JP2011023669A - Process liquid supplying device and process liquid supplying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To monitor flow rate of process liquid and to trap air bubbles in the process liquid using the same apparatus when discharging the process liquid to a substrate from a sending part through a supply nozzle. <P>SOLUTION: The process liquid supplying device includes a first flow path which opens at the upper part of an airtight vessel, for sending process liquid through a sending part; a second flow path which is connected to the bottom part of the vessel, with an opening/closing valve provided in the middle; a photoelectric sensor of which optical axis is so formed as to cross the drooping locus of a droplet dropped from the first flow path; a flow rate monitoring part which measures flow rate of the process liquid based on the detection signal from the photoelectric sensor; an exhaust path which is provided to the upper part of the vessel and opens to the atmosphere through an exhaust valve; and a control part which monitors whether a liquid level in the vessel has reached a lower limit level, and when the lower limit level is reached, closes the opening/closing valve and releases the exhaust valve so that the process liquid is sent into the vessel from the sending part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field in which a processing liquid is supplied from a delivery unit to a substrate via a supply nozzle.

  As one of semiconductor manufacturing apparatuses, there is an apparatus that supplies a processing liquid to the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer) or a glass substrate for a flat panel display and performs liquid processing. As this type of apparatus, a resist coating apparatus for forming a resist film on a substrate, a developing apparatus for supplying a developer to a substrate after exposure, and an insulating film forming apparatus for supplying a solution containing a precursor of an insulating film to the substrate and so on.

  As a method for supplying the processing liquid in these liquid processing apparatuses, the processing liquid is sucked from the processing liquid tank by, for example, a suction-type pump, and the processing liquid is supplied from the pump to the surface of the substrate through the supply nozzle by a predetermined amount. Has been done. By the way, in this type of liquid processing apparatus, the flow rate of the processing liquid is not monitored. The reason is that it is difficult to detect the flow rate with high accuracy because the flow rate is very small and the viscosity of the treatment liquid is various. Further, on the downstream side of the pump, it is required to simplify the flow path as much as possible in order to suppress the generation and contamination of bubbles in the processing liquid. For example, a thermal type flow meter has a drawback that the flow path becomes complicated, and furthermore, heat is applied to the processing liquid, so that it is not suitable for the liquid processing apparatus.

However, if the processing liquid is not discharged or the flow rate deviates from the set value due to a failure of a valve or the like provided in the flow path, a serious problem occurs in the process for the substrate, and the substrate becomes defective, and the subsequent process The substrate will also be defective. Further, the flow path of the processing liquid in the liquid processing apparatus is provided with a filter and a bubble trap for removing bubbles in the processing liquid in addition to the valve, and there are problems such as a large number of devices.
Patent Documents 1 to 3 describe that a falling liquid droplet is detected by a photoelectric sensor, but does not describe reducing the number of devices in the treatment liquid supply line.

JP-A-6-63135 JP-A-8-229119 JP-A-11-190675

  The present invention has been made in view of such circumstances, and the object thereof is to monitor the flow rate of the processing liquid when discharging the processing liquid from the delivery unit to the substrate via the supply nozzle. It is an object of the present invention to provide a technique capable of performing monitoring and trapping of bubbles in the processing liquid using the same device.

The present invention provides a processing liquid supply apparatus provided between a processing liquid delivery unit and a supply nozzle for discharging the delivered processing liquid to a substrate.
An airtight container,
A first flow path that opens to an upper portion in the container and from which the processing liquid is sent out from the sending-out portion;
When the processing liquid is supplied into the container from the first flow path, the processing liquid corresponding to the liquid amount is pushed out from the container and sent to the nozzle side so that it is connected to the bottom of the container and is opened and closed in the middle A second flow path provided with a valve;
A photoelectric sensor in which an optical axis is formed so as to cross a drop trajectory of the droplet in order to detect a droplet dropped from the first flow path into the container;
A flow rate monitoring unit for measuring the flow rate of the processing liquid based on a detection signal from the photoelectric sensor;
An exhaust path provided at the top of the container and opening to the atmosphere via an exhaust valve;
Monitoring whether the liquid level in the container has reached the lower limit level, and when detecting that the lower limit level has been reached, close the opening and closing valve of the second flow path and open the exhaust valve; And a control unit that outputs a control signal so as to send the processing liquid from the delivery unit into the container so that the liquid level in the container becomes a preset level.

Another invention is a process liquid supply method for delivering a process liquid from a process liquid delivery unit and discharging the treatment liquid from a supply nozzle to a substrate.
A treatment liquid is dropped from the upper part into the airtight container via the first flow path from the delivery part, and the treatment liquid corresponding to the liquid amount is pushed out from the container and connected to the bottom of the container. A step of being sent to the supply nozzle through the flow path of
Measuring a flow rate of the processing liquid based on a detection signal from a photoelectric sensor in which an optical axis is formed so as to cross a drop trajectory of the droplet in the container;
Monitors whether the liquid level in the container has reached the lower limit level, and closes the open / close valve of the second flow path and connects to the upper part of the container when detecting that the lower limit level has been reached And a step of sending the processing liquid from the delivery section into the container so that the liquid level in the container reaches a preset level.

  According to the present invention, when the processing liquid is discharged from the delivery unit to the substrate through the supply nozzle, the droplets dropped in the container provided on the downstream side of the delivery unit are detected by the photoelectric sensor. The liquid flow rate can be monitored. While the processing liquid is pushed downstream by the amount of the processing liquid dripped into the container, when the liquid level in the container reaches the lower limit level, the exhaust path connected to the upper part of the container is opened to the atmosphere. Since the processing liquid is sent into the container from the sending part and the liquid level is thereby raised to the set level, the flow rate can be monitored and the bubbles in the processing liquid can be trapped by the same device. . For this reason, there is an effect that the number of devices can be reduced and the supply channel can be simplified.

It is a block diagram of the liquid processing apparatus which concerns on embodiment of this invention. It is a vertical side view of the flow measurement part provided in the said liquid processing apparatus. It is a block diagram of the control part provided in the said liquid processing apparatus. It is a flowchart of the liquid level control of the resist liquid in the container of the said flow control part. It is explanatory drawing which showed a mode that the liquid level in the said container was adjusted. It is explanatory drawing which showed a mode when the said droplet fell. It is a wave form diagram output from a photoelectric sensor when the said droplet falls. It is the graph which showed the relationship between the time interval and flow volume in a memory | storage part.

An embodiment in which the processing liquid supply apparatus according to the present invention is applied to a liquid processing apparatus including a liquid processing module that performs resist coating will be described. FIG. 1 is a configuration diagram showing the overall schematic configuration of the liquid processing apparatus 10. First, the liquid processing module will be briefly described. In the liquid processing module 40, a spin chuck 42 for horizontally holding a semiconductor wafer (hereinafter referred to as a wafer) W, which is a substrate, is stored in a cup body 41. The spin chuck 42 is rotated and driven by a drive mechanism 43. It can be moved up and down. In addition, a discharge port 44 is provided at the bottom of the cup body 41 for discharging excess resist solution that has not been applied to the wafer W in a drain or mist state.
A supply nozzle 45 is provided above the cup body 41. The supply nozzle 45 is configured to be able to discharge the resist solution to the center of the wafer W held by the spin chuck 42 while being supported by the arm 45a.

  Next, the processing liquid supply apparatus 10 for supplying a resist liquid as a processing liquid to the supply nozzle 45 will be described from the upstream side. In FIG. 1, 11 is a chemical solution (resist solution) bottle, 12 is a pressurized gas source, 13 is a buffer tank, 14 is a filter, 15 is a pump, and 3 is a flow rate measuring unit. V1 to V5 are valves, and 21a is a degassing flow path. When an inert gas such as nitrogen gas is supplied from the pressurized gas source 12 into the chemical bottle 11 via the pipe 21, the chemical liquid in the chemical bottle 11 is pushed out and the buffer tank is supplied via the pipe 22. 13 is supplied. One end side of a pipe 23 is connected to the bottom surface of the buffer tank 13, and the other end side of the pipe 23 is connected via a filter 14 to a suction pump 16 corresponding to a processing liquid delivery unit. The chemical solution in the buffer tank 13 is sucked into the pump 16 by the suction operation of the pump 16 of the type.

  The flow rate measuring unit 3 is connected to the downstream side of the pump 16 via a first supply pipe 24 that is a first supply path. The supply nozzle 45 is connected to the downstream side of the flow rate measuring unit 3 through a second supply pipe 25 that is a second supply path. The second supply pipe 25 is provided with a suck back valve 25a and an air operated valve 25b. The suck back valve 25a has a role of generating a negative pressure in the suction chamber by a vacuum pressure or the like when the resist solution is not discharged, and drawing the tip surface of the resist solution from the tip of the supply nozzle 45.

  Next, the flow rate measuring unit 3 will be described in detail. As shown in FIG. 2, the flow rate measuring unit 3 includes, for example, a cylindrical airtight container 31 that temporarily stores the resist solution R. The above-described first supply pipe 24 is inserted into and connected to the center of the ceiling of the container 31, and the tip of the first supply pipe 24 is configured as a constricted portion whose diameter decreases downward. Yes. Therefore, the downstream end of the first supply pipe 24 is open at the top of the container 31. The upstream end of the second supply pipe 25 that forms the second supply path is connected to the bottom of the container 31. Since the inside of the container 31 is in an airtight state, when the resist solution R is supplied from the first supply pipe 24 to the inside 31 of the container, the pressure in the container 31 increases, so that the resist solution R in the container 31 becomes the second It is pushed out to the supply pipe 25. That is, it is pushed out from the container 31 to the second supply pipe 25 by the amount of liquid supplied from the first supply pipe 24 into the container 31.

  The flow rate measuring unit 3 is intended to obtain the amount of the resist solution flowing through the first supply pipe 24 based on the droplet detection result, for example, the number of droplets per unit time. A combination of parameters including the discharge pressure of 15, the diameter of the discharge port of the first supply pipe 24, the viscosity of the resist solution, and the like satisfy the condition that the liquid drops from the first supply pipe 24 into the container 31. It turns out that. That is, since the viscosity and flow rate of the resist solution are set, the discharge port of the first supply pipe 24 is supplied as a droplet group from the first supply pipe 24 into the container 31 under these conditions. This means that the diameter and the discharge pressure of the pump 15 are determined.

  Then, in order to detect a droplet dropped from the first supply tube 24, for example, on the extension line of the central axis of the first supply tube 24 so that the optical axis 33c crosses the drop trajectory of the droplet. A light emitting unit 33a and a light receiving unit 33b constituting the photoelectric sensor 33 are provided on the side of the container 31 across the container 31 so as to cross (cross, for example, orthogonally cross). The height position of the optical axis 33c is, for example, in the vicinity of the discharge port of the first supply pipe 24 and separated from the discharge port so that the liquid droplet passing through the optical axis 33c does not contact the liquid surface.

  By the way, in the resist solution R, gas such as nitrogen gas dissolved at the time of storage in the chemical solution tank 11 or the buffer tank 13 is dissolved and added as when pushed out from the first supply pipe 24 into the container 31. The dissolved gas may appear as bubbles when released from the pressure state. When bubbles are generated in the resist solution R in this manner, the bubbles rise in the liquid pool region in the container 31 and repel at the liquid level, increasing the volume of the gas phase region in the container 31, and as a result, the resist solution R The liquid level decreases. Therefore, one end of an exhaust pipe 32 is connected to the upper surface of the container 31 in order to extract gas from the container 31, and the other end side of the exhaust pipe 32 is open to the atmosphere. An exhaust valve V4 comprising an open / close valve is provided in the middle of the exhaust pipe 32. When the exhaust valve V4 is closed, the inside of the container 31 is in an airtight atmosphere, and when the exhaust valve V4 is open, it is opened to the atmosphere. It becomes a state.

  As described above, when the accumulated amount of bubbles in the resist solution R increases while the inside of the container 31 remains airtight, the level of the resist solution R continues to decrease. (Lower liquid level) is set. Specifically, a lower limit level detection unit 34 including a photoelectric sensor that forms a horizontal optical axis 34c in the container 31 at a height position of the lower limit liquid level is provided. Further, as will be described later, when the level of the resist solution R reaches the lower limit value, the exhaust valve V4 is opened and the resist solution R is supplied from the first supply pipe 24 into the container 31, whereby the level of the solution is reduced. Although it rises, its upper liquid level is set. In other words, an upper limit level detection unit including a photoelectric sensor that forms a horizontal optical axis 35c in the container 31 at the height position of the upper limit liquid level is provided. The photoelectric sensor constituting the lower limit level detection unit 34 or the upper limit level detection unit 35 is provided on the side of the container 31. The container 31 is made of, for example, a resin, but when a transparent material is not used, a portion through which the optical axes 33c to 35c of the photoelectric sensors 33 to 35 pass is made of a transparent member.

  FIG. 3 is a configuration diagram illustrating a part related to the control system of the processing liquid supply apparatus 10. The control unit 8 including a computer includes a flow rate monitoring program 81, a storage unit 82, a liquid level control program 83, an alarm generation unit 84, and a CPU 85. Reference numeral 86 denotes a data bus. A counter unit 87 counts the number of pulses of the droplet detection signal from the photoelectric sensor. More specifically, the counter unit 87 compares a received light signal (analog voltage) from the light receiving unit 33b of the photoelectric sensor with a threshold value, and a pulse that appears when the received light signal falls below the threshold value. A counter for counting is provided, and the count number is sent to the control unit 8. The threshold value is set to a value that can determine whether or not the droplet has blocked the optical axis. In this example, the flow rate monitoring unit is configured by the counter unit 87 and the flow rate monitoring program 81, but the pulse count function in the counter unit 87 may be provided as software in the flow rate monitoring program 81.

  The storage unit 82 stores a reference value for the volume of droplets dropped from the first supply pipe 24 into the container 31 and a correction value for this reference value. The reference value is, for example, the droplet volume (design value) assumed in the design stage, and the correction value is, for example, the ratio between the regularly measured droplet volume (measured value) and the design value. That is, actual measurement value / reference value. For example, assuming that one drop of the resist solution is 1/50 ml, the reference value is used. At this time, 50 drops of the resist solution is 1.0 ml. When 50 drops of the resist solution are actually collected with a graduated cylinder, the measured value is 1. If it is 1 ml, the correction value is 1.1 / 1.0 = 1.1. The correction value is updated to new information when the operator periodically measures the resist solution and rewrites data in the storage unit 82 of the computer.

  The flow rate monitoring program 81 uses the above-described reference value, correction value, and count number of droplets per second, and uses the calculation formula (correction value × reference value × count number / second) to calculate the flow rate measurement unit 3. The flow rate of the resist solution flowing through is calculated, and the calculation result is compared with the flow rate set value. The flow rate set value is the discharge amount (supply amount) of the pump 15 per unit time set according to the process recipe. The flow rate monitoring program 81 issues a signal to the alarm generation unit 84 when the calculated flow rate of the resist solution exceeds the allowable range from the flow rate set value. The alarm generation unit 84 corresponds to, for example, an alarm sound generation unit or an alarm lamp lighting unit, but “generate an alarm” in the present invention includes a case where an alarm is displayed on the operation panel.

Here, a specific example of the relationship between the resist solution supply flow rate and the number of pulses will be described. For example, if the droplet volume is about 0.1 ml and the flow rate is 1 ml / sec, the pulse count is 10 counts / second. When the flow rate is 0.4 ml / sec, the pulse count is 3 to 4 counts. If the volume of the droplet is about 0.03 ml, the count number is about three times that of the case of about 0.1 ml, and the flow rate detection resolution is about three times larger. The volume of the droplet decreases as the diameter of the discharge port of the first supply path 32 decreases. The size of the diameter is selected based on the range of the flow rate used, the viscosity of the resist solution, and the like.
If the discharge pressure and the aperture size are the same, the droplet size differs depending on the viscosity of the resist solution. Therefore, the correction value is as described above for each type of resist solution (type of chemical component or dilution rate with a solvent). Thus, it can obtain | require based on actual measurement and can memorize | store it in a memory | storage part.

  The liquid level control program 83 is a program for adjusting the liquid level of the resist liquid when gas is accumulated in the container 31, and a group of steps is executed so as to execute the flow shown in FIG. Is assembled. These programs are installed in the control unit 8 by, for example, a flexible disk, hard disk, MD, memory card, flash memory, or the like.

  Next, the operation of the above embodiment will be described. Now, it is assumed that the resist solution in the buffer tank 13 is sucked into the suction pump 15 of the processing solution supply apparatus 10 as described above. Then, after the wafer W as a substrate is placed on the spin chuck 42 shown in FIG. 1 by a transfer arm (not shown), the supply nozzle 45 is positioned above the center portion of the wafer W, and the spin chuck 42 is rotated. In this state, the suction state of the suck valve 25a is opened and the operating valve 25b is opened, and the discharge operation of the pump 15 is performed. As a result, the resist solution in the first supply pipe 24 is discharged to form droplets and falls in the container 31 of the flow rate measuring unit 3, and as described above, the same amount of resist solution as the droplets is stored in the first supply tube 24. 2 is discharged from the supply pipe 25 to the center of the wafer W through the supply nozzle 45. This resist solution spreads around the periphery of the wafer W by centrifugal force, and a liquid film of the resist solution is formed on the surface of the wafer W. (Spin coated).

  At this time, since the optical axis 33c of the photoelectric sensor 33 is blocked by the droplet, the level of the received light signal is lowered. Therefore, the received light signal is binarized and further processed by a logic circuit, so that the droplet moves the optical axis. A pulse is obtained each time the signal is blocked, and the number of pulses is counted by the counter unit 87. The flow rate monitoring program 81 calculates the average discharge flow rate (average flow rate per unit time) from the supply nozzle 45 as described above based on the count value per unit time, the reference value of the volume per drop, and the correction value. Then, the calculated flow rate is compared with the set flow rate as a flow rate measurement value, and when the difference is out of the allowable range, the alarm generation unit 84 is caused to perform an alarm generation operation. As processing after the alarm is generated, for example, it is possible to stop the discharge of the resist solution and stop the rotation of the wafer W and perform maintenance. For example, although the difference is outside the allowable range, If it is within the determined range, the wafer W in the same lot including the wafer W is subjected to the coating process, and then the wafer W that has been subjected to the coating process in an alarmed state is subjected to film thickness inspection. You may make it take correspondence, such as performing.

  The flow rate measuring unit 3 also monitors the liquid level in the container 31 simultaneously with the measurement of the flow rate of the resist solution. This will be described with reference to the flowchart of FIG. 4 and FIG. The resist solution discharged from the first supply pipe 24 into the container 31 is released from the pressurized state. When nitrogen gas or the like is dissolved in the resist solution at this time, the dissolved gas appears as bubbles. The generated bubbles rise in the resist liquid pool in the container 31 and move to the gas phase region, the volume of the gas phase region in the container 31 increases, and the liquid level of the resist solution decreases. On the other hand, the liquid level control program 83 is executed, and the lower limit level detector 34 determines whether the level of the liquid level is the lower limit level (step S1).

When the liquid level control program 83 determines that the liquid level of the resist solution is located above the lower limit liquid level based on the light reception signal from the light receiving unit 34b of the lower limit level detection unit 34, the normal process is performed. Continued. When it is determined that the liquid level is below the lower limit liquid level, it is determined whether or not the resist liquid is being discharged onto the wafer W (step S2). If the resist solution is being discharged onto the wafer W at this time, the resist solution is subsequently discharged. Further, when the resist solution is not discharged onto the wafer W, that is, when the resist coating operation is completed, the valve 25a is closed and the exhaust valve V4 is opened, and the resist solution is discharged into the container 31 by the pump 15 (step). S3).
When the liquid level falls below the lower limit level, it is usually when the resist solution is being discharged. Therefore, it is considered that the exhaust valve V4 is often opened after the discharge is continued and completed.

  Then, the resist solution is supplied as droplets from the first supply pipe 24 into the container 31, and the gas in the container 31 flows out to the atmosphere through the exhaust pipe 32 by the volume of the supplied liquid (see FIG. 5 (a)). As a result, the level of the resist solution in the container 31 rises. At this time, based on the light reception signal from the upper limit level detector 35, the liquid level control program 83 determines whether or not the liquid level is the upper limit level (step S4). When the liquid level rises and the liquid level reaches the upper limit level (FIG. 5B). The pump 15 is stopped and the valve V4 is closed (step S5).

  According to the above-described embodiment, when the resist solution is discharged from the pump (delivery unit) 15 to the wafer W via the supply nozzle 45, the droplets dropped into the container 31 provided on the downstream side of the pump 15 are discharged. Since it is counted and detected by the photoelectric sensor 33, the flow rate of the resist solution can be monitored. Accordingly, when the resist solution is not normally discharged due to a malfunction of the pump 15 or the valve, the abnormality can be detected, which can contribute to suppressing product defects.

  Then, when the resist solution is pushed downstream by the amount of the resist solution dropped into the container 31, and when the liquid level in the container 31 reaches the lower limit level, the exhaust valve V4 is opened to evacuate the container 31 to the atmosphere. In this state, the resist solution is sent from the pump 15 into the container 31 to raise the liquid level to the set level. Therefore, the same device is used for monitoring the flow rate and trapping bubbles in the resist solution. Can be performed. That is, the flow rate measuring unit 3 also has a bubble trap function. For this reason, the number of devices in the resist solution supply path can be reduced to simplify the supply path.

  Next, another embodiment (second embodiment) will be described focusing on differences from the above-described embodiment (first embodiment). In the liquid processing apparatus according to the second embodiment, an interval (droplet interval time) at which droplets drop from the first supply tube 24 into the container 31 is obtained, and the first supply tube 24 is determined based on the drop interval. The amount of the resist solution flowing through is calculated. Hereinafter, a description will be given with reference to FIGS. FIG. 6 shows the state of the tip of each first supply pipe 24 at predetermined times t1 and t2. At time t1, the droplets M1 and M2 are dropped from the first supply tube 24 in this order, and the droplet M2 is located immediately below the optical axis 33c. In addition, at time t2, the droplet M3 that has dropped from the first supply tube 24 following the droplet M2 is in a state of being positioned immediately above the optical axis 33c. The droplet drop interval is the time from when the previous droplet passes the optical axis 33c until the later droplet reaches the optical axis 33c, for example, from time t1 to time t2.

  FIG. 7 shows a waveform of a pulse signal output from a light receiving signal of the photoelectric sensor 33 when the droplets M1 to M3 fall, and further outputted through a logic circuit included in the photoelectric sensor 33, for example. Yes. As shown in FIG. 7, the output level is “L” (low level) while the optical axis 33c is blocked by the droplet, and the drop interval of the droplet, that is, the optical axis is not blocked by the droplet. The output level becomes “H” (high level). In the second embodiment, a pulse signal as shown in FIG. 7 is transmitted to the control unit 8 without passing through the counter unit 87.

  The control unit 8 of the second embodiment is configured in the same manner as the control unit 8 of the first embodiment, and the flow rate monitoring program 81 is stepped to perform the above-described processing. The storage unit 82 of the control unit 8 stores data indicating a correspondence relationship between the drop interval of the droplets obtained by performing an experiment in advance and the flow rate of the resist in the first supply pipe 24. The correspondence relationship is shown, for example, as a graph in FIG. In this graph, the vertical axis represents the drop interval ΔT, and the horizontal axis represents the flow rate of the resist solution supplied from the first supply pipe 24.

When the discharge operation of the pump 15 is started to supply the resist solution to the wafer W (when the discharge start signal is output), the flow monitoring program 81 is created based on the light reception signal of the photoelectric sensor 33. In the pulse signal shown in FIG. 7, the “H” period is measured and a predetermined number of unit pulses, for example, 10 pulses are counted, and an average value of the “H” period of each pulse in the 10 pulses is calculated. Then, the control unit 8 reads the average value as the drop interval ΔT, reads the flow rate of the resist solution corresponding to the drop interval ΔT from the data stored in the storage unit 82, and uses the read value as a measurement value of the flow rate of the resist solution. decide. Then, when the determined measured value of the flow rate of the resist solution is out of the allowable range from the set value, the flow rate monitoring program 81 outputs an alarm as in the first embodiment. Such flow rate monitoring stops when a discharge stop signal for the pump 15 is output from the control unit 8.
Here, the average value may be obtained for each number of unit pulses for the “H” period as described above, but the “H” period obtained for each pulse without obtaining the average value is treated as the drop interval ΔT as it is. May be. The drop interval ΔT is, for example, the rising interval of “H” instead of the period of “H” in the pulse train (the next droplet has finished passing from the time when the droplet has passed with respect to the optical axis). (Interval up to the time point) or “H” falling interval (interval from the time when the liquid droplet starts to pass to the optical axis to the time when the next liquid droplet starts to pass). In the second embodiment, the same effect as in the first embodiment can be obtained. As described above, in the first embodiment, the resolution decreases when the volume of the droplet of the resist solution is large. However, in the second embodiment, the accuracy is improved even when the volume of the droplet is large. High flow rate can be measured.

  In each of the above-described embodiments, an alarm is output when the measured value of the resist solution supply flow rate is out of the allowable range or more than the set value. The discharge flow rate of the pump may be adjusted according to the difference, and the measured value may be the set value. In that case, a step of correcting the command value of the discharge speed of the drive unit of the pump 11 is added as a step executed by the flow rate monitoring program 81. The correction value is determined in advance according to the difference between the flow rate setting value and the flow rate measurement value, and is stored in the storage unit 82 in association with the difference. Then, the flow rate monitoring program 81 reads a correction value corresponding to the difference and issues an instruction to the drive unit according to the correction value. Specifically, the rotation speed command value of the drive motor of the pump 15 corresponding to the corrected discharge speed command value is output to the motor control circuit. In this way, the control unit 8 controls the resist solution supply flow rate to be the set value. Even when such control is performed, for example, if the difference from the set value is smaller than ± a1, the driving speed of the pump 15 is adjusted as described above, and if the difference is greater than ± a1, an alarm is generated. You may make it respond | correspond similarly to previous embodiment.

  In the above, the photoelectric sensor 33 for detecting the flow rate is not limited to the transmission type, and a reflection type photoelectric sensor may be used. In the case of using a reflection type photoelectric sensor, it can be realized by making the inner surface of the container 31 on the optical axis from the light emitting and receiving part a surface having a high reflectance such as a mirror surface. The upper limit liquid level detection unit and the lower limit liquid level detection unit are not limited to photoelectric sensors, and may be a liquid level gauge using a limit switch. Further, the processing solution to be used is not limited to a resist solution, and for example, a developing solution, a polyimide solution for forming a protective film, or a solution containing a precursor of an insulating film may be used.

DESCRIPTION OF SYMBOLS 10 Liquid processing apparatus 11 Chemical bottle 13 Buffer tank 15 Pump 24 1st supply pipe 25 2nd supply pipe 3 Flow rate measurement part 31 Container 33 Photoelectric sensor 33c Optical axis 34 Lower limit level detection part 35 Upper limit level detection part 40 Liquid processing module 42 Spin chuck 8 Control unit 81 Flow rate monitoring program 82 Storage unit 83 Liquid level control program 84 Alarm generation unit

Claims (10)

In the treatment liquid supply apparatus provided between the treatment liquid delivery part and the supply nozzle for discharging the delivered treatment liquid to the substrate,
An airtight container,
A first flow path that opens to an upper portion in the container and from which the processing liquid is sent out from the sending-out portion;
When the processing liquid is supplied into the container from the first flow path, the processing liquid corresponding to the liquid amount is pushed out from the container and sent to the nozzle side so that it is connected to the bottom of the container and is opened and closed in the middle A second flow path provided with a valve;
A photoelectric sensor in which an optical axis is formed so as to cross a drop trajectory of the droplet in order to detect a droplet dropped from the first flow path into the container;
A flow rate monitoring unit for measuring the flow rate of the processing liquid based on a detection signal from the photoelectric sensor;
An exhaust path provided at the top of the container and opening to the atmosphere via an exhaust valve;
Monitoring whether the liquid level in the container has reached the lower limit level, and when detecting that the lower limit level has been reached, close the opening and closing valve of the second flow path and open the exhaust valve; A processing liquid supply apparatus, comprising: a control unit that outputs a control signal so as to send the processing liquid from the sending part into the container so that the liquid level in the container becomes a preset level.   The processing liquid supply apparatus according to claim 1, wherein the flow rate monitoring unit includes an alarm generation unit that outputs an alarm when the measured flow rate deviates from a set flow rate.   The processing liquid supply apparatus according to claim 1, wherein the flow rate monitoring unit outputs a control signal so that a delivery flow rate of the delivery unit becomes a measured flow rate.   The flow rate monitoring unit counts droplets based on a detection signal from a photoelectric sensor, and determines a flow rate of the processing liquid based on a previously obtained volume of the droplet and a count number per unit time. The processing liquid supply apparatus according to any one of claims 1 to 3.   The flow rate monitoring unit stores in advance data related to the flow rate of the processing liquid and the interval time of droplets dropped from the first flow path into the container, and the detection signal from the photoelectric sensor The processing liquid supply apparatus according to claim 1, wherein an interval time is measured, and a flow rate of the processing liquid is obtained based on the measurement result and the relational data. In the process liquid supply method, the process liquid is sent out from the process liquid delivery part and discharged from the supply nozzle to the substrate.
A treatment liquid is dropped from the upper part into the airtight container via the first flow path from the delivery part, and the treatment liquid corresponding to the liquid amount is pushed out from the container and connected to the bottom of the container. A step of being sent to the supply nozzle through the flow path of
Measuring a flow rate of the processing liquid based on a detection signal from a photoelectric sensor in which an optical axis is formed so as to cross a drop trajectory of the droplet in the container;
Monitors whether the liquid level in the container has reached the lower limit level, and closes the open / close valve of the second flow path and connects to the upper part of the container when detecting that the lower limit level has been reached Supplying the processing liquid to the atmosphere, and supplying the processing liquid from the sending section into the container so that the liquid level in the container is set at a preset level. Method.   The process liquid supply method according to claim 6, further comprising a step of outputting an alarm when the measured flow rate of the process liquid deviates from the set flow rate.   8. The processing liquid supply method according to claim 6, further comprising a step of controlling the delivery flow rate of the delivery unit to be a measured flow rate.   The step of measuring the flow rate of the processing liquid is a step of counting the number of droplets based on the detection signal from the photoelectric sensor, and determining the flow rate of the processing liquid based on the previously obtained volume of the droplet and the number of counts per unit time. The process liquid supply method according to any one of claims 6 to 8, wherein   The step of measuring the flow rate of the processing liquid includes the step of measuring the interval time based on a detection signal from the photoelectric sensor, and the flow rate of the processing liquid and the interval between droplets dropped into the container from the first flow path in advance. 9. A process liquid supply method according to claim 6, further comprising a step of calculating a flow rate of the process liquid based on a measurement result and the relation data using time relation data. .

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