cut-off position with the tip surface of the nozzle 8 and its vicinity. Furthermore, by being able to easily adjust the liquid cut-off position, it is possible to prevent the occurrence of uneven film thickness and coating due to poor liquid cut-off conditions.

[0070] Furthermore, when adjusting the liquid cut-off position, the control unit 20 adjusts the liquid cut-off position to the height of the tip surface of the nozzle 8 and its vicinity. When the liquid cut-off position is adjusted to the tip surface of the nozzle 8 and its vicinity, for example, it is possible to suppress variations in the amount of treatment liquid discharged from the nozzle 8, thereby preventing film thickness unevenness caused by poor liquid cut-off.

[0071] Furthermore, after adjusting the liquid cut-off position, the control unit 20 controls the suck-back valve 18 to perform a second suction operation, thereby adjusting the liquid level of the treatment liquid inside the nozzle 8. That is, the control unit 20 performs a two-stage suction operation. The first suction operation is used to adjust the liquid cut-off position, and the second suction operation is used to adjust the liquid level of the treatment liquid inside the nozzle 8. Example 2

[0072] Next, a second embodiment of the present invention will be described with reference to the drawings. Note that descriptions that overlap with those of the first embodiment will be omitted. Fig. 6 is a timing chart for explaining the operation of the substrate processing apparatus 1 according to the second embodiment.

[0073] 3 of the first embodiment, when adjusting the liquid-cut position, the control unit 20 causes the suck-back valve 18 to start the first suction operation at time t5 when the closing operation of the on-off valve 17 is completed. In contrast, in the second embodiment, when adjusting the liquid-cut position, the control unit 20 may cause the suck-back valve 18 to start the first suction operation within a preset period SA from time t5 when the closing operation of the on-off valve 17 is completed. In this way, the liquid-cut position is adjusted.

[0074] In Fig. 4, for example, when the closing operation time CT of the on-off valve 17 is 0.2 seconds, there is a wide range between the A judgment and the B judgment (or the A judgment) of the suction delay time DL1. Therefore, as shown in Fig. 6, the first suction operation is performed within a preset period SA from time t5 when the closing operation of the on-off valve 17 is completed. Note that in Fig. 6, the first suction operation starts at time t51 within the period SA. Furthermore, the period SA is determined by experiment, like the range between the A judgment and the B judgment (or the A judgment) shown in Fig. 4.

[0075] According to this embodiment, the liquid-out position can be easily adjusted, as in the first embodiment. Furthermore, the function of adjusting the liquid-out position can be activated without starting the first suction operation at the time when the closing operation of the on-off valve 17 is completed. In other words, a timing range for starting the first suction operation can be secured to activate the function of adjusting the liquid-out position. Example 3

[0076] Next, a third embodiment of the present invention will be described with reference to the drawings. Note that descriptions that overlap with those of the first and second embodiments will be omitted. Fig. 7 is a timing chart for explaining the operation of the substrate processing apparatus 1 according to the third embodiment.

[0077] In Fig. 3 of Example 1, when adjusting the liquid-cut position, the control unit 20 causes the suck-back valve 18 to start the first suction operation at time t5 when the closing operation of the on-off valve 17 is completed. In contrast, in Example 3, as shown in Fig. 7, when adjusting the liquid-cut position, the control unit 20 may cause the suck-back valve 18 to start the first suction operation while the on-off valve 17 is closing, and may end the first suction operation after the closing operation is completed. In this way, the liquid-cut position is adjusted.

[0078] Furthermore, in Example 1, a high-viscosity processing liquid was used. In this example, a processing liquid with a medium viscosity (for example, 65 cP) is used. The high-viscosity processing liquid has a large inertial force and moves even when the on-off valve 17 is completely closed. Therefore, even if the first suction operation is performed a little later after the on-off valve 17 is completely closed, the function of adjusting the liquid-out position works sufficiently (see the width of the range of determination A in FIG. 4 and the period SA in FIG. 6).

[0079] In contrast, a processing liquid with a lower viscosity than a high-viscosity processing liquid is smoother and has a faster response. Therefore, when the on-off valve 17 is completely closed, the processing liquid stops quickly. Therefore, the period during which the liquid is fluid is short. Therefore, even if the suck-back valve 18 starts the first suction operation while the on-off valve 17 is closing, the function of adjusting the liquid cut-off position works sufficiently. Therefore, a width in the timing of starting the first suction operation can be secured to activate the function of adjusting the liquid cut-off position.

[0080] According to this embodiment, the liquid cut-off position can be easily adjusted, as in embodiment 1. A width of the start timing of the first suction operation can be secured in order to activate the function of adjusting the liquid cut-off position.

[0081] The present invention is not limited to the above-described embodiment, but can be modified as follows.

[0082] (1) In the above-described Example 1, the treatment liquid was a treatment liquid with a high viscosity (for example, 325 cP), and the treatment liquid in the above-described Example 3 was a treatment liquid with a medium viscosity (for example, 65 cP). The viscosity of the treatment liquid may be a medium or high viscosity of approximately 45 cP to 500 cP. Furthermore, the treatment liquid may be a treatment liquid with a viscosity other than approximately 45 cP to 500 cP.

[0083] When a highly viscous processing liquid is used, it is preferable that the control unit 20, when adjusting the liquid cut-off position, causes the suck-back valve 18 to start the first suction operation within a preset period SA from time t5 when the closing operation of the on-off valve 17 is completed. When a highly viscous processing liquid is used, the liquid cut-off position can be easily adjusted.

[0084] Furthermore, when using a medium- or low-viscosity processing liquid, it is preferable that, when adjusting the liquid cut-off position, the control unit 20 causes the suck-back valve 18 to start the first suction operation while the on-off valve 17 is closing, and ends the suction operation after the closing operation is completed. When using a medium- or low-viscosity processing liquid, the liquid cut-off position can be easily adjusted.

[0085] (2) In the above-described embodiments and variant example (1), the second suction operation is started after the suction delay time DL2, which is the time from the end of the first suction operation t6 to the preset time t7, has elapsed, as shown in Fig. 3. However, as shown in Fig. 8, the second suction operation may be started at the end of the first suction operation t6. In other words, in this case, the suction delay time DL2 is 0 seconds.

[0086] However, it is preferable that the speed of the second suction operation is slower than that of the first suction operation. If the speed of the second suction operation is as fast as that of the first suction operation (for example, if the suction time SK1 is 0.1 seconds), droplets may separate from the sucked processing liquid and adhere to the inner wall of the internal flow path 8A of the nozzle 8, potentially becoming a particle source.

[0087] Furthermore, if the first and second suction operations are performed consecutively, the liquid may not be drained reliably. Therefore, as shown in Figure 3, it is preferable to start the second suction operation after a suction delay time DL2 has elapsed, which is the time from the end of the first suction operation t6 to a preset time t7.

[0088] (3) In the above-described embodiments and modifications, the substrate processing apparatus 1 includes a single suck-back valve 18. However, as shown in FIG. 9 , the substrate processing apparatus 1 may include a suck-back valve 71 in addition to the suck-back valve 18. The suck-back valve 71 is provided in the pipe 12 between the nozzle 8 and the suck-back valve 18. The locations of the two suck-back valves 18 and 71 may be reversed.

[0089] Each of the two suck-back valves 18, 71 may be driven by an electric motor or may be driven by gas. A speed controller or an electro-pneumatic regulator may be used for each of the suck-back valves 18, 71 that are driven by gas.

[0090] In this modified example, the control unit 20 may cause the suck-back valve 18 to perform the first suction operation, and the second suck-back valve 71 to perform the second suction operation. The two roles may also be reversed. That is, the control unit 20 may cause the second suck-back valve 71 to perform the first suction operation, and the suck-back valve 18 to perform the second suction operation.

[0091] (4) In each of the above-described embodiments and modifications, the control unit 20 adjusted the liquid cut-off position to the height of the tip surface of the nozzle 8. This adjustment was performed using the liquid level position after the liquid cut-off, which indirectly indicates the liquid cut-off position. In this regard, the substrate processing apparatus 1 may be configured to include a high-speed camera capable of photographing the vicinity of the tip of the nozzle 8, and the control unit 20 to measure the liquid cut-off position from images taken by the high-speed camera. Note that the high-speed camera has a frame rate (frames / second) that allows for precise measurement of the liquid cut-off position.

[0092] (5) In the above-described embodiments and modifications, for example, in FIG. 3, the control unit 20 performed the first suction operation and the second suction operation using the suck-back valve 18 in conjunction with the closing operation of the on-off valve 17. In this regard, if the second suction operation for sucking back is not necessary, the control unit 20 may perform only the first suction operation without performing the second suction operation.

[0093] (6) In the above-described embodiments and modifications, the substrate processing apparatus 1 shown in Fig. 1 includes the pump 14. In addition to the pump 14, the substrate processing apparatus 1 may include another pump in the pipe 12 between the filter 15 and the on-off valve 17. That is, the substrate processing apparatus 1 may include two or more pumps.

[0094] (7) In the above-described embodiments and modifications, for example, a photoresist liquid and an SOG liquid are used as the processing liquid. However, the processing liquid is not limited to these. For example, a solvent, a developer, a rinse liquid, an etching liquid, or a cleaning liquid may be used as the processing liquid. For example, a thinner may be used as the solvent. For example, pure water such as deionized water (DIW) or a surfactant rinse liquid may be used as the rinse liquid.

[0095] The etching solution may be, for example, hydrofluoric acid (HF), a mixture of hydrofluoric acid (HF) and nitric acid (HNO3), or TMAH (tetramethylammonium hydroxide). The cleaning solution may be, for example, SC1, SC2, or SPM. SC1 is a mixture of ammonia, hydrogen peroxide (H2O2), and water. SC2 is a mixture of hydrochloric acid (HCl), hydrogen peroxide (H2O2), and water. SPM is a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). [Explanation of symbols]

[0096] 1... Substrate processing equipment 8 … nozzle 12...Plumbing 17...Shut-off valve 18,71 ... Suckback valve 20...Control section 23,43 ... diaphragm 71 ... Suckback valve CT … Closing operation time DL1 … Suction delay time AM1…Amount of movement SK1 … Suction time SA … Period

Claims

1. 1. A processing liquid supply method for a substrate processing apparatus including: a nozzle that discharges a processing liquid; a pipe connected to the nozzle; an on-off valve provided in the pipe; and a suck-back valve provided in the pipe between the nozzle and the on-off valve, a discharge stopping step of stopping the discharge of the treatment liquid from the nozzle by closing the on-off valve; a liquid break position adjusting step of adjusting a liquid break position, which is a position where the treatment liquid discharged in a columnar form from the nozzle is interrupted, by causing the suck-back valve to perform a suction operation in conjunction with the closing operation of the on-off valve; a liquid level position adjusting step of adjusting a liquid level of the treatment liquid, which is a downstream end position of the treatment liquid present in the flow path in the nozzle, by causing the suck-back valve to perform a second suction operation after the liquid cut-off position adjusting step; Equipped with The processing liquid supply method, wherein the speed of the suction operation in the liquid cut-off position adjusting step is faster than the speed of the second suction operation in the liquid surface position adjusting step.

2. 2. The processing liquid supply method according to claim 1, The processing liquid supply method is characterized in that the liquid break position adjusting step adjusts the liquid break position to a height of a tip surface of the nozzle.

3. In the treatment liquid supply method according to claim 1, A processing liquid supply method characterized in that the second suction operation in the liquid level position adjustment process is started after a delay time has elapsed from the end of the suction operation in the liquid run-out position adjustment process to a predetermined time.

4. In the treatment liquid supply method according to any one of claims 1 to 3, The liquid-out position adjusting step adjusts the liquid-out position by causing the suck-back valve to start the suction operation within a predetermined period from the point at which the closing operation of the on-off valve is completed.

5. A treatment liquid supply method according to any one of claims 1 to 3, The liquid-out position adjusting step adjusts the liquid-out position by causing the suck-back valve to start a suction operation while the on-off valve is performing the closing operation, and by ending the suction operation after the closing operation is completed.

6. a nozzle for discharging a treatment liquid; A pipe connected to the nozzle; an on-off valve provided in the piping; a suck-back valve provided in the piping between the nozzle and the on-off valve; A control unit; a second suck-back valve provided in the piping between the nozzle and the on-off valve; Equipped with the control unit causes the on-off valve to perform a closing operation to stop the discharge of the treatment liquid from the nozzle; the control unit controls the suck-back valve to perform a suction operation in conjunction with the closing operation of the on-off valve, thereby adjusting a liquid break-off position, which is a position where the treatment liquid discharged in a columnar form from the nozzle is broken; After adjusting the liquid cut-off position, the suck-back valve is caused to perform a second suction operation, thereby adjusting a liquid level position of the treatment liquid, which is a downstream end position of the treatment liquid present in the flow path within the nozzle; The sucking operation is performed by the suck-back valve, and the second suck-back operation is performed by the second suck-back valve. A substrate processing apparatus comprising:

7. A nozzle for discharging a treatment liquid; A pipe connected to the nozzle; an on-off valve provided in the piping; a suck-back valve provided in the piping between the nozzle and the on-off valve; a control unit, the control unit causes the on-off valve to perform a closing operation to stop the discharge of the treatment liquid from the nozzle; the control unit controls the suck-back valve to perform a suction operation in conjunction with the closing operation of the on-off valve, thereby adjusting a liquid break-off position, which is a position where the treatment liquid discharged in a columnar form from the nozzle is broken; After adjusting the liquid cut-off position, the suck-back valve is caused to perform a second suction operation, thereby adjusting a liquid level position of the treatment liquid, which is a downstream end position of the treatment liquid present in the flow path within the nozzle; a speed of the suction operation for adjusting the liquid cut-off position being adjusted to be faster than a speed of the second suction operation for adjusting the liquid level position;

8. In the substrate processing apparatus according to claim 7, the suck-back valve is a single suck-back valve; The control unit controls the single suck-back valve to perform the suction operation and the second suction operation.

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