JP6709668B2 - Treatment liquid supply device and control method thereof - Google Patents

Description

The present invention relates to a processing liquid supply apparatus for supplying a processing liquid to a substrate such as a semiconductor substrate, a glass substrate for liquid crystal display, a glass substrate for a photomask, a substrate for an optical disk 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 the substrate and a developing apparatus for discharging a developing solution onto the exposed coating film for development. The coating device and the developing device each include a processing liquid supply device for supplying the processing liquid. The processing liquid supply device includes a discharge nozzle for discharging 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. A pump and an on-off valve are provided in this pipe. The on-off valve is for supplying and stopping 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 a liquid. Further, Patent Document 1 describes a technique for searching the origin of the valve closing position. The valve control device includes a liquid flow passage, a valve that opens and closes the flow passage, 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. To a stepping motor.

The origin search of the closed position of the valve is executed as follows. The valve is driven in the closing direction, the drive pulse and the detection pulse are monitored, and when the detection pulse corresponding to the drive pulse cannot be obtained, it is determined as a step out state. After that, 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 with the driving pulse number M smaller than the driving pulse number N in the opening direction. The position thus obtained is the origin of the closed position. By holding the valve element at the origin position thus obtained (that is, supplying a predetermined stop current to the stepping motor), the valve is closed.

JP 2004-348227 A

However, the conventional device 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 seat that receives the valve element and the valve element in the processing liquid flow path is deformed to some extent depending on the usage time and the usage frequency. As a result, even if the on-off valve is closed, a treatment liquid may leak due to a gap between the valve body and the valve seat. According to the valve control device described in Patent Document 1, the origin position of the closed position is periodically searched, and the origin position changes in accordance with the gap generated between the valve body and the valve seat. Can be suppressed. However, after the origin search is performed, the valve body is held at the origin position obtained by the previous origin search 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 problems, it is necessary to search the origin frequently. However, according to the method described in Patent Document 1, the valve element is driven in the closing direction by the predetermined driving pulse number N each time the origin is searched. Since the operating current at this time is relatively large, the valve body makes strong contact with the valve seat. As a result, another problem that the contact portion between the valve body and the valve seat is likely to be deformed occurs.

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

The present invention has the following configuration in order to achieve such an object.
That is, the processing liquid supply device for supplying the processing liquid to the substrate according to the present invention includes a processing liquid channel for circulating the processing liquid, an on-off valve having a valve body for opening and closing the processing liquid channel, and A stepping motor for moving the valve body; a drive section for supplying a current to the stepping motor to drive the stepping motor; and a current value detecting section for detecting a current value flowing in a motor winding of the stepping motor. The drive unit supplies the operating current to the stepping motor to move the valve body in the closing direction, and after the valve body comes into contact with the valve seat of the on-off valve, the current value detection unit The on- off valve can be operated by constantly controlling the operating current supplied to the stepping motor so that the detected current value matches a predetermined pressing pressure management current value according to the pressing force of the valve body. During the closed state, the stepping motor is always caused to generate a predetermined rotation torque in the closing direction so that the pressing force is always applied to the valve body .

According to the treatment liquid supply apparatus of the present invention, after the valve body moves in the closing direction and comes into contact with the valve seat of the on-off valve, the current value flowing in 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 match the preset 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 the valve body is always pressed against the valve seat with a predetermined pressing pressure. Therefore, even if a gap is created in the contact portion between the valve body and the valve seat, the stepping motor is rotated accordingly. As a result, the valve body moves in the closing direction to fill the gap, so that it is possible to prevent leakage from the contact portion. Further, by appropriately setting the pushing pressure management current, the force with which the valve body presses the valve seat can be reduced, so that the deformation of the contact portion between the valve body and the valve seat can be suppressed as much as possible.

Further, in the processing liquid supply apparatus described above, further, a rotation amount detection unit that detects the rotation amount of the stepping motor is provided, and the drive unit is based on the rotation amount detected by the rotation amount detection unit, and the valve It is preferable to monitor a moving distance of the body and control an operating current supplied to the stepping motor so that the valve body moves a predetermined distance. Thereby, the valve body can be moved to an arbitrary position.

Further, in the processing liquid supply apparatus described above, the drive 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 predetermined. It is preferable to control the operating current supplied to the stepping motor so that the speed becomes different. Thereby, the valve body can be moved at an appropriate speed.

In the treatment liquid supply device described above, the drive unit compares the current value detected by the current value detection unit and the pressing 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 pushing pressure management current value is exceeded. When the valve body moves in the closing direction and comes into contact with the valve seat, the load on the stepping motor increases and the current flowing through the motor winding increases. Therefore, when the current value detected by the current value detection unit exceeds the pushing pressure management current value, it is possible to appropriately determine that the valve body has come into contact with the valve seat.

Further, in the processing liquid supply apparatus described above, a conversion mechanism which is provided so as to be interposed between the stepping motor and the valve body, and which converts rotation of the stepping motor into linear movement of the valve body, It is preferable that a coupling provided between the conversion mechanism and the valve body and elastically deformable to tilt the valve body with respect to the conversion mechanism is provided. Even when the valve body and the valve seat contact diagonally in the closed state, the coupling functions like a spring and the valve body is tilted, so it is easy to suppress the gap between the valve body and the valve seat. Become.

Further, a method for controlling a processing liquid supply apparatus according to the present invention is a processing liquid channel for circulating a processing liquid, an on-off valve having a valve body for opening and closing the processing liquid channel, and a stepping motor for moving the valve body. And a current value detection unit that detects a current value flowing in a motor winding of the stepping motor by supplying a current to the stepping motor and driving the stepping motor. And a step of moving the valve body in a closing direction by supplying an operating current to the stepping motor by the drive unit, and the valve body is configured to open and close the valve. The process of determining that the valve body has contacted the valve seat, and 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 is the pressing force of the valve body. In accordance with the above, by always controlling the operating current supplied to the stepping motor so as to match the pressing pressure management current value, the stepping motor is always closed in the closing direction while the on-off valve is closed. Generating a predetermined rotational torque so that a pressing force is constantly applied to the valve body .

According to the control method of the treatment liquid supply apparatus of 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 is moving 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 preset pressing pressure management current value according to the pressing force of the valve body. The operating current supplied to the motor is controlled. That is, when the valve body comes into contact with the valve seat, the load on the stepping motor increases, so that the current value flowing through the motor winding suddenly increases. 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 pressing 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 with the pressing pressure control current value, 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 in the contact portion between the valve body and the valve seat, the valve body moves in the closing direction accordingly and fills the gap. As a result, it is possible to prevent leakage from the contact portion between the valve body and the valve seat. Further, by appropriately setting the pushing pressure management current, the force with which the valve body pushes the valve seat can be reduced. 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 treatment 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 in the contact portion between the valve body and the valve seat, the valve body moves in the closing direction accordingly and fills the gap. As a result, it is possible to prevent leakage from the contact portion between the valve body and the valve seat. Further, by appropriately setting the pushing pressure management current, the force with which the valve body pushes the valve seat can be reduced. 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 a first embodiment. FIG. 3 is a diagram showing an on-off valve according to the first embodiment. It is a figure which shows a stepping motor, a drive circuit, and those peripheral components. It is a flowchart which shows the opening/closing operation of an on-off valve. (A)-(c) is a partial enlarged view for explaining the opening/closing operation of an on-off valve. It is a figure which shows the change of the detected current value in the descending process of a diaphragm. FIG. 6 is a diagram showing a coupling of an on-off valve according to a second embodiment. (A) is a figure which shows the coupling of the other on-off valve which concerns on Example 2. (B) is a figure which shows the mode of deformation 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.

<Structure of substrate processing apparatus>
Please refer to FIG. The substrate processing apparatus 1 includes a holding and rotating 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 liquid, for example, a coating liquid such as a photoresist liquid, a developing liquid, a solvent, or a rinse liquid such as pure water is used. The treatment liquid supply unit 3 corresponds to the treatment liquid supply device of the present invention.

The holding and rotating 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 rotates the spin chuck 4 around a rotation axis AX in a substantially vertical direction and that is configured by a motor or the like. I have it. A cup 6 that can move up and down is provided around the holding and rotating 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 onto the substrate W, a processing liquid supply source 13 including a tank that stores the processing liquid, and the processing liquid supply source 13 to the discharge nozzle 11. And a treatment liquid pipe 15 for feeding the treatment liquid. A pump P and an opening/closing valve 17 are interposed in the treatment liquid pipe 15 in order from the treatment liquid supply source 13. The pump P is for delivering the processing liquid to the discharge nozzle 11. The on-off valve 17 supplies the processing liquid and stops the supply of the processing liquid. Other components may be interposed in the processing liquid pipe 15. For example, a filter (not shown) may be interposed between the pump P and the open/close valve 17.

The on-off valve 17 includes a stepping motor 19 that moves the valve body. The treatment liquid supply unit 3 also includes a drive circuit 21 that drives the stepping motor 19 and a power supply 23 that is, for example, an AC power supply. The drive circuit 21 adjusts the electric power supplied from the power supply 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 opening/closing valve 17 via the processing liquid pipe 15. The discharge nozzle 11 is moved to an arbitrary position by the nozzle moving mechanism 25. The nozzle moving mechanism 25 moves the discharge nozzle 11 between, for example, a standby pot 27 for waiting the discharge nozzle 11 and a discharge position above the substrate W. The standby pot 27 is arranged outside the holding rotation unit 2. The nozzle moving mechanism 25 is composed of a support arm, a motor, a guide and the like.

The processing liquid supply unit 3 includes a main control unit 31 including a central processing unit (CPU) and the like, and an operation unit 33 for operating the substrate processing apparatus 1. The main controller 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 it. The storage unit stores conditions for controlling the opening/closing valve 17 and other substrate processing conditions.

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

The treatment liquid flow path 41 allows the treatment liquid to flow in the valve chamber 40. The treatment 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 passage 44, and the downstream joint portion 43 connects the downstream flow passage 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 inside the valve chamber 40. The peripheral portion of the diaphragm 47 is fixedly provided on the side wall inside the valve chamber 40. The central portion of the diaphragm 47 is fixed to the lower end portion of the piston 48. The piston 48 is provided slidably in the vertical direction of FIG. The valve seat 49 is provided in the center of the bottom of the valve chamber flow passage 45. The valve seat 49 receives the diaphragm 47.

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

The open/close valve 17 includes a conversion mechanism 50. The conversion mechanism 50 is provided between the rotating shaft 51 of the stepping motor 19 and a rotor 53, which will be described later, and the diaphragm 47 and the piston 48. The conversion mechanism 50 converts the rotation of the rotary shaft 51 into a vertical linear movement of the diaphragm 47 and the piston 48. 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 (none of which is shown).

<Stepping motor and drive circuit>
FIG. 3 is a diagram showing a configuration of the stepping motor 19, the drive circuit 21, and their peripherals. 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. As a result, 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 electric power supplied from the power supply 23 and supplies a current to the stepping motor 19. The current value supplied to the stepping motor 19 (a general operating current value, a stop current value, and a pressing pressure control current value characteristic of this embodiment) that is input or stored in the operation unit 33 is used as the 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, the PWM control method.

The drive circuit 21 also includes a switch 56a for passing a current through the coil 54a and a switch 56b for passing a 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 ON/OFF the switches 56a and 56b 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 and adjustment of a current value. The drive controller 57 is composed of a CPU and 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 given to the stepping motor 19 based on the detected current value Ar from the current value detection 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 detector 59. The current value detector 59 is provided on the wiring 61 for passing a current through the coils 54a and 54b. The current value detection unit 59 detects a current value flowing through the coils 54 a and 54 b of the stepping motor 19 (hereinafter, appropriately referred to as “detection current value Ar”). The current value detector 59 is configured to include, 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 detector 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 transfer mechanism (not shown) transfers the unprocessed substrate W onto the spin chuck 4 of the holding and rotating unit 2. The spin chuck 4 adsorbs and holds the back surface of the substrate W. Further, 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/rotating 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 the processing liquid and stopping the discharging is performed by the opening/closing valve 17. Here, the operation (particularly, the closing operation) of the opening/closing valve 17 will be described with reference to the flowchart of FIG.

[Step S01] Setting the diaphragm 47 to the open position h1 With the open/close valve 17 open, the diaphragm 47 of the open/close valve 17 is in the open position h1 as shown in FIG. 5(a). At this time, a stop current is supplied to the stepping motor 19. As a result, the diaphragm 47 is held at the open position h1 by the holding force corresponding to the stop current. That is, the diaphragm 47 is located away from the valve seat 49. As a result, the treatment liquid flows through the treatment liquid flow path 41, and the treatment liquid is ejected from the ejection nozzle 11.

With the diaphragm 47 in the open position h1, a predetermined amount of the processing liquid is discharged from the discharge nozzle 11. After that, the open/close valve 17 closes the processing liquid flow path 41. At this time, the closing operation described in steps S02 to S04 is executed.

[Step S02] Move 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 the downward linear movement shown in FIG. 2 and FIG. As a result, the diaphragm 47 descends. The diaphragm 47 descends from the open position h1 toward a virtual reference position h0 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 descending, 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 applies 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 closing operation).

Further, the drive control unit 57 performs the following speed control with the downward movement of the diaphragm 47. The drive control unit 57 time-differentiates the count value of the rotation amount detection signal to calculate the descending speed of the diaphragm 47. When the descending speed is not the 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] Did the diaphragm 47 contact the valve seat 49?
As shown in FIG. 5B, while the diaphragm 47 is moving downward, the drive controller 57 monitors whether or not the diaphragm 47 contacts 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 detection unit 59 exceeds the pressing pressure management current value Ath. The pushing pressure management current value Ath is preset according to the pushing 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. The drive controller 57 gives an operating current to the stepping motor 19 to lower the diaphragm 47. While the diaphragm 47 is descending (before contacting 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 rapidly increases, so the detected current value Ar rapidly increases. In the present embodiment, it is determined that the diaphragm 47 is in contact with the valve seat 49 when the detected current value Ar exceeds the pressing pressure management current value Ath.

[Step S04] Pushing pressure management control of the diaphragm 47 (operating current is controlled so that the detected current value Ar matches the pushing pressure management current value Ath).
Until it is determined that the diaphragm 47 has come into contact with the valve seat 49, the stepping motor 19 is supplied with the normal operating current (the operating current increased or decreased by the descending speed), and the diaphragm 47 continues to descend. Then, after it is determined that the diaphragm 47 has come into contact with the valve seat 49, the pushing pressure management control of the diaphragm 47 is executed as follows. The drive control unit 57 controls the operating current supplied to the stepping motor 19 so that the detected current value Ar detected by the current value detection unit 59 matches the pressing pressure management current value Ath. That is, after the diaphragm 47 contacts the valve seat 49, the operating current supplied to the stepping motor 19 is limited. The pressing force control current value Ath is appropriately determined according to the strength of the force of the diaphragm 47 pressing the valve seat 49 downward after the diaphragm 47 contacts the valve seat 49. The drive control unit 57 controls the operating current, so that 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, it is possible to prevent the processing liquid from leaking from the contact portion between the diaphragm 47 and the valve seat 49.

Here, if the pushing pressure control current value Ath is large, the force with which the diaphragm 47 pushes the valve seat 49 increases accordingly, which is preferable for 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, so that it is not preferable that the pressing pressure control current value Ath becomes excessively large. The normal operating current supplied when moving down the diaphragm 47 is set to, for example, about 0.2 A at maximum load. On the other hand, the pressing pressure management current value Ath is set to a low current value of, for example, about 0.05 to 0.1 A. It is preferable that the appropriate pressing pressure control current value Ath is determined by an experiment.

After the diaphragm 47 comes into contact with the valve seat 49, the drive control unit 57 constantly monitors the detected current value Ar so as to match 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 and the detected current value Ar is also reduced. .. In the closed state, the stepping motor 19 is given an operating current according to the pressing pressure control current value Ath and the pressing force is constantly acting on the diaphragm 47, so that the diaphragm 47 moves downward so as to follow the generated gap. And 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, the operating current is controlled so that the detected current value Ar becomes the pressing pressure management current value Ath while the open/close valve 17 is closed. As a result, since the diaphragm 47 is constantly pressed against the valve seat 49 with a predetermined pressure, it is difficult to form a gap between the diaphragm 47 and the valve seat 49. As described above, according to this embodiment, it is possible to suppress the occurrence of leakage due to deformation of the contact portion between the diaphragm 47 and the valve seat 49.

After the processing liquid is discharged onto the substrate W to perform the substrate processing, 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 and rotating unit 2 releases the holding of the substrate W in the rotation stopped state. Then, the transfer mechanism (not shown) transfers the substrate W from the holding/rotating unit 2 to the apparatus for the next step.

As described above, according to this embodiment, when the opening/closing 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 constantly pressed against the valve seat 49 with a force corresponding to the pressing pressure control current value Ath. Therefore, even if a gap is created between the diaphragm 47 and the valve seat 49, the diaphragm 47 descends and comes into contact with the valve seat 49 by following the rotation of the stepping motor 19. Therefore, the leak between the diaphragm 47 and the valve seat 49 can be effectively prevented. Moreover, the pressing force management current value Ath is set to an appropriate current value lower than the normal operating current value to make the pressing force of the diaphragm 47 a relatively small force, and the contact portion between the diaphragm 47 and the valve seat 49. Can be suppressed as much as possible.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. Note that the description overlapping with that of the first embodiment will be omitted.

In the first embodiment, as shown in FIG. 2, the piston 48 is provided between the conversion mechanism 50 and the diaphragm 47. In this regard, in the second embodiment, as shown in FIGS. 7 and 8, a coupling 71 (or 72) and pistons 73a and 73b are provided between the conversion mechanism 50 and the diaphragm 47.

Specifically, the coupling 71 of FIG. 7 is sandwiched between the upper piston 73a and the 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. The lower piston 73b is connected to the diaphragm 47.

The coupling 71 is configured so that the diaphragm 47 can be tilted with respect to the conversion mechanism 50. Further, the coupling 71 elastically deforms like a spring. The coupling 71 of FIG. 7 is provided with a slit 75. The slit 75 facilitates bending of the coupling 71, as indicated by the symbol K in FIG. 7.

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

The piston 48 (see FIG. 2) may not be orthogonal to the diaphragm 47 but may be inclined obliquely due to an error in processing a member of the on-off valve 17 or an assembly error. As a result, the diaphragm 47 may contact the valve seat 49 in an inclined state, and a gap may occur between the diaphragm 47 and the valve seat 49 to cause a leak. According to the present embodiment, even when the upper piston 73a is inclined in the closed state, the couplings 71 and 72 elastically deform to absorb the inclination of the upper piston 73a, so that the lower piston 73b is 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-mentioned embodiment, but can be modified as follows.

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

(2) In the first embodiment, it is determined that the diaphragm 47 is in contact with the valve seat 49 when the current value Ar detected by the current value detection unit 59 exceeds the pressing pressure control current value Ath. However, the method of 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 when the count value stops changing, the diaphragm 47 contacts the valve seat 49. You may judge that it did.

(3) In each of the above-described embodiments and modified examples, the drive control unit 57, 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. This allowed the diaphragm 47 to move at an appropriate speed.

In this respect, the drive control unit 57 may monitor the moving distance based on the rotation amount and control the operating current so as to move the predetermined distance. For example, the operating current may be increased or decreased as follows. When the movement distance (actual current position) based on the rotation amount is less than the predetermined distance (planned current position), the smaller the error between the predetermined distance and the movement distance based on the rotation amount, the smaller the operating current. Is increased, and the operating current is increased as the error is increased. 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 moving distance is increased. In addition, when the operating current is increased, the torque applied to the rotor 53 of the stepping motor 19 is increased. Thereby, the diaphragm 47 can be moved to an arbitrary position.

3... Treatment liquid supply unit 11... Discharge nozzle 17... Open/close valve 19... Stepping motor 21... Drive circuit 31... Main control unit 41... Treatment liquid flow path 47... Diaphragm 50... Conversion mechanism 57... Drive control unit 59... Current value detection Part 63... Rotary encoder 71, 72... Coupling

Claims (6)

A processing liquid supply device for supplying a processing liquid to a substrate,
A processing liquid flow path for circulating the processing liquid,
An on-off valve having a valve body that opens and closes the processing liquid flow path,
A stepping motor for moving the valve body,
A drive unit that supplies current to the stepping motor to drive the stepping motor,
A current value detection unit for detecting a current value flowing in the motor winding of the stepping motor,
Equipped with
The drive unit supplies an operating current to the stepping motor to move the valve body in the closing direction, and after the valve body comes into contact with the valve seat of the on-off valve, the current value detection unit detects the current value. The on- off valve is closed by constantly controlling the operating current supplied to the stepping motor so that the current value to be applied matches the predetermined pressing pressure management current value according to the pressing force of the valve body. During the state, the processing liquid supply apparatus is characterized in that the stepping motor always generates a predetermined rotation torque in a closing direction so that a pressing force is constantly applied to the valve body . The processing liquid supply apparatus according to claim 1, wherein the apparatus further comprises:
A rotation amount detector 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 stepping motor so that the valve body moves a predetermined distance. A processing liquid supply device for controlling the operating current to be applied. The processing liquid supply apparatus according to claim 2,
The drive 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 adjusted so that the moving speed of the valve body becomes a predetermined speed. A processing liquid supply device that controls an operating current supplied to the processing liquid. The processing liquid supply apparatus according to any one of claims 1 to 3,
The drive unit compares the current value detected by the current value detection unit with the pressing pressure management current value, and the current value detected by the current value detection unit exceeds the pressing pressure management current value. The processing liquid supply device that determines that the valve body has come into contact with the valve seat. The processing liquid supply apparatus according to claim 1, wherein the apparatus further comprises:
A conversion mechanism that is provided so as to be interposed between the stepping motor and the valve body, and converts a rotation of the stepping motor into a linear movement of the valve body,
A coupling which is provided between the conversion mechanism and the valve body and which is elastically deformable so that the valve body can be tilted with respect to the conversion mechanism. Treatment liquid supply device. A processing liquid flow path for circulating the processing liquid,
An on-off valve having a valve body that opens and closes the processing liquid flow path,
A stepping motor for moving the valve body,
A drive unit that supplies current to the stepping motor to drive the stepping motor,
A method of controlling a processing liquid supply device, comprising: a current value detection unit that detects a current value flowing in a motor winding of the stepping motor, and supplying a processing liquid to a substrate.
A step in which the drive unit moves the valve body in a closing direction by supplying an operating current to the stepping motor;
Determining the contact of the valve element with 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 is a predetermined pressing pressure management current value according to the pressing pressure of the valve body. By constantly controlling the operating current supplied to the stepping motor so that they coincide with each other, while the opening/closing valve is in the closed state, the stepping motor always generates a predetermined rotational torque in the closing direction to cause the valve element to rotate. The process of constantly applying pressing force ,
A method for controlling a processing liquid supply apparatus, comprising:

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