JP2017194080A - Processing liquid supply device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing liquid supply device capable of keeping a prevention of leakage by eliminating a clearance between a valve body and a valve seat and at the same time capable of restricting deformation of a contact part between the valve body and the valve seat as much as possible and provide its control method.SOLUTION: After a diaphragm 47 acting as a valve body is moved in its closing direction to contact with a valve seat of an opening or closing valve, a working current supplied to the motor is controlled in such a way that a current value Ar flowing at a motor winding of a stepping motor may be coincided with a pushing pressure management current value Ath that is pre-determined in response to the pushing pressure of the diaphragm 47. That is, since the motor always generates a pre-determined rotational torque in a closing direction under the closed state, the diaphragm 47 is always pushed against the valve seat under a pre-determined pressure. Accordingly, if a clearance is generated at the contact part between the diaphragm 47 and the valve seat, the motor is rotated in compliance with this phenomenon. In addition, the pushing pressure management current value Ath is properly set to enable a pushing force of the diaphragm 47 against the valve seat to become low.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a processing liquid supply apparatus that supplies a processing liquid to a substrate such as a semiconductor substrate, a glass substrate for liquid crystal display, a glass substrate for a photomask, and an optical disk substrate, and a control method thereof.

  As a substrate processing apparatus for processing a substrate, there are a coating apparatus for forming a coating film of a photoresist solution on a substrate and a developing apparatus for discharging and developing a developing solution on a coated film after exposure. Each of the coating device and the developing device includes a processing liquid supply device for supplying a processing liquid. The processing liquid supply apparatus includes a discharge nozzle that discharges the processing liquid, a processing liquid supply source, and a pipe for sending the processing liquid from the processing liquid supply source to the discharge nozzle. This pipe is provided with a pump and an on-off valve. The on-off valve supplies and stops the processing liquid from the discharge nozzle.

  Regarding this on-off valve, for example, Patent Document 1 describes a valve control device that controls the flow rate of liquid. Patent Document 1 describes a technique for searching for the origin of a valve closing position. The valve control device includes a liquid flow path, a valve that opens and closes the flow path, a stepping motor (pulse motor) that drives the valve, a rotary encoder that detects a detection pulse corresponding to the rotation angle of the stepping motor, and a drive pulse And a control device for supplying the stepping motor to the stepping motor.

  The search for the origin of the valve closing position is performed as follows. The valve is driven in the closing direction, the drive pulse and the detection pulse are monitored, and a case where a detection pulse corresponding to the drive pulse cannot be obtained is determined as a step-out state. Thereafter, the valve is driven in the closing direction with a predetermined driving pulse number N from the valve position in that state, and further, the valve is driven in the opening direction with a driving pulse number M smaller than the driving pulse number N. The position thus obtained is taken as the origin of the closing position. The valve is closed by holding the valve body at the origin position thus obtained (that is, supplying a predetermined stop current to the stepping motor).

JP 2004-348227 A

However, the conventional apparatus having such a configuration has the following problems.
That is, when the on-off valve is opened and closed, the contact portion between the valve body and the valve body that receives the valve body in the processing liquid flow path is slightly deformed with the use time and the use frequency. As a result, even if the on-off valve is closed, a gap may be formed between the valve body and the valve seat, and the processing liquid may leak. According to the valve control device described in Patent Document 1, the origin position changes according to the gap generated between the valve body and the valve seat by periodically searching for the origin of the closing position, so that leakage is prevented. Can be suppressed. However, the valve body is held at the origin position obtained by the previous origin search after the origin search is performed until the next origin search is performed. If there is a gap between them, there is a problem that the processing liquid leaks.

  In order to avoid the above problem, it is necessary to frequently perform an origin search. However, according to the technique described in Patent Document 1, each time the origin is searched, the valve body is driven in the closing direction by a predetermined number N of driving pulses. Since the operating current at this time is relatively large, the valve body strongly contacts the valve seat. As a result, another problem arises in that the contact portion between the valve body and the valve seat is likely to be deformed.

  The present invention has been made in view of such circumstances, and can prevent leakage by preventing a gap from being formed between the valve body and the valve seat. It is an object of the present invention to provide a treatment liquid supply apparatus and a control method thereof that can suppress deformation of the contact portion as much as possible.

In order to achieve such an object, the present invention has the following configuration.
That is, a processing liquid supply apparatus according to the present invention includes a processing liquid flow path for circulating a processing liquid, an on-off valve having a valve body for opening and closing the processing liquid flow path, a stepping motor for moving the valve body, A driving unit that supplies a current to the stepping motor and drives the stepping motor; and a current value detection unit that detects a current value flowing in the motor winding of the stepping motor, and the driving unit supplies the stepping motor to the stepping motor. By supplying an operating current, the valve body is moved in the closing direction, and after the valve body contacts the valve seat of the on-off valve, the current value detected by the current value detection unit is the valve body. The operating current supplied to the stepping motor is controlled so as to match a predetermined pressing pressure management current value according to the pressing pressure.

  According to the processing liquid supply apparatus of the present invention, after the valve body moves in the closing direction and contacts the valve seat of the on-off valve, the value of the current flowing through the motor winding of the stepping motor becomes the pressing force of the valve body. Accordingly, the operating current supplied to the stepping motor is controlled so as to coincide with a predetermined pressing pressure management current value. That is, in the closed state of the on-off valve, the stepping motor always generates a predetermined rotational torque in the closing direction, so that the valve body is always pressed against the valve seat with a predetermined pressing pressure. Therefore, even if there is a gap in the contact portion between the valve body and the valve seat, the stepping motor rotates accordingly. As a result, the valve body moves in the closing direction and fills the gap, so that leakage from the contact portion can be prevented. Further, by appropriately setting the pressing pressure management current, the force with which the valve body presses the valve seat can be reduced, so that deformation of the contact portion between the valve body and the valve seat can be suppressed as much as possible.

  The processing liquid supply apparatus further includes a rotation amount detection unit that detects a rotation amount of the stepping motor, and the drive unit is configured to detect the valve based on the rotation amount detected by the rotation amount detection unit. It is preferable to monitor the movement distance of the body and control the operating current supplied to the stepping motor so that the valve element moves a predetermined distance. Thereby, a valve body can be moved to arbitrary positions.

  Further, in the processing liquid supply apparatus described above, the driving unit monitors the moving speed of the valve body based on the rotation amount detected by the rotation amount detecting unit, and the moving speed of the valve body is determined in advance. It is preferable to control the operating current supplied to the stepping motor so that the speed becomes high. Thereby, the valve body can be moved at an appropriate speed.

  In the processing liquid supply apparatus described above, the driving unit compares the current value detected by the current value detection unit with the pressure management current value, and the current value detected by the current value detection unit is It is preferable to determine that the valve body is in contact with the valve seat when the pressing pressure management current value is exceeded. When the valve body moves in the closing direction and contacts the valve seat, the load on the stepping motor increases and the current flowing in the motor winding increases. Therefore, when the current value detected by the current value detection unit exceeds the pressing pressure management current value, it can be appropriately determined that the valve body has contacted the valve seat.

  Further, in the processing liquid supply apparatus described above, a conversion mechanism that is provided between the stepping motor and the valve body, and converts the rotation of the stepping motor into a linear movement of the valve body; It is preferable to include a coupling that is provided between the conversion mechanism and the valve body and elastically deforms so that the valve body can be inclined with respect to the conversion mechanism. Even when the valve body and the valve seat are in contact with each other in the closed state, the coupling acts as a spring and the valve body is tilted, making it easy to suppress the gap between the valve body and the valve seat. Become.

  Further, the control method of the processing liquid supply apparatus according to the present invention includes a processing liquid flow path for circulating the processing liquid, an on-off valve having a valve body for opening and closing the processing liquid flow path, and a stepping motor for moving the valve body. And a control unit for supplying a current to the stepping motor and driving the stepping motor, and a current value detecting unit for detecting a current value flowing in the motor winding of the stepping motor. A method in which the driving unit supplies an operating current to the stepping motor to move the valve body in a closing direction, and determines that the valve body is in contact with a valve seat of the opening / closing valve. And a current value detected by the current value detection unit after the valve body is determined to have come into contact with the valve seat of the on-off valve is a predetermined pressing pressure according to the pressing pressure of the valve body. Management To match the value, and it is characterized in that it comprises a and a step of controlling the operating current supplied to the stepping motor.

  According to the control method of the processing liquid supply apparatus according to the present invention, it is determined whether the valve body is in contact with the valve seat of the on-off valve while the operating current is supplied to the stepping motor and the valve body moves in the closing direction. To do. When it is determined that the valve body has come into contact with the valve seat, stepping is performed so that the current value detected by the current value detection unit matches the pressure management current value determined in advance according to the pressure of the valve body. The operating current supplied to the motor is controlled. That is, when the valve element comes into contact with the valve seat, the load of the stepping motor increases, so that the value of the current flowing through the motor winding increases rapidly. Therefore, the operating current supplied to the stepping motor is controlled so that the value of the current flowing through the motor winding matches the predetermined pressure management current value. This suppresses excessive current from flowing through the motor winding. By matching (that is, limiting) the current value flowing through the motor winding to the pressing pressure management current value, the valve element is always pressed against the valve seat with a predetermined pressing pressure in the closed state. Therefore, even if a gap occurs at the contact portion between the valve body and the valve seat, the valve body moves in the closing direction and fills the gap. As a result, leakage from the contact portion between the valve body and the valve seat can be prevented. Moreover, the force which a valve body presses a valve seat can be made small by setting a pressing pressure management electric current suitably. As a result, the deformation of the contact portion between the valve body and the valve seat can be suppressed as much as possible.

  According to the processing liquid supply apparatus and the control method thereof according to the present invention, the valve body is always pressed against the valve seat with a predetermined pressing pressure in the closed state. Therefore, even if a gap occurs at the contact portion between the valve body and the valve seat, the valve body moves in the closing direction and fills the gap. As a result, leakage from the contact portion between the valve body and the valve seat can be prevented. Moreover, the force which a valve body presses a valve seat can be made small by setting a pressing pressure management electric current suitably. As a result, the deformation of the contact portion between the valve body and the valve seat can be suppressed as much as possible.

1 is a schematic configuration diagram of a substrate processing apparatus according to Embodiment 1. FIG. It is a figure which shows the on-off valve which concerns on Example 1. FIG. It is a figure which shows a stepping motor, a drive circuit, and those peripheral structures. It is a flowchart which shows the opening / closing operation | movement of an on-off valve. (A)-(c) is the elements on larger scale for demonstrating the opening / closing operation | movement of an on-off valve. It is a figure which shows the change of the detected electric current value in the downward process of a diaphragm. It is a figure which shows the coupling of the on-off valve which concerns on Example 2. FIG. (A) is a figure which shows the coupling of the other on-off valve which concerns on Example 2. FIG. (B) is a figure which shows the mode of a deformation | transformation of a coupling.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a substrate processing apparatus.

<Configuration of substrate processing apparatus>
Please refer to FIG. The substrate processing apparatus 1 includes a holding rotation unit 2 that holds and rotates the substrate W in a substantially horizontal posture, and a processing liquid supply unit 3 that supplies a processing liquid. As the processing solution, for example, a coating solution such as a photoresist solution, a developing solution, a solvent, or a rinse solution such as pure water is used. The processing liquid supply unit 3 corresponds to the processing liquid supply apparatus of the present invention.

  The holding rotation unit 2 includes, for example, a spin chuck 4 that holds the back surface of the substrate W by vacuum suction, and a rotation driving unit 5 that is configured by a motor or the like by rotating the spin chuck 4 about a rotation axis AX in a substantially vertical direction. I have. A cup 6 that can move up and down is provided around the holding rotation unit 2 so as to surround the side of the substrate W.

  The processing liquid supply unit 3 includes a discharge nozzle 11 that discharges the processing liquid to the substrate W, a processing liquid supply source 13 that includes a tank that stores the processing liquid, and the processing liquid supply source 13 to the discharge nozzle 11. And a processing liquid pipe 15 for feeding the processing liquid. A pump P and an on-off valve 17 are interposed in the processing liquid pipe 15 in order from the processing liquid supply source 13. The pump P is for sending the processing liquid to the discharge nozzle 11. The on-off valve 17 supplies the processing liquid and stops supplying the processing liquid. In addition, you may interpose another structure in the process liquid piping 15. FIG. For example, a filter (not shown) may be interposed between the pump P and the on-off valve 17.

  The on-off valve 17 includes a stepping motor 19 that moves the valve body. Further, the processing liquid supply unit 3 includes a drive circuit 21 that drives the stepping motor 19 and a power source 23 that is, for example, an AC power source. The drive circuit 21 adjusts the power supplied from the power source 23 and supplies a current to the stepping motor 19.

  The discharge nozzle 11 is provided downstream of the on-off valve 17. The discharge nozzle 11 is connected to the on-off valve 17 through a processing liquid pipe 15. The discharge nozzle 11 is moved to an arbitrary position by the nozzle moving mechanism 25. For example, the nozzle moving mechanism 25 moves the discharge nozzle 11 between a standby pot 27 that waits for the discharge nozzle 11 and a discharge position above the substrate W. The standby pot 27 is disposed outside the holding rotation unit 2. The nozzle moving mechanism 25 includes a support arm, a motor, a guide, and the like.

  The processing liquid supply unit 3 includes a main control unit 31 configured by a central processing unit (CPU) and the like, and an operation unit 33 for operating the substrate processing apparatus 1. The main control unit 31 controls each component of the substrate processing apparatus 1. The operation unit 33 includes a display unit such as a liquid crystal monitor, a storage unit such as a ROM (Read-only Memory), a RAM (Random-Access Memory), and a hard disk, and an input unit such as a keyboard, a mouse, and various buttons. I have. The storage unit stores conditions for controlling the on-off valve 17 and other substrate processing conditions.

<Open / close valve>
FIG. 2 is a view showing the on-off valve 17. The on-off valve 17 switches the flow of the processing liquid to a distribution state or a cutoff state by an opening / closing operation. The on-off valve 17 includes a valve chamber (valve box) 40 that is a hollow box-shaped member, and a processing liquid channel 41 provided in the valve chamber 40. The on-off valve 17 includes an upstream joint portion 42 and a downstream joint portion 43 attached to the valve chamber 40.

  The processing liquid channel 41 is used to distribute the processing liquid in the valve chamber 40. The processing liquid channel 41 includes an upstream channel 44, a valve chamber channel 45, and a downstream channel 46. The upstream channel 44, the valve chamber channel 45, and the downstream channel 46 are connected in series. The upstream joint portion 42 connects the processing liquid pipe 15a (15) and the upstream flow path 44, and the downstream joint section 43 includes the downstream flow path 46 and the processing liquid pipe 15b (15). Are connected.

  The on-off valve 17 includes a diaphragm 47 that is a valve body, a piston (valve rod) 48, and a valve seat 49. The diaphragm 47 is provided in the valve chamber 40. The peripheral edge of the diaphragm 47 is fixed to the side wall in the valve chamber 40. The center portion of the diaphragm 47 is fixed to the lower end portion of the piston 48. The piston 48 is provided to be slidable in the vertical direction of FIG. The valve seat 49 is provided at the bottom center of the valve chamber passage 45. The valve seat 49 receives the diaphragm 47.

  When the piston 48 is raised, the diaphragm 47 rising together with the piston 48 is separated from the valve seat 49 (state shown by a solid line in FIG. 2). Thereby, the processing liquid flows through the processing liquid channel 41. That is, the processing liquid channel 41 is opened by the on-off valve 17. On the other hand, when the piston 48 is lowered, the diaphragm 47 that is lowered together with the piston 48 comes into close contact with the valve seat 49 (a state indicated by a dotted line in FIG. 2). As a result, the valve chamber flow path 45 and the downstream flow path 46 are blocked, and the flow of the processing liquid from the valve chamber flow path 45 to the downstream flow path 46 is stopped. That is, the processing liquid channel 41 is closed by the on-off valve 17.

  The on-off valve 17 includes a conversion mechanism 50. The conversion mechanism 50 is provided between the rotating shaft 51 of the stepping motor 19 and the rotor 53 described later, the diaphragm 47 and the piston 48. The conversion mechanism 50 converts the rotation of the rotating shaft 51 into the linear movement of the diaphragm 47 and the piston 48 in the vertical direction. The conversion mechanism 50 includes, for example, a screw shaft, a nut that meshes with the screw shaft, and a guide portion that guides one of the screw shaft and the nut in the vertical direction (both are not shown).

<Stepping motor and drive circuit>
FIG. 3 is a diagram showing the configuration of the stepping motor 19, the drive circuit 21, and their periphery. The stepping motor 19 includes a rotor 53 and motor windings (hereinafter simply referred to as “coils”) 54a and 54b. The rotor 53 is rotatably supported. The rotor 53 is fixed to the rotating shaft 51 and rotates integrally with the rotating shaft 51. The rotor 53 is composed of, for example, a permanent magnet. The coils 54a and 54b are provided as a stator. A current is passed through the coils 54a and 54b to excite the coils 54a and 54b. Thereby, at least one of the attractive force and the repulsive force is generated in the coils 54a and 54b and the rotor 53, and the rotor 53 is rotated.

  The drive circuit 21 adjusts the power supplied from the power source 23 and supplies a current to the stepping motor 19. A current value supplied to the stepping motor 19 (a general operating current value and a stop current value, as well as a pressing pressure management current value characteristic in the present embodiment) is input or stored in the operation unit 33, and is used as a main control. Given through part 31. The current value is controlled by the drive circuit 21 according to the operating state of the on-off valve 17. The drive circuit 21 increases or decreases the current value by, for example, a PWM control method.

  In addition, the drive circuit 21 includes a switch 56a for flowing current through the coil 54a and a switch 56b for flowing current through the coil 54b. The drive control unit 57 generates a drive pulse signal based on the operation command given from the main control unit 31, and repeatedly turns the switches 56a and 56b on and off in order. As a result, the coils 54a and 54b are sequentially supplied with current and excited, and the rotor 53 rotates.

  The drive circuit 21 includes a drive control unit 57 that controls ON / OFF of the switches 56a and 56b, current value adjustment, and the like. The drive control unit 57 is configured by a CPU or the like. The drive control unit 57 performs position control and speed control of the stepping motor 19 based on the rotation amount detection signal from the rotary encoder 63. Further, the drive control unit 57 controls the current value applied to the stepping motor 19 based on the detected current value Ar from the current value detecting unit 59. These controls will be described in detail later. The drive circuit 21 or the drive control unit 57 corresponds to the drive unit of the present invention.

  The drive circuit 21 includes a current value detection unit 59. The current value detection unit 59 is provided in the wiring 61 for flowing a current through the coils 54a and 54b. The current value detection unit 59 detects the value of current flowing through the coils 54 a and 54 b of the stepping motor 19 (hereinafter referred to as “detected current value Ar” as appropriate). The current value detection unit 59 includes, for example, a hall element or a resistor.

  A rotary encoder 63 is attached to the stepping motor 19. The rotary encoder 63 detects the rotation amount (or rotation angle) of the rotor 53 of the stepping motor 19. The rotary encoder 63 outputs a pulse signal (rotation amount detection signal) as the rotation amount. The rotary encoder 63 corresponds to the rotation amount detection unit of the present invention.

<Operation of substrate processing apparatus>
Next, the operation of the substrate processing apparatus 1 will be described. Please refer to FIG. A transport mechanism (not shown) transports the unprocessed substrate W onto the spin chuck 4 of the holding rotation unit 2. The spin chuck 4 sucks and holds the back surface of the substrate W. The nozzle moving mechanism 25 moves the discharge nozzle 11 from the standby pot 27 to the discharge position above the substrate W. The holding rotation unit 2 rotates the substrate W at a preset timing, rotation speed, or the like based on the substrate processing conditions. At the same time, the processing liquid supply unit 3 discharges the processing liquid from the discharge nozzle 11 toward the substrate W.

  The operation of discharging and stopping the processing liquid is performed by the on-off valve 17. Here, the operation (in particular, the closing operation) of the on-off valve 17 will be described with reference to the flowchart of FIG.

[Step S01] Setting the diaphragm 47 to the open position h1 When the on-off valve 17 is open, the diaphragm 47 of the on-off valve 17 is in the open position h1, as shown in FIG. At this time, a stop current is supplied to the stepping motor 19. Thus, the diaphragm 47 is held at the open position h1 by a holding force corresponding to the stop current. That is, the diaphragm 47 is located away from the valve seat 49. As a result, the processing liquid flows through the processing liquid channel 41 and the processing liquid is discharged from the discharge nozzle 11.

  A predetermined amount of processing liquid is discharged from the discharge nozzle 11 in a state where the diaphragm 47 is in the open position h1. Thereafter, the on-off valve 17 closes the processing liquid channel 41. At this time, the closing operation described in steps S02 to S04 is performed.

[Step S02] Moving the diaphragm 47 in the closing direction The drive control unit 57 of the drive circuit 21 generates a drive pulse based on the operation command from the main control unit 31 to rotate the rotor 53 of the stepping motor 19 in the closing direction. . When the rotor 53 is rotated, the conversion mechanism 50 converts the rotation of the rotor 53 into a downward linear movement shown in FIG. 2, FIG. As a result, the diaphragm 47 is lowered. The diaphragm 47 descends from the open position h1 toward a virtual reference position h0 that is set below the actual closed position h2 (see FIG. 5C).

  The drive control unit 57 performs the following position control as the diaphragm 47 moves downward. When the diaphragm 47 starts to descend, a rotation amount detection signal is given from the rotary encoder 63 to the drive control unit 57. The drive control unit 57 counts the rotation amount detection signal and grasps the current position of the diaphragm 47. The drive control unit 57 gives an operating current corresponding to the drive pulse to the stepping motor 19 until the diaphragm 47 reaches a predetermined target position (the reference position h0 in the case of the closing operation).

  Further, the drive control unit 57 performs the following speed control as the diaphragm 47 moves downward. The drive control unit 57 calculates the descending speed of the diaphragm 47 by differentiating the count value of the rotation amount detection signal with respect to time. When the descending speed is not a predetermined speed, the operating current supplied to the stepping motor 19 is increased or decreased to control the diaphragm 47 to descend at a predetermined speed.

[Step S03] Has the diaphragm 47 contacted the valve seat 49?
As shown in FIG. 5B, while the diaphragm 47 is moving downward, the drive control unit 57 monitors whether the diaphragm 47 has contacted the valve seat 49. Specifically, the drive control unit 57 determines that the diaphragm 47 is in contact with the valve seat 49 when the detected current value Ar detected by the current value detecting unit 59 exceeds the pressing pressure management current value Ath. The pressing pressure management current value Ath is set in advance according to the pressing pressure of the diaphragm 47 against the valve seat 49.

  FIG. 6 shows how the detected current value Ar changes when the on-off valve 17 is in the closing operation. When the drive control unit 57 applies an operating current to the stepping motor 19, the diaphragm 47 is lowered. While the diaphragm 47 is descending (before contact with the valve seat 49), the load for the downward movement of the diaphragm 47 is relatively small, so the detected current value Ar is smaller than the pressing pressure management current value Ath (Ar <Ath). When the diaphragm 47 comes into contact with the valve seat 49, the load for the downward movement of the diaphragm 47 increases rapidly, so the detected current value Ar increases rapidly. In this embodiment, when the detected current value Ar exceeds the pressing pressure management current value Ath, it is determined that the diaphragm 47 is in contact with the valve seat 49.

[Step S04] Pressing pressure management control of the diaphragm 47 (operating current is controlled so that the detected current value Ar matches the pressing pressure management current value Ath)
Until it is determined that the diaphragm 47 is in contact with the valve seat 49, a normal operating current (operating current increased or decreased by the descending speed) is applied to the stepping motor 19, and the diaphragm 47 continues to move downward. Then, after it is determined that the diaphragm 47 has contacted the valve seat 49, the pressure management control of the diaphragm 47 is executed as follows. The drive control unit 57 controls the operating current applied to the stepping motor 19 so that the detection current value Ar detected by the current value detection unit 59 matches the pressing pressure management current value Ath. That is, the operating current supplied to the stepping motor 19 is limited after the diaphragm 47 contacts the valve seat 49. The pressure management current value Ath is appropriately determined according to the strength of the force with which the diaphragm 47 presses the valve seat 49 downward after the diaphragm 47 contacts the valve seat 49. When the drive control unit 57 controls the operating current, the diaphragm 47 is pressed against the valve seat 49 with a force corresponding to the pressing pressure management current value Ath. As a result, the leakage of the processing liquid from the contact portion between the diaphragm 47 and the valve seat 49 can be prevented.

  Here, if the pressing pressure management current value Ath is large, the force with which the diaphragm 47 presses the valve seat 49 increases accordingly, which is preferable in preventing leakage. However, if the pressing force is too strong, the contact portion between the diaphragm 47 and the valve seat 49 is likely to be deformed. Therefore, it is not preferable that the pressing pressure management current value Ath is excessive. The normal operating current supplied when the diaphragm 47 is moved downward is set to about 0.2 A at the maximum load, for example. On the other hand, the pressing force management current value Ath is set to a low current value of about 0.05 to 0.1 A, for example. The appropriate pressing pressure management current value Ath is preferably determined by experiment.

  After the diaphragm 47 comes into contact with the valve seat 49, the drive control unit 57 always monitors the detected current value Ar so as to coincide with the pressing pressure management current value Ath. If the contact portion between the diaphragm 47 and the valve seat 49 is deformed and a gap is generated between the diaphragm 47 and the valve seat 49, the load for the downward movement of the diaphragm 47 is reduced, so that the detected current value Ar is also reduced. . In the closed state, the stepping motor 19 is supplied with an operating current corresponding to the pressing pressure management current value Ath, and the pressing force is constantly applied to the diaphragm 47. Therefore, the diaphragm 47 moves downward so as to follow the generated gap. Then, it contacts the valve seat 49. As a result, the detected current value Ar increases again and is maintained at the pressing pressure management current value Ath. As described above, while the on-off valve 17 is in the closed state, the operating current is controlled so that the detected current value Ar becomes the pressing pressure management current value Ath. As a result, since the diaphragm 47 is always pressed against the valve seat 49 with a predetermined pressure, a gap is hardly generated between the diaphragm 47 and the valve seat 49. As described above, according to the present embodiment, it is possible to suppress the occurrence of leakage due to the deformation of the contact portion between the diaphragm 47 and the valve seat 49.

  After the processing liquid is discharged onto the substrate W and the substrate processing is performed, the nozzle moving mechanism 25 moves the discharge nozzle 11 from the discharge position above the substrate W to the standby pot 27. Further, the holding rotation unit 2 releases the holding of the substrate W in the rotation stopped state. A transport mechanism (not shown) transports the substrate W from the holding rotating unit 2 to the next process apparatus.

  As described above, according to this embodiment, when the on-off valve 17 is closed, the operating current is controlled so that the detected current value Ar of the coils 54a and 54b becomes the predetermined pressing pressure management current value Ath. As a result, the diaphragm 47 is always pressed against the valve seat 49 with a force corresponding to the pressing pressure management current value Ath. Therefore, even if there is a gap between the diaphragm 47 and the valve seat 49, the stepping motor 19 rotates following the clearance to lower the diaphragm 47 and contact the valve seat 49. Therefore, a leak between the diaphragm 47 and the valve seat 49 can be effectively prevented. In addition, by setting the pressing pressure management current value Ath to an appropriate current value lower than the normal operating current value, the pressing force of the diaphragm 47 is set to a relatively small force, and the contact portion between the diaphragm 47 and the valve seat 49 Can be suppressed as much as possible.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. In addition, the description which overlaps with Example 1 is abbreviate | omitted.

  In the first embodiment, as shown in FIG. 2, a piston 48 is provided between the conversion mechanism 50 and the diaphragm 47. In this regard, in the second embodiment, a coupling 71 (or 72) and pistons 73a and 73b are interposed between the conversion mechanism 50 and the diaphragm 47 as shown in FIGS.

  Specifically, the coupling 71 of FIG. 7 is sandwiched between an upper piston 73a and a lower piston 73b. One end of the coupling 71 is connected to the upper piston 73a, and the other end of the coupling 71 is connected to the lower piston 73b. The upper piston 73a is connected to the conversion mechanism 50 so as to be movable in the vertical direction. Further, the lower piston 73 b is connected to the diaphragm 47.

  The coupling 71 is configured such that the diaphragm 47 can be inclined with respect to the conversion mechanism 50. The coupling 71 is elastically deformed like a spring. The coupling 71 of FIG. 7 is provided with a slit 75. Due to the slit 75, the coupling 71 can be easily bent as indicated by a symbol K in FIG.

  FIG. 8A is a diagram showing another coupling 72. The coupling 72 in FIG. 8A includes three shaft members 77a to 77c, two plate members 79a and 79b, and a deformable member 81 that is elastically deformed. The shaft member 77a is connected to the upper piston 73a, and the shaft member 77c is connected to the lower piston 73b. Note that the three shaft members 77a to 77c, the two plate members 79a and 79b, and the deformable member 81 that is elastically deformed are connected in the order shown in FIG. FIG. 8B shows how the coupling 72 is deformed.

  The piston 48 (see FIG. 2) may be inclined obliquely without being orthogonal to the diaphragm 47 due to an error in processing the member of the on-off valve 17 or an assembly error. As a result, the diaphragm 47 may come into contact with the valve seat 49 in an inclined state, and a gap may be generated between the diaphragm 47 and the valve seat 49 to cause leakage. According to this embodiment, even when the upper piston 73a is inclined in the closed state, the couplings 71 and 72 are elastically deformed to absorb the inclination of the upper piston 73a. It is always orthogonal to the diaphragm 47. Therefore, it becomes easy to suppress the gap between the diaphragm 47 and the valve seat 49.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, as shown in FIG. 1, the processing liquid pipe 15 between the pump P and the discharge nozzle 11 is provided with an opening / closing valve 17. In this regard, the processing liquid pipe 15 between the pump P and the discharge nozzle 11 may be provided with an on-off valve 17 and a suck-back valve. The suck back valve is provided downstream of the on-off valve 17.

  (2) In Example 1, it was determined that the diaphragm 47 was in contact with the valve seat 49 when the current value Ar detected by the current value detection unit 59 exceeded the pressing pressure management current value Ath. However, the method for determining that the diaphragm 47 is in contact with the valve seat 49 is not limited to this. For example, when the diaphragm 47 moves in the closing direction, the count value of the rotation detection signal of the rotary encoder 63 is monitored, and the diaphragm 47 contacts the valve seat 49 by detecting the time point when the count value stops changing. It may be determined that

  (3) In each embodiment and each modification described above, the drive control unit 57 is based on the rotation amount (rotation amount detection signal) detected by the rotary encoder 63 when moving the diaphragm 47 in the closing direction. The moving speed of the diaphragm 47 is monitored. The drive control unit 57 controls the operating current supplied to the stepping motor 19 so that the moving speed of the diaphragm 47 becomes a predetermined speed. Thereby, the diaphragm 47 could be moved at an appropriate speed.

  In this regard, the drive control unit 57 may monitor the moving distance based on the rotation amount, and may control the operating current so as to move a predetermined distance. For example, the operating current may be increased or decreased as follows. If the movement distance (realized position) based on the rotation amount is less than the predetermined distance (scheduled current position), the smaller the error between the predetermined distance and the movement distance based on the rotation amount, the smaller the operating current As the error increases, the operating current increases. Alternatively, the operating current is increased as the moving distance based on the rotation amount is smaller than the predetermined distance, and the operating current is decreased as the distance is larger. When the operating current is increased, the torque applied to the rotor 53 of the stepping motor 19 increases. Thereby, the diaphragm 47 can be moved to an arbitrary position.

DESCRIPTION OF SYMBOLS 3 ... Process liquid supply part 11 ... Discharge nozzle 17 ... On-off valve 19 ... Stepping motor 21 ... Drive circuit 31 ... Main control part 41 ... Process liquid flow path 47 ... Diaphragm 50 ... Conversion mechanism 57 ... Drive control part 59 ... Current value detection Part 63 ... Rotary encoder 71, 72 ... Coupling

Claims (6)

A treatment liquid flow path for circulating the treatment liquid;
An on-off valve having a valve body for opening and closing the treatment liquid channel;
A stepping motor for moving the valve body;
A drive unit for supplying current to the stepping motor and driving the stepping motor;
A current value detection unit for detecting a current value flowing in the motor winding of the stepping motor;
With
The drive unit moves the valve body in a closing direction by supplying an operating current to the stepping motor, and the current value detection unit detects after the valve body contacts the valve seat of the on-off valve. A processing liquid supply device for controlling an operating current supplied to the stepping motor so that a current value to be matched with a pressing pressure management current value determined in advance according to the pressing pressure of the valve body . The processing liquid supply apparatus according to claim 1, wherein the apparatus further includes:
A rotation amount detection unit for detecting the rotation amount of the stepping motor;
The drive unit monitors the movement distance of the valve body based on the rotation amount detected by the rotation amount detection unit, and supplies the valve body to the stepping motor so that the valve body moves a predetermined distance. A processing liquid supply device that controls an operating current to be applied. In the processing liquid supply apparatus according to claim 2,
The driving unit monitors the moving speed of the valve body based on the rotation amount detected by the rotation amount detecting unit, and the stepping motor is set so that the moving speed of the valve body becomes a predetermined speed. A processing liquid supply device for controlling an operating current supplied to the substrate. In the processing liquid supply apparatus in any one of Claim 1 to 3,
The drive unit compares the current value detected by the current value detection unit with the pressure management current value, and the current value detected by the current value detection unit exceeds the pressure management current value. The processing liquid supply device that determines that the valve body is in contact with the valve seat. The processing liquid supply apparatus according to claim 1, wherein the apparatus further includes:
A conversion mechanism that is interposed between the stepping motor and the valve body, and converts the rotation of the stepping motor into linear movement of the valve body;
And an elastically deformable coupling provided between the conversion mechanism and the valve body and capable of tilting the valve body with respect to the conversion mechanism. Treatment liquid supply device. A treatment liquid flow path for circulating the treatment liquid;
An on-off valve having a valve body for opening and closing the treatment liquid channel;
A stepping motor for moving the valve body;
A drive unit for supplying current to the stepping motor and driving the stepping motor;
A current value detection unit for detecting a current value flowing in the motor winding of the stepping motor;
A processing liquid supply apparatus comprising:
A process in which the driving unit moves the valve body in a closing direction by supplying an operating current to the stepping motor;
Determining that the valve body has contacted the valve seat of the on-off valve;
After determining that the valve body has contacted the valve seat of the on-off valve, the current value detected by the current value detection unit becomes a pressure management current value determined in advance according to the pressure of the valve body. Controlling the operating current supplied to the stepping motor to match,
A method for controlling a processing liquid supply apparatus, comprising:

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