JP2001038187A - Mixer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the concn. change of a liq. mixture caused by the number of times of liq. replenishment at the time of supplying and mixing two liqs. different in composition in a tank. SOLUTION: This mixer 10 is constituted so that 50% hydrofluoric acid stored in an HF tank 11 and pure water generated by a pure water producer 21 are supplied to a feed tank 13 and mixed in a specified ratio, and then the obtained liq. mixture is supplied to a semiconductor producer 45 set on the downstream side of the tank 13. Since the treatment for mixing liqs. in a specified ratio in the feed tank 13 is carried out at a specified number of times, e.g. ten, thereafter the liqs. are weighed by the accumulated error for the specified number of times in the succeeding (e.g. eleventh) mixing, a control part 19 can correct the error accumulated for the specified number of times at every time the treatment is carried out the specified times even though minute errors due to the delayed response of a valve controlling the supply of chemicals are accumulated.

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 mixing a plurality of chemicals to supply a mixed liquid used in a flat panel display manufacturing process such as a semiconductor or liquid crystal.

[0002]

2. Description of the Related Art Conventionally, in a mixing apparatus for mixing chemical solutions having different components, a constant amount of a stock solution of a chemical solution is measured in respective measuring tanks, and then the measured chemical solutions are dropped into a mixing tank and mixed. Dilute to the required concentration with water. Thereafter, the mixed / diluted chemical solution (mixed solution) is dropped into the storage tank, and the heated or cooled chemical solution (mixed solution) is supplied to the semiconductor manufacturing apparatus.

In a conventional mixing apparatus, the measurement of a chemical solution and the amount of dilution with pure water are controlled by the height of the liquid level in each tank. Further, when changing the mixing ratio of the chemical liquid, the position of a liquid level detecting means such as an optical liquid level sensor is manually moved and adjusted. In addition, in the conventional mixing apparatus, a constant-quantity infusion pump is used to replenish the undiluted chemical solution, and the replenishment amount is controlled by the number of times the chemical solution is discharged (the number of times the plunger and the diaphragm of the pump are pushed out). There is also. For example, if the amount of one discharge is 10 mL, four discharges may be performed to replenish 40 mL of the stock solution.

[0004]

However, in the conventional mixing apparatus having the above-mentioned structure, for example, after measuring a chemical in a weighing tank, the chemical is transferred to a preparation tank, diluted with pure water, and then stored in a storage tank. Since a three-stage process of transferring the liquid to the heater and adjusting the liquid temperature by a heater or the like is required, the number of components increases, and the apparatus becomes large.

In addition, since a liquid level sensor is used for weighing pure water used for weighing and diluting a chemical solution and for detecting a request for replenishing the chemical solution to the storage tank, the liquid foams or rises in the tank. If it is wavy, there is a problem that the sensor malfunctions and it becomes impossible to mix the chemical solution with a mixing ratio of a predetermined accuracy. In order to solve such a problem, it has been considered to measure the replenishment amount of each chemical solution with a flow meter and control the replenishment amount of each chemical solution based on an output signal from the flow meter. However, when the replenishment amount of the chemical is measured by the flow meter and the replenishment amount of the chemical is controlled so that the concentration of the mixed solution becomes a predetermined value, the following problem may occur.

That is, in an apparatus configured to control the replenishment amount of a chemical solution using a flow meter, the valve of the chemical solution supply path is opened when the integrated value of the flow pulse output from the flow meter reaches a target value. Even when the valve is closed, a minute chemical solution having an error is supplied during the valve closing operation. Therefore, the error amount of the chemical solution due to the valve closing operation is accumulated every time the liquid replenishment process is performed, and the concentration of the mixed solution is gradually changed and set as the number of times of the liquid replenishment process increases. There is a problem that the density deviates from the target density.

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

[0008]

In order to solve the above problems, the present invention has the following features. According to the present invention, a plurality of replenishment lines provided for each of liquids 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 Control means for controlling 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,
The control means is characterized in that one of the liquid replenishment processes for replenishing the supply tank with a predetermined amount of each liquid for a predetermined number of times corrects an accumulated error.

Therefore, according to the present invention, one of the liquid replenishment processes for replenishing the supply tank with a predetermined amount of each of the liquids a predetermined number of times corrects the accumulated error. Each time the liquid mixing process is performed a predetermined number of times, the cumulative error can be corrected a predetermined number of times even if a minute error due to a response delay of the valve that controls the valve is accumulated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of the mixing apparatus according to the present invention. As shown in FIG. 1, the mixing device 10 replenishes the supply tank 13 with the 50% hydrofluoric acid stored in the HF tank 11 and the pure water generated by the pure water production device 21, and supplies the water to the predetermined tank. The mixture is mixed at a ratio, and the mixed liquid mixed in the supply tank 13 is supplied to the semiconductor manufacturing apparatus 45 installed on the downstream side of the supply tank 13. In addition, hydrofluoric acid is hydrogen fluoride (hy
drogen fluoride), and is referred to as "HF solution" below.

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). Reference numeral 14 denotes an ultrasonic vortex flow meter for measuring HF, which measures the flow rate of the HF liquid sent through the HF replenishment path 12. Also, H
The liquid contact part of the ultrasonic vortex flowmeter 14 for F measurement is formed of the above-mentioned PFA.

An HF replenishment air drive valve 15 having a flow rate adjusting mechanism is provided downstream of the HF measuring ultrasonic vortex flow meter 14. The compressed air for driving the HF replenishment air drive valve 15 is supplied to the air supply passage 16 by about 0.5 to 0.7 MPa.
a at a pressure in the range a, and 0.3MPa by the pressure reducing valve 17.
The pressure is reduced to a. The compressed air supplied from the air supply path 16 is supplied to the HF by the switching operation of the three-way solenoid valve 18.
The air is supplied to the supplementary air drive valve 15.

The control unit 19 is connected to the ultrasonic vortex flow meter 14 for HF measurement and the three-way solenoid valve 18 and counts the number of flow pulses output from the ultrasonic vortex flow meter 14 for HF measurement. 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. Also, the discharge side flow path of the three-way solenoid valve 18 is
When switched to the c side, the HF replenishment air drive valve 15 opens, and when the discharge side flow path of the three-way solenoid valve 18 is switched to the exhaust path 20 side, the HF replenishment air drive valve 15 closes.
The HF replenishment air drive valve 15 is connected to the supply tank 13 via the HF replenishment pipe 12c.

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 the pressure is reduced to 0.1 by the pressure reducing valve 26.
The pressure is reduced to 3 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. 3 way solenoid valve 2 according to
The control for switching the discharge side flow path 7 to the exhaust path 28 side or the pipe line 25c side is performed.

When the discharge side flow path of the three-way solenoid valve 27 is switched to the pipe 25c side, the pure water replenishment air drive valve 24
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 the pure water replenishment pipeline 22c.

In the supply tank 13, the HF liquid is replenished by opening the HF replenishing air drive valve 15, and the 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. Further, first and second liquid level sensors 36 and 37 for monitoring the liquid level of the mixed liquid are inserted into the supply tank 13. 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 34. Also,
On the downstream side of the chemical supply pump 33, a chemical supply air drive valve 35 with a flow rate adjusting mechanism is provided. Further, a return line 52 for stirring is branched from a pipe 34 between the chemical supply pump 33 and the air supply valve 35 for chemical supply, and a part of the mixed liquid (chemical) discharged from the chemical supply pump 33. Reflux to the supply tank 13
The mixed solution inside is stirred to make the concentration uniform.

The supply tank 13 and the semiconductor manufacturing apparatus 4
A recovery conduit 60 for returning excess mixed liquid in the semiconductor manufacturing apparatus 45 to the supply tank 13 is communicated with the supply pipe 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 22c, the mixed solution refluxed from the stirring return line 52, and the mixed solution recovered from the recovery line 60 Mixed.

The control unit 19 is provided with a coefficient setting device (not shown) with an LED display so as to set various conditions such as a mixing ratio of a chemical solution and to display an operation state of the apparatus. Has become. Next, the mixing device 11 configured as described above
Will be described. In the present embodiment, the case where the capacity of the supply tank 13 is 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.

FIGS. 2 to 4 are flowcharts for explaining the procedure of the chemical mixture control process executed by the control unit 19. As shown in FIG. 2, the control unit 19 controls the three-way solenoid valve to open the HF replenishment air drive valve 15 and the pure water replenishment air drive valve 24 in step S11 (hereinafter “step” is omitted). Lines 18 and 27 on the discharge side
Switch to 6c, 25c side. Thereby, the HF tank 1
50% hydrofluoric acid stored in 1 and pure water production device 2
The pure water generated by 1 is supplied to the supply tank 13.

In the next step S12, the count value of the flow pulse output from the ultrasonic vortex flow meter for HF measurement 14 becomes 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 HF measuring ultrasonic vortex flow meter 14 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. In S14, when the count value of the flow pulse output from the ultrasonic vortex flowmeter 23 for measuring pure water reaches 70714, the process proceeds to S15, where the discharge side flow path of the three-way solenoid valve 27 is connected to the exhaust pipe 28. Side, and 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.

Subsequently, the program proceeds to S16, in which a timer is started and the chemical liquid supply pump 33 is started. In the next step S17, it is checked whether five minutes have elapsed since the start of the timer. During a lapse of 5 minutes from the start of the timer, the entire amount of the mixed liquid stored in the supply tank 13 is sucked by the chemical supply pump 33, and the mixed liquid discharged from the chemical supply pump 33 is returned via the return line 52 for stirring. It is returned to the supply tank 13 to make the concentration of the entire supply tank 13 uniform.

In S17, five minutes after the start of the timer, 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. Thereby, 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 S19, a second detection of the lower limit position of the mixed liquid is performed.
Confirm that there is an output signal from the liquid level sensor 37.

If there is an output signal from the second liquid level sensor 37 in S19, 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 process proceeds to S2 shown in FIG.
The process proceeds to 0, and a replenishment process of the chemical solution is performed. It is assumed 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 HF solution, and 4950 mL (17
(Corresponding to 678 pulses).

In S20, it is checked whether or not the number of times of the liquid replenishment operation is the tenth. In this S20, if the number of times of the chemical solution replenishment operation is less than the tenth, the process proceeds to S21 and the HF
The discharge-side flow paths of the three-way solenoid valves 18 and 27 are switched to the pipe lines 16c and 25c so that the replenishment air drive valve 15 and the pure water replenishment air drive valve 24 are opened. Thereby, the 50% hydrofluoric acid stored in the HF tank 11 and the pure water generated by the pure water production device 21 are refilled into the supply tank 13 again.

In the next step S22, the count value of the flow pulse output from the HF measuring ultrasonic vortex flow meter 14 is 178.
Check whether or not. In S22, 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 S23, 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 S22 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 S24, in which 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 4, when the count value of the flow pulse output from the ultrasonic vortex flow meter for pure water measurement 23 does not reach 17978, the flow returns to S22, 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 for HF measurement 14 in S22,
At 24, the count value of the flow pulse output from the ultrasonic vortex flowmeter 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 S24, the process proceeds to S25, 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.

In the next step S26, the count value of the replenishment number counter is added once, and the process returns to the step S19 to repeat the chemical liquid replenishment process from the step S19. Then, when the count value of the replenishment counter reaches ten times, the flow shifts from S20 to S27 shown in FIG. In S27, the discharge-side flow paths of the three-way solenoid valves 18, 27 are switched to the conduits 16c, 25c so that the HF replenishment air drive valve 15 and the pure water replenishment air drive valve 24 are opened. Thereby, the 50% hydrofluoric acid stored in the HF tank 11 and the pure water generated by the pure water production device 21 are refilled into the supply tank 13 again.

In the next S28, the count value of the flow pulse output from the HF measuring ultrasonic vortex flow meter 14 is 158.
Check whether or not. The count value 158 of the flow rate pulse in S28 is as follows: when the above-mentioned chemical solution replenishment process is performed ten times, the injection error for ten times is considered to be about 10% of one chemical solution replenishment amount (count value 178).
In the eleventh chemical solution replenishment process, this is a value calculated so that the injection is performed with the amount reduced to about 90% of the normal chemical solution replenishment amount. As a result, the injection error of 10 injections of the HF solution is 1
It is offset by the first chemical replenishment process.

Then, in S28, when the count value of the flow pulse output from the ultrasonic vortex flow meter 14 for HF measurement has reached 158, the process proceeds to S29, where the three-way solenoid valve 1
The HF replenishment air drive valve 15 is closed by switching the discharge side flow path 8 to the exhaust pipe 20 side. As a result, the replenishment of the supply tank 13 with the HF solution is stopped, and the injection error for 10 injections is corrected.

For example, the injection error generated in one chemical replenishment process due to the delay of the opening / closing operation of the HF replenishment air drive valve 15 and the pure water replenishment air drive valve 24 as described above is so small that it cannot be measured. In the case, a predetermined number of times (for example, 10 times)
After performing the chemical solution replenishment process, the accumulated error for a predetermined number of times can be offset to suppress a change in the concentration of the mixed solution stored in the supply tank 13.

If it is determined in step S28 that the count value of the flow pulse output from the HF measuring ultrasonic vortex flow meter 14 has not reached 158, the flow advances to step S30. It is checked whether or not the output flow pulse count value is 17678. This S3
At 0, when the count value of the flow pulse output from the ultrasonic vortex flowmeter for pure water measurement 23 does not reach 17678, the flow returns to S28, and the flow rate output from the ultrasonic vortex flowmeter 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 for HF measurement 14 in S28,
At 30, the count value of the flow pulse output from the ultrasonic vortex flowmeter 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 S30, the process proceeds to S32, in which 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.

In the next step S32, the count value of the replenishment counter is cleared to zero. Thereafter, the process returns to S19, and the chemical solution replenishment process from S19 is repeated. FIG. 5 is a graph showing a change in density when a conventional injection error is not corrected. FIG. 6 is a graph showing a change in density when an injection error is corrected every predetermined number of times as in the present invention.

When the mixing apparatus having the above-described configuration continuously performs the mixing processing operation having a plus error of the chemical liquid, as shown in the measured data of the concentration of the mixed chemical liquid (graph I) in FIG. The drug solution concentration may increase. This is because a response delay occurs between the time when the output pulse from the HF measuring ultrasonic vortex flow meter 14 reaches the set value of the chemical solution replenishment amount and the time when the HF replenishment air drive valve 15 is completely closed, This is a case where the delay is accumulated as a plus error. In other words, when the replenishment of the HF solution is taken as an example, the place where 50 mL of the HF solution should be originally replenished into the supply tank 3 (178 counts with the output pulse from the ultrasonic vortex flowmeter 14 for HF measurement) indicates that the supply tank 3 should be refilled. When the output pulse from the sonic vortex flow meter 14 reaches 178 counts, the HF replenishment air drive valve 15 starts closing.

Therefore, actually, when the output pulse from the ultrasonic vortex flow meter 14 for HF measurement has passed 1 to 3 pulses, the HF replenishment air drive valve 15 is completely closed. Therefore, the set value is 0.2 to 0.8.
The HF solution is replenished to the supply tank 13 by about mL. The excess amount is accumulated as an error each time the replenishment operation is repeated, so that the chemical concentration of the mixed liquid mixed in the supply tank 13 gradually increases. Since the replenishment amount of the HF solution at one time is as small as 50 mL, the replenishment flow rate of the HF solution is also very small. Therefore, the amount of one overshoot accompanying the closing operation of the air drive valve 15 for refilling HF is 0.2 to 0.
It is a very small amount of about 8 mL.

Therefore, it is extremely difficult to correct the overshoot every time the HF solution is replenished. Therefore, in the mixing device 10 of the present invention, after performing the chemical replenishment process on the supply tank 13 ten times, the HF is replenished by subtracting the accumulated error of the ten times during the eleventh replenishment. The change in the concentration of the mixed liquid in the supply tank 13 is suppressed by canceling the accumulated error of the liquid.

As a result, the mixing device 10 sets the concentration of the mixed solution supplied to the semiconductor manufacturing device 45 to a preset set value (target concentration) as shown in the measured concentration data of the mixed chemical solution (Graph II) in FIG. Value), the mixture can be stably supplied at a set concentration. In the present 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 of course be applied to the case where other chemicals are mixed. .

In this embodiment, the case where two kinds of liquids of hydrofluoric acid and pure water are mixed is described as an example. However, the case where two or more kinds of liquids having different components are mixed is also described. Of course, the invention can be applied. Further, in the present embodiment, the case has been described in which the cumulative error for ten times is subtracted at the time of the eleventh replenishment of the drug solution to offset the cumulative error, but the present invention is not limited to this. The cumulative error can be offset by correcting the chemical replenishment amount once for a predetermined number of times according to the above, so that, for example, the cumulative error for five times may be subtracted at the time of the sixth chemical replenishment, or may be reduced to fifteen times. Can be reduced at the time of the 16th replenishment of the drug solution.

In the present embodiment, the cumulative plus error due to the predetermined number of replenishments of the chemical is corrected by one minus replenishment. However, the present invention is not limited to this. The accumulated minus error may be corrected by one plus supplement. In addition, the cumulative plus error due to the predetermined number of replenishments may be negative while repeating the correction of the cumulative plus error due to the replenishment of the predetermined number of times by one minus replenishment. The correction may be regarded as one cycle, for example, after performing two cycles, the minus replenishment in the next one cycle may not be performed.

[0045]

As described above, according to the present invention, the liquid replenishment processing for replenishing the supply tank with a predetermined amount of each liquid is performed a predetermined number of times, so that one liquid replenishment processing corrects the accumulated error. Even if a small error is accumulated due to a response delay of the valve for controlling the supply of the chemical solution, the accumulated error of a predetermined number of times can be corrected every time the liquid mixing process is performed a predetermined number of times. Therefore, even if there is a small error that cannot be measured with a flow meter,
When the cumulative error of a predetermined number of times reaches a measurable amount, the next measurement value can be changed so as to cancel the cumulative error, and the concentration of the mixed solution can be adjusted to be within the predetermined range of the target value become. This makes it possible to stably supply the liquid mixture having a predetermined concentration to a downstream device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a mixing device according to the present invention.

FIG. 2 is a flowchart for explaining a procedure of a chemical mixture control process executed by a control unit 19;

FIG. 3 is a flowchart illustrating a procedure of a chemical liquid mixing control process executed after the process illustrated in FIG. 2;

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 graph showing a change in density when a conventional injection error is not corrected.

FIG. 6 is a graph showing a density change when an injection error is corrected every predetermined number of times as in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mixing apparatus 11 HF tank 12 HF supply path 13 Supply tank 14 Ultrasonic vortex flow meter for HF measurement 15 Air drive valve for HF supply 18, 27 Three-way solenoid valve 19 Control unit 21 Pure water production apparatus 22 Pure water supply path 23 Ultrasonic vortex flow meter for water measurement 24 Air drive valve for supplying pure water 33 Chemical supply pump 34 Supply line 36 First liquid level sensor 37 Second liquid level sensor 35 Air drive valve for supplying chemical liquid 45 Semiconductor manufacturing equipment 52 Stirring Return line 60 Recovery line

Claims (1)

[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 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. A mixing apparatus characterized in that one liquid replenishment process of replenishing a predetermined amount of each liquid for a predetermined number of times corrects an accumulated error.