JP2001340736A - Mixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mix and feed solutions containing different chemicals in a specified ratio into a supply tank. SOLUTION: A mixing device 10 supplies 50% hydrofluoric acid stored in an HF tank 11 and pure water generated by water purifying apparatus 21 to the feed tank 13 to mix at a prescribed rate, and supplies mixed solution in the feed tank 13 to a semiconductor manufacturing device 45 installed in the downstream side of the feed tank 13. A control part 19 reads and sets agitation time t according to the liquid supply capacity of the feed tank 13 and the ratio of HF liquid and the pure water from a liquid agitation database 60, before starting the supply of the mixed-solution of the HF liquid and the pure water. Because the pure water and the HF liquid replenished to the feed tank 13 are circulated through a return line 52 for stirring before being supplied to the semiconductor manufacturing device 45, their ratio becomes fixed. Also in the feed tank 13, the concentration unevenness of the mixed-solution of the pure water and the HF liquid can be eliminated so that the concentration of the whole mixed-solution can be maintained uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixing apparatus for supplying a mixed liquid used in a flat panel display manufacturing process such as a semiconductor or a liquid crystal by mixing a plurality of chemical solutions having different components.

[0002]

2. Description of the Related Art Conventionally, in a mixing apparatus for mixing chemicals having different components, an ultrasonic vortex flowmeter and an air-driven valve are incorporated in a stock solution and pure water of a chemical solution. The replenishing amount of the chemical solution is measured in accordance with the supplied pulse and sent to a chemical solution storage tank (supply tank), where the undiluted chemical solution and pure water are mixed in the chemical solution storage tank. Thereafter, the mixed liquid in the chemical storage tank is supplied to the semiconductor manufacturing apparatus.

[0003]

However, in the conventional mixing apparatus constructed as described above, when a concentrated undiluted solution is dropped into a chemical solution storage tank, the concentrated solution is sufficiently mixed with the chemical solution previously stored in the chemical solution storage tank. There is a problem that the concentrated undiluted solution falls into the drug solution in the drug solution storage tank without being diffused without being mixed.

[0004] Therefore, conventionally, the mixing time has been set long so that the drug solution (stock solution) dropped into the drug solution storage tank is sufficiently mixed with pure water. Therefore, there is a problem that it takes too much time to supply a chemical solution (mixed solution) prepared at a predetermined ratio.

Furthermore, since hydrofluoric acid has a higher specific gravity than water, the hydrofluoric acid concentration at the bottom of the chemical storage tank becomes high immediately after the completion of the first chemical liquid mixing operation, and the mixture is not sufficiently stirred. Was not stable.

Accordingly, an object of the present invention is to provide a mixing device that solves the above-mentioned problems.

In order to solve the above problems, the present invention has the following features.

According to the first aspect of the present invention, there is provided a stirring means for continuously stirring a liquid in a supply tank for a predetermined time, and a discharge provided in a mixed liquid discharge path for supplying a mixed liquid mixed in the supply tank downstream. A valve and valve control means for opening the discharge valve after a predetermined time has elapsed from the start of stirring by the stirring means, so that the mixed liquid mixed in the supply tank can be sufficiently stirred in a short time. Thus, it is possible to stably supply a uniformly mixed liquid without concentration unevenness of the mixed liquid mixed in the supply tank.

According to the second aspect of the present invention, the liquid supplied to the supply tank is circulated through a circulation path having one end connected near the bottom of the supply tank and the other end connected to another portion of the supply tank. A pump is provided, the pump is started when the liquid from each replenishment line is supplied to the supply tank by a predetermined amount or more, and after the predetermined time has elapsed, the circulation of the liquid by the pump is stopped, so that the liquid supplied to the supply tank is discharged. It can be sufficiently stirred while circulating. Further, according to the present invention, the discharge valve provided in the mixed liquid discharge path for supplying the mixed liquid mixed in the supply tank to the downstream, and the discharge valve is opened after a lapse of a predetermined time from the start of stirring by the pump. A valve control means is provided, so that the uniformly mixed liquid can be stably supplied without concentration unevenness of the mixed liquid mixed in the supply tank.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the mixing apparatus according to the present invention. As shown in FIG. 1, the mixing device 10 includes 50 HF stored in an HF tank 11.
% Hydrofluoric acid and pure water generated by the pure water producing apparatus 21 are replenished to the supply tank 13 and mixed at a predetermined ratio, and the mixed liquid mixed in the supply tank 13 is downstream of the supply tank 13. Is supplied to the semiconductor manufacturing apparatus 45 installed in the apparatus. Note that hydrofluoric acid is an aqueous solution of hydrogen fluoride (hydrogen fluoride), and is hereinafter referred to as “HF solution”.

The HF liquid stored in the HF tank 11 is H
The supply tank 13 is replenished via the F replenishment path 12. The material of the liquid contact portion of the HF replenishment path 12 is excellent in chemical resistance,
Fluorine resin with very little elution of impurities, such as PFA
(Verfluoroalkoxy copolymer).

Numeral 14 is an ultrasonic vortex flow meter for measuring HF,
The flow rate of the HF solution sent through the HF replenishment path 12 is measured.
The liquid contact part of the ultrasonic vortex flow meter 14 for HF measurement is formed of the PFA.

An air drive valve 15 for replenishing HF with a flow rate adjusting mechanism is provided downstream of the ultrasonic vortex flow meter 14 for measuring HF. The compressed air for driving the HF replenishment air drive valve 15 is supplied to the air supply passage 1 branched from the air supply passage 25.
6, it flows at a pressure in the range of about 0.5 to 0.7 MPa,
The pressure is reduced to 0.3 to 0.5 MPa by the pressure reducing valve 17.

The compressed air supplied from the air supply passage 16 is supplied to the HF supplement air drive valve 15 by the switching operation of the three-way solenoid valve 18.

The control section 19 is connected to the ultrasonic vortex flow meter 14 for HF measurement and the three-way solenoid valve 18, counts the flow pulses output from the ultrasonic vortex flow meter 14 for HF measurement, and counts the number of pulses. Accordingly, the discharge side flow path of the three-way solenoid valve 18 is controlled to be switched to the exhaust path 20 side or the pipe path 16c side.

The memory 19a of the control unit 19 has a liquid stirring database for setting a stirring time of a circulation process performed when the HF solution and the pure water are mixed in the supply tank 13, and a replenishment tank for the supply tank. A pump control program (pump control means) for starting the pump when a predetermined amount or more of liquid is supplied from the line, and controlling the pump so as to stop the circulation of the liquid by the pump after a lapse of a predetermined time;
A valve control program (valve control means) for opening the chemical liquid supply air drive valve (discharge valve) 35 after a predetermined time has elapsed from the start of circulation by the pump.

When the discharge-side flow path of the three-way solenoid valve 18 is switched to the line 16c, the HF replenishing air drive valve 15
Is opened, and when the discharge side flow path of the three-way solenoid valve 18 is switched to the exhaust path 20, the HF replenishment air drive valve 15 closes. The HF replenishment air drive valve 15 is in communication with the supply tank 13 via the HF replenishment pipeline 12b.

The pure water generated by the pure water producing apparatus 21 is supplied to the supply tank 13 through a pure water supply path 22. In addition, the pure water replenishment passage 22 has an ultrasonic vortex flowmeter 23 for measuring pure water and an air drive valve 24 for replenishing pure water with a flow rate adjusting mechanism.
Are arranged. The compressed air for driving the pure water replenishment air drive valve 24 is supplied to the air supply passage 25 from the air supply passage 25 by about 0.5 to 0.5.
It flows in at a pressure within the range of 7 MPa, and is set to 0.1 by the pressure reducing valve 17.
The pressure is reduced to 3 to 0.5 MPa.

The compressed air supplied from the air supply passage 25 is supplied to the pure water replenishment air drive valve 24 by the switching operation of the three-way solenoid valve 27.

The control unit 19 is connected to the ultrasonic vortex flowmeter 23 for measuring pure water and the three-way solenoid valve 27, counts the flow pulses output from the ultrasonic vortex flowmeter 23 for measuring pure water, and counts the number of pulses. The discharge side flow path of the three-way solenoid valve 27 is switched to the exhaust path 28 or the pipe 25b in accordance with the number of pulses to perform control.

When the discharge-side flow path of the three-way solenoid valve 27 is switched to the pipe 25b, the pure water replenishment air drive valve 24 is switched over.
Is opened, and when the discharge side flow path of the three-way solenoid valve 27 is switched to the exhaust path 28 side, the pure water replenishment air drive valve 24 is closed. The pure water replenishment air drive valve 24 is connected to the supply tank 13 via a pure water replenishment pipe 22b.

In the supply tank 13, the HF liquid is replenished by opening the HF replenishment air drive valve 15, and pure water is replenished by opening the pure water replenishment air drive valve 24, so that the HF liquid is replenished. A mixed liquid in which pure water is mixed at a predetermined ratio is generated.

The supply tank 13 has first and second liquid level sensors 36 and 37 for monitoring the liquid level of the mixed liquid. The first liquid level sensor 36 is a level gauge that detects the upper limit position of the mixed liquid, and the second liquid level sensor 37 is a level gauge that detects the lower limit position of the mixed liquid.

The mixed liquid (chemical liquid) mixed in the supply tank 13 is pressure-fed by a chemical liquid supply pump 33 and sent to a semiconductor manufacturing apparatus 45 via a supply pipe (mixed liquid discharge path) 34. On the downstream side of the chemical supply pump 33,
Air drive valve (discharge valve) for chemical liquid supply with flow rate adjustment mechanism 3
5 are provided.

A return line (circulation path) 52 for stirring is branched from a line 34 between the liquid supply pump 33 and the air supply valve 35 for supplying liquid. When the supply of the chemical solution to the supply tank 13 is completed, the chemical solution supply pump 33 is started, and the mixed solution (chemical solution) discharged from the bottom of the supply tank 13 is returned to the upper portion of the supply tank 13 through the return pipe 52 for stirring. Thus, the mixture in the supply tank 13 is stirred to make the concentration uniform.
In addition, a circulation air drive valve 53 that is opened when the liquid in the supply tank 13 is circulated and stirred is provided in the stirring return pipe line 52.

The supply tank 13 and the semiconductor manufacturing apparatus 4
A recovery pipe 59 is connected between the supply pipe 13 and the supply pipe 13 for returning the excess mixed liquid in the semiconductor manufacturing apparatus 45 to the supply tank 13. Therefore, in the supply tank 13, the HF replenishing line 1
The HF solution replenished from 2c, the pure water replenished from the pure water replenishing line 22b, the mixed solution refluxed from the stirring return line 52, and the mixed solution recovered from the collecting line 59 Mixed.

The control unit 19 is provided with a coefficient setting unit (not shown) with an LED display so as to set various conditions such as a mixing ratio of chemicals and to display the operation state of the apparatus. Has become.

Next, the mixing device 11 configured as described above
Will be described. In this embodiment, the case where the supply tank 13 has a capacity of 20 L (liter) and the mixing is performed at a ratio of HF: H ₂ O = 1: 99 will be described. At this time, the ultrasonic vortex flow meter for HF measurement 1
0.28m from 4 and ultrasonic vortex flow meter 23 for pure water measurement
It is assumed that one pulse is output per L. In that case, H
Since the mixing ratio of the F solution to the pure water is 1:99, 200 mL (corresponding to 714 pulses) of the HF solution and 19800 mL (corresponding to 70714 pulses) of the HF solution must be replenished in the supply tank 13. Must.

FIG. 2 is a diagram schematically showing an example of the liquid stirring database.

As shown in FIG.
The liquid 60 is supplied with the liquid supply capacity of the supply tank 13 and the HF liquid.
Stirring time t according to the ratio with pure water_1a~ T_1n, T_2a
~ T _2n, T_3a~ T_3n... is registered in advance
You. Therefore, the control unit 19 controls the mixed liquid of the HF liquid and the pure water.
Before starting the supply, the liquid stirring database 60
Liquid supply capacity of the supply tank 13 and the HF liquid and pure water.
Is read and set in accordance with the ratio of.

Here, control processing executed by the control unit 19 will be described.

FIGS. 3 and 4 are flowcharts for explaining the procedure of the chemical liquid mixing control process executed by the control unit 19.

As shown in FIG. 2, the control section 19 opens the HF replenishment air drive valve 15 and the pure water replenishment air drive valve 24 in step S11 (hereinafter "step" is omitted). The discharge-side flow paths of the three-way solenoid valves 18 and 27 are switched to the conduits 16c and 25c. Thus, the supply tank 13 is replenished with the 50% hydrofluoric acid stored in the HF tank 11 and the pure water generated by the pure water production device 21. At this time, the HF solution and the pure water discharged into the mixing vessel 30 from the HF replenishing pipeline 12b and the pure water replenishing pipeline 22b are mixed while rotating around the columnar member 31 in the circumferential direction. The concentration can be made uniform, and the replenishment is made into the supply tank 13 while being diffused from the plurality of small holes 30b and 30c provided in the bottom plate 30a.

In the next S12, the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for HF measurement is 714.
Check whether or not. In S12, when the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for HF measurement reaches 714, the process proceeds to S13, and the discharge side flow path of the three-way solenoid valve 18 is moved to the exhaust pipe 20 side. By switching, the HF replenishment air drive valve 15 is closed. This allows
The replenishment of the supply tank 13 with the HF solution is stopped.

If it is determined in step S12 that the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for measuring HF has not reached 714, the process proceeds to step S14. It is checked whether or not the output flow pulse count value is 70714. This S1
In 4, when the count value of the flow pulse output from the ultrasonic vortex flow meter for pure water measurement 23 has not reached 70714, the flow returns to S 12, and the flow rate output from the ultrasonic vortex flow meter 14 for HF measurement is returned. Monitor the number of pulses. As described above, the count value of the flow pulse output from the ultrasonic vortex flow meter for HF measurement 14 in S12 is monitored, and
At 14, the count value of the flow pulse output from the ultrasonic vortex flow meter 23 for measuring pure water is monitored.

In this embodiment, HF: H ₂ O = 1: 9
Since the mixing is performed at the ratio of 9, the replenishment time of the HF solution to the supply tank 13 is shorter than the replenishment time of the pure water. Therefore, the replenishment of pure water is continued even after the replenishment of the HF solution is stopped in S13.

When the count value of the flow pulse output from the ultrasonic vortex flowmeter 23 for measuring pure water reaches 70714 in S14, the process proceeds to S15, where the discharge side flow path of the three-way solenoid valve 27 is exhausted. By switching to the pipe line 28, the pure water replenishment air drive valve 24 is closed. Thus, the supply of pure water to the supply tank 13 is stopped. The supply tank 13 stores a mixed liquid mixed at a ratio of HF: H ₂ O = 1: 99.

In the next step S16, before the supply of the mixed liquid of the HF liquid and the pure water is started, the liquid supply capacity of the supply tank 13 stored in the liquid stirring database 60 and the ratio of the HF liquid to the pure water are determined. The corresponding stirring time t is read and set. Subsequently, the process proceeds to S17, where the chemical liquid supply air drive valve 35 disposed in the supply pipe 34 is closed, and the circulation air drive valve 5 disposed in the agitation return pipe 52 in S18.
3 is opened.

Subsequently, the program proceeds to S19, in which a timer is started and the chemical liquid supply pump 33 is started. Therefore, the liquid (mixed liquid) sent from the bottom of the supply tank 13 by the chemical supply pump 33 is returned to the supply tank 13 from the supply pipe 34 via the return pipe 52 for stirring.

In the next step S20, it is checked whether or not a predetermined time t (stirring time) has elapsed from the start of the timer.
The mixed liquid stored in the supply tank 13 is sucked by the chemical supply pump 33 during a predetermined time t from the start of the timer, and the mixed liquid discharged from the chemical supply pump 33 is
It is returned to the supply tank 13 through the return pipe 52 for stirring, and the concentration of the entire supply tank 13 is made uniform. On this occasion,
The liquid mixture discharged from the stirring return pipe 52 is returned to the supply tank 13 to convect the liquid mixture in the supply tank 13.

In S20, when a predetermined time t has elapsed from the start of the timer, the process proceeds to S21, and the circulation air drive valve 53 is closed. In the next step S22, the chemical liquid supply air drive valve 35 is opened, and the mixed liquid discharged by the chemical liquid supply pump 33 is supplied to the semiconductor manufacturing apparatus 45.

As described above, as the mixed liquid mixed in the supply tank 13 is supplied to the semiconductor manufacturing apparatus 45, the liquid level in the supply tank 13 gradually decreases. In the next S23, it is confirmed that there is an output signal from the second liquid level sensor 37 for detecting the lower limit position of the mixed liquid.

When there is an output signal from the second liquid level sensor 37 in S23, it is determined that the liquid level of the mixed liquid stored in the supply tank 13 has dropped to the lower limit position, and the flow proceeds to S2 shown in FIG.
Proceeding to 4, the replenishment processing of the chemical solution is performed. Note that the replenishment amount to the supply tank 13 is set to 5 L.
In this case, the supply tank 13 is replenished with 50 mL (corresponding to 178 pulses) of the HF solution, and 4950 mL (1
(Corresponding to 7678 pulses).

In S24, the discharge-side flow paths of the three-way solenoid valves 18, 27 are switched to the pipe lines 16c, 25c so that the HF replenishment air drive valve 15 and the pure water replenishment air drive valve 24 are opened. As a result, 5 stored in the HF tank 11
The 0% hydrofluoric acid and the pure water generated by the pure water producing device 21 are replenished to the supply tank 13 again.

In the next step S25, the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for HF measurement is 178.
Check whether or not. In this S25, when the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for HF measurement reaches 178, the process proceeds to S26, and the discharge side flow path of the three-way solenoid valve 18 is moved to the exhaust pipe 20 side. By switching, the HF replenishment air drive valve 15 is closed. This allows
The replenishment of the supply tank 13 with the HF solution is stopped.

If it is determined in step S25 that the count value of the flow pulse output from the HF measuring ultrasonic vortex flow meter 14 has not reached 178, the process proceeds to step S27, where the pure water measuring ultrasonic vortex flow meter 23 outputs It is checked whether or not the output flow pulse count value is 17678. This S2
In step 7, when the count value of the flow pulse output from the ultrasonic vortex flow meter 23 for pure water measurement has not reached 17978, the flow returns to step S25, and the flow rate output from the ultrasonic vortex flow meter 14 for HF measurement is returned. Monitor the number of pulses. As described above, while monitoring the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for HF measurement in S25,
At 27, the count value of the flow pulse output from the ultrasonic vortex flow meter 23 for measuring pure water is monitored.

When the count value of the flow pulse output from the ultrasonic vortex flow meter 23 for measuring pure water reaches 17678 in S27, the process proceeds to S28, and the discharge side flow path of the three-way solenoid valve 27 is exhausted. By switching to the pipe line 28, the pure water replenishment air drive valve 24 is closed. Thus, the supply of pure water to the supply tank 13 is stopped. The supply tank 13 stores the replenished mixture at a ratio of HF: H ₂ O = 1: 99.

Thereafter, the process returns to S23, and the chemical solution replenishment process from S23 is repeated.

The ratio of the mixed liquid and the count value of the flow rate pulse of each chemical are merely examples, and it goes without saying that they can be set arbitrarily.

As described above, since the pure water and the HF solution replenished to the supply tank 13 are circulated through the return line for stirring 52 before being supplied to the semiconductor manufacturing apparatus 45, the ratio becomes constant. Also in the supply tank 13, the concentration of the mixed solution of the pure water and the HF solution can be eliminated, and the concentration of the entire mixed solution can be kept uniform.

FIG. 5 is a block diagram for explaining a configuration of a modification of the present invention. In FIG. 5, the same parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, the return pipe 52 for stirring is provided so as to communicate between the supply pipe 34 and the recovery pipe 59. Therefore, when the agitation return line 52 disposed in the agitation return line 52 is opened and the chemical supply pump 33 is activated, the liquid (mixed liquid) sent from the bottom of the supply tank 13 Is returned to the upper part of the supply tank 13 via the supply pipe 34, the return pipe 52 for stirring, and the recovery pipe 59.

One end of the supply pipe 34 branches into a plurality of connection pipes 62, and is connected to a plurality of locations on the bottom of the supply tank 13 via the plurality of connection pipes 62. Therefore, the liquid staying at the bottom of the supply tank 13 can be efficiently sucked and returned to the upper part of the supply tank 13, and the entire liquid in the supply tank 13 can be circulated in a short time.

The end of the recovery pipe 59 may also be connected to the plurality of connection pipes 62 so as to return to a plurality of locations in the supply tank 13.

In this embodiment, the case where hydrofluoric acid and pure water are mixed at a predetermined ratio has been described as an example. However, the present invention can be applied to the case where other chemicals are mixed. Of course.

In this embodiment, the case of mixing two kinds of liquids of hydrofluoric acid and pure water has been described as an example. However, the present invention is also applicable to the case of mixing two or more kinds of liquids having different components. Of course, the invention can be applied.

[0057]

As described above, according to the first aspect of the present invention, the stirring means for continuously stirring the liquid in the supply tank for a predetermined time, and the mixed liquid for supplying the mixed liquid mixed in the supply tank downstream. Since a discharge valve provided in the discharge path and valve control means for opening the discharge valve after a predetermined time has elapsed after the stirring by the stirring means is started, the mixed liquid mixed in the supply tank is shortened. Can be sufficiently stirred in time,
It is possible to stably supply a uniformly mixed liquid without concentration unevenness of the mixed liquid mixed in the supply tank.

According to the second aspect of the present invention, the liquid supplied to the supply tank is supplied to a circulation path having one end connected near the bottom of the supply tank and the other end connected to another portion of the supply tank. A pump for circulating was provided, the pump was started when a predetermined amount or more of liquid from each replenishment line was supplied to the supply tank, and after a lapse of a predetermined time, the circulation of the liquid by the pump was stopped. The liquid can be sufficiently stirred while being circulated. Further, according to the present invention, a discharge valve provided in a mixed liquid discharge path for supplying the mixed liquid mixed in the supply tank downstream,
A valve control means for opening the discharge valve after a predetermined time has elapsed from the start of the stirring by the pump, so that the liquid mixed in the supply tank can be uniformly supplied without concentration unevenness. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a mixing apparatus according to the present invention.

FIG. 2 is a diagram schematically illustrating an example of a liquid stirring database.

FIG. 3 is a flowchart illustrating a procedure of a chemical mixture control process executed by a control unit 19;

FIG. 4 is a flowchart illustrating a procedure of a chemical liquid mixing control process performed after the process illustrated in FIG. 3;

FIG. 5 is a block diagram for explaining a schematic configuration of a modification of the mixing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mixing apparatus 11 HF tank 12 HF supply path 13 Supply tank 14 Ultrasonic vortex flowmeter for HF measurement 15 Air drive valve for HF supply 19 Control unit 21 Pure water production apparatus 22 Pure water supply path 23 Ultrasonic vortex for pure water measurement Flow meter 24 Air drive valve for supplying pure water 33 Chemical supply pump 34 Supply conduit 36 First liquid level sensor 37 Second liquid level sensor 35 Air drive valve for supplying chemical liquid 45 Semiconductor manufacturing apparatus 52 Return conduit for stirring 59 Recovery pipe Route 60 Liquid stirring database 62 Connection pipeline

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 21/306 H01L 21/306 J F term (Reference) 4G035 AB37 AB38 AC29 AC31 AE03 AE13 4G037 AA12 BA01 BB01 BC02 BD04 BE02 EA01 EA02 5F043 AA01 AA40 BB30 DD30 EE05 EE23 EE24 EE29 EE31 EE33

Claims (2)

[Claims] 1. A plurality of replenishment lines provided for each liquid having different components and having a metering means and a valve means for replenishing the liquid to a supply tank, and mixing the liquids at a predetermined ratio in the supply tank. A control means for controlling each of the valve means based on a signal from the measuring means in order to replenish a predetermined amount of liquid from each of the replenishment lines. Stirring means, a discharge valve provided in a mixed liquid discharge path for supplying the mixed liquid mixed in the supply tank downstream, and opening the discharge valve after a lapse of a predetermined time from the start of stirring by the stirring means. A mixing device, comprising: valve control means for performing a valve. 2. A plurality of replenishment lines provided for each liquid having different components and having a measuring means and a valve means for replenishing the liquid to the supply tank, and mixing the liquids in the supply tank at a predetermined ratio. A control means for controlling each of the valve means based on a signal from the measuring means so as to replenish a predetermined amount of liquid from each of the replenishment lines, one end of which is near the bottom of the supply tank. A circulation path, the other end of which is connected to the other part of the supply tank; a pump provided in the circulation path, for circulating the liquid supplied to the supply tank; Pump control for starting the pump when a predetermined amount or more of liquid is supplied from the line, and controlling the pump so as to stop circulation of the liquid by the pump after a predetermined time has elapsed. Means, a discharge valve provided in a mixed liquid discharge path for supplying the mixed liquid mixed in the supply tank downstream, and opening the discharge valve after a lapse of a predetermined time from the start of circulation by the pump. A mixing device, comprising: valve control means.