JP2020198357A - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

To provide a substrate processing apparatus and a substrate processing method for producing a drug solution whose concentration is stabilized with high accuracy.SOLUTION: A dilution solution is supplied by a supply pipe 50, and a chemical solution is supplied by a supply pipe 40. The flow rate of the dilution solution flowing through the supply pipe 50 is adjusted by an adjustment unit 53. In a mixing tank 230, the dilution solution supplied by the supply pipe 50 and a chemical solution supplied by the supply pipe 40 are mixed. The concentration of the chemical solution in the mixture of the dilution solution and the chemical solution is measured by a concentration meter 94. A control unit 310 determines the correction amount of the flow rate of the dilution solution such that the concentration measured by the concentration meter 94 becomes a set value, and the determined correction amount is given to the adjustment unit 53. The flow rate of the dilution solution flowing through the supply pipe 50 is corrected by the adjustment unit 53 on the basis of the given correction amount.SELECTED DRAWING: Figure 3

Description

The present invention relates to a substrate processing apparatus and a substrate processing method for processing a substrate using a diluted chemical solution.

A substrate processing device is used to process a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display device, a glass substrate for a photomask, or a glass substrate for an optical disk using a processing liquid. In a substrate processing apparatus that performs substrate processing such as etching of a substrate, a diluted chemical solution is generated as a processing solution to be supplied to the substrate.

For example, in the substrate processing apparatus described in Patent Document 1, the undiluted solution of hydrofluoric acid stored in the hydrofluoric acid tank is supplied to the mixing section through the hydrofluoric acid supply pipe. Further, DIW (De-ionized water) is supplied to the mixing section through the DIW supply pipe. By appropriately adjusting the flow rate of the undiluted solution of hydrofluoric acid passing through the hydrofluoric acid supply pipe by the flow rate adjusting valve, dilute hydrofluoric acid having a desired concentration is produced in the mixing portion.

Japanese Patent No. 5043487

In recent years, with the miniaturization of semiconductors, in order to improve the accuracy of etching, it is required to stabilize the concentration of the chemical solution used for etching with high accuracy. For example, it is required to stabilize the concentration of dilute hydrofluoric acid with an accuracy of 5000 ± 5 ppm. However, as a result of the studies by the present inventors, when DIW supplied from factory equipment is used, the method described in Patent Document 1 cannot produce dilute hydrofluoric acid whose concentration is stabilized with the above accuracy. It turned out to be difficult.

Therefore, it is conceivable to provide a weighing tank in which DIW is stored in the substrate processing apparatus and supply DIW from the weighing tank. In this case, it is necessary to provide an extremely large weighing tank. For example, when a stock solution of hydrofluoric acid having a concentration of 49% is stored in a 2.4 L hydrofluoric acid tank, about 240 L of DIW is required to generate dilute hydrofluoric acid having a concentration of about 1/100 (5000 ppm). It is necessary to provide a weighing tank in which is stored. However, it is not realistic to provide such a large weighing tank in the substrate processing apparatus.

Further, in the single-wafer type substrate processing apparatus, since a plurality of processing units simultaneously process a plurality of substrates, a large amount of chemical solution is consumed all at once. Therefore, it is not preferable to reduce the size of the weighing tank for DIW by reducing the capacity of the hydrofluoric acid tank.

An object of the present invention is to provide a substrate processing apparatus and a substrate processing method for producing a chemical solution whose concentration is stabilized with high accuracy.

As a result of repeating various experiments and discussions, the present inventors have found that fluctuations in the pressure of the dilution solution supplied from the factory equipment affect the stability of the concentration of the chemical solution generated. .. Due to the fluctuation of the pressure of the dilution liquid, the flow rate of the dilution liquid fluctuates in a relatively long cycle. Such fluctuations in the pressure of the diluent from the factory equipment cannot be predicted by the user and cannot be controlled. In consideration of these circumstances, the present inventors have found a configuration capable of stabilizing the concentration of the drug solution with high accuracy, and have arrived at the following invention.

(1) The substrate processing apparatus according to the present invention is a substrate processing apparatus that processes a substrate using a diluted chemical solution, and is a first pipe for supplying a diluting solution and a second pipe for supplying the chemical solution. A mixture of the piping, the first adjusting unit that adjusts the flow rate of the diluting liquid flowing through the first pipe, and the dilution liquid supplied by the first pipe and the chemical liquid supplied by the second pipe. Determine the correction amount of the flow rate of the dilution solution so that the concentration measured by the tank, the concentration meter of the dilution solution and the drug solution, and the concentration measured by the concentration meter becomes the set value. It is provided with a control unit that gives a determined correction amount to the first adjustment unit, and the first adjustment unit corrects the flow rate of the diluting liquid flowing through the first pipe based on the correction amount given by the control unit. To do.

In this substrate processing apparatus, the dilution liquid is supplied by the first pipe, and the chemical liquid is supplied by the second pipe. The flow rate of the diluting liquid flowing through the first pipe is adjusted by the first adjusting unit. In the mixing tank, the dilution solution supplied by the first pipe and the chemical solution supplied by the second pipe are mixed. The concentration of the chemical solution in the mixed solution of the dilution solution and the chemical solution is measured by a densitometer. The correction amount of the flow rate of the diluting liquid is determined so that the concentration measured by the densitometer becomes a set value, and the determined correction amount is given to the first adjusting unit.

According to this configuration, even if the flow rate of the diluent liquid fluctuates due to the fluctuation of the pressure of the dilution liquid, the correction amount determined so that the concentration measured by the densitometer becomes the set value. Based on this, the flow rate of the diluting liquid flowing through the first pipe is corrected by the first adjusting unit. As a result, in the mixing tank, it is possible to generate a chemical solution having a stabilized concentration as a mixed solution with high accuracy.

(2) The substrate processing apparatus may further include a chemical solution tank for storing the chemical solution, and the second pipe may be connected to the chemical solution tank to supply the chemical solution stored in the chemical solution tank to the mixing tank. In this case, since the chemical solution is supplied from the chemical solution tank to the mixing tank through the second pipe, fluctuations in the pressure of the chemical solution flowing through the second pipe are suppressed. As a result, the flow rate of the chemical solution flowing through the second pipe can be easily stabilized. As a result, it is possible to more easily produce a drug solution whose concentration is stabilized with high accuracy.

(3) The chemical solution tank includes a first chemical solution tank and a second chemical solution tank, and the chemical solution stored in the first chemical solution tank and the chemical solution stored in the second chemical solution tank are the second chemical solution. It may be alternately supplied to the mixing tank by piping. In this case, the chemical solution can be supplied to the mixing tank without delaying the processing of the substrate.

(4) The substrate processing apparatus may further include a third pipe that guides the diluting liquid supplied by the first pipe and the chemical liquid supplied by the second pipe to the mixing tank while mixing them. In this case, the mixed liquid can be efficiently generated in the third pipe.

(5) The substrate processing device is provided so as to branch off from the third pipe, and guides the mixed liquid of the diluting liquid supplied by the first pipe and the chemical liquid supplied by the second pipe to the mixing tank. A fourth pipe may be further provided for discharging without any trouble. In this case, when the flow rate of the diluting solution or the chemical solution is not stable, the mixed solution generated in the third pipe can be discharged without leading to the mixing tank. As a result, it is possible to generate a chemical solution having a stabilized concentration with higher accuracy in the mixing tank.

(6) The first adjusting unit may be an electric pressure regulating regulator. According to this configuration, the flow rate of the diluting liquid can be easily adjusted even when the flow rate of the diluting liquid flowing through the first pipe is relatively large.

(7) The substrate processing apparatus may further include a second adjusting unit for adjusting the flow rate of the chemical solution flowing through the second pipe. According to this configuration, the flow rate of the chemical solution flowing through the second pipe can be easily stabilized. As a result, it is possible to more easily produce a drug solution whose concentration is stabilized with high accuracy.

(8) The second adjusting unit may be a motor needle valve. According to this configuration, the flow rate of the chemical solution can be easily adjusted even when the flow rate of the chemical solution flowing through the third pipe is relatively small.

(9) The inner diameter of the first pipe may be larger than the inner diameter of the second pipe. In this case, the dilution solution can be easily supplied at a relatively large flow rate and the chemical solution can be easily supplied at a relatively small flow rate.

(10) When the first threshold range is set for the concentration of the chemical solution and the concentration measured by the densitometer is outside the first threshold range, the control unit determines the flow rate of the dilution solution. The correction amount may be determined. In this case, it is possible to generate a drug solution whose concentration is stabilized with high accuracy by simple control.

(11) When a second threshold range including the first threshold range is set for the concentration of the drug solution and the concentration measured by the densitometer is outside the second threshold range. The supply of the dilution solution through the first pipe and the supply of the chemical solution through the second pipe may be stopped. In this case, it is possible to suppress the production of a chemical solution whose concentration is not stable.

(12) The first pipe may be connected to a facility for supplying a dilution liquid in a factory where a substrate processing apparatus is installed. In this case, a large amount of dilution liquid can be supplied without increasing the size of the substrate processing apparatus. Further, even when the pressure of the diluting solution supplied from the factory equipment fluctuates, it is possible to generate a chemical solution having a stabilized concentration with high accuracy.

(13) The substrate processing apparatus further includes a substrate processing unit for processing the substrate and a fifth pipe for supplying the mixed solution stored in the mixing tank to the substrate processing unit, and the densitometer flows through the fifth pipe. It may be provided so as to measure the concentration of the chemical solution in the mixed solution. In this case, since the densitometer is provided in the fifth pipe that supplies the mixed solution to the substrate processing unit, the concentration of the chemical solution used for the substrate processing can be measured more accurately.

(14) The substrate processing method according to the second invention is a substrate processing method in which a substrate is treated with a diluted chemical solution, and is a step of supplying a dilution solution through a first pipe and a second. The step of supplying the chemical solution by the pipe, the step of adjusting the flow rate of the dilution liquid flowing through the first pipe by the adjusting unit, and the step of supplying the dilution liquid supplied by the first pipe and the second pipe in the mixing tank. A step of mixing the prepared chemical solution, a step of measuring the concentration of the chemical solution in the mixed solution of the dilution solution and the chemical solution with a densitometer, and a step of measuring the concentration measured by the densitometer with a densitometer. The step of adjusting the flow rate of the diluting liquid by the adjusting unit includes the step of determining the correction amount of the flow rate of No. 1 and giving the determined correction amount to the adjusting unit. This includes correcting the flow rate of the diluting liquid flowing through the above by the adjusting unit.

According to this configuration, even when the flow rate of the diluting solution fluctuates due to the fluctuation of the pressure of the diluting solution, a chemical solution having a stabilized concentration is produced as a mixed solution in the mixing tank. be able to.

(15) A threshold range is set for the concentration of the chemical solution, and the correction amount is determined when the concentration measured by the densitometer is out of the threshold range for a predetermined time or longer. It may include determining the amount. In this case, it is possible to generate a drug solution whose concentration is stabilized with high accuracy by simple control.

According to the present invention, a drug solution having a stabilized concentration can be produced with high accuracy.

It is a figure which shows the structure of the substrate processing apparatus which concerns on one Embodiment of this invention. It is a side view which shows the internal structure of the processing chamber of FIG. It is a figure which shows the structure of the chemical liquid generation part of FIG. It is a figure which shows the structure of the control part. It is a flowchart which shows the algorithm of the chemical solution replenishment processing performed by the chemical solution replenishment program. It is a flowchart which shows the algorithm of the chemical solution replenishment processing performed by the chemical solution replenishment program.

(1) Configuration of Substrate Processing Device The substrate processing device according to the embodiment of the present invention will be described below with reference to the drawings. In the following description, the substrate refers to a semiconductor substrate, a liquid crystal display device, an FPD (Flat Panel Display) substrate such as an organic EL (Electro Luminescence) display device, an optical disk substrate, a magnetic disk substrate, a magneto-optical disk substrate, and the like. Refers to a photomask substrate, a ceramic substrate, a solar cell substrate, or the like.

FIG. 1 is a diagram showing a configuration of a substrate processing apparatus according to an embodiment of the present invention. In FIG. 1 and FIG. 2 described later, arrows indicating the X, Y, and Z directions orthogonal to each other are attached to clarify the positional relationship. The X and Y directions are orthogonal to each other in the horizontal plane, and the Z direction corresponds to the vertical direction. As shown in FIG. 1, the substrate processing apparatus 300 includes a substrate processing unit 100, a chemical solution generation unit 200, and a control unit 310, and is installed in, for example, a factory. FIG. 1 mainly shows a schematic plan view of the substrate processing unit 100.

In the factory where the substrate processing apparatus 300 is installed, the chemical solution supply source 301, the dilution solution supply source 302, and the nitrogen gas supply sources 303 and 304 are provided as factory equipment (factory power). The chemical solution supply source 301 supplies a stock solution of the chemical solution (hereinafter, referred to as a drug substance solution). In this example, the drug substance solution is hydrofluoric acid with a concentration of 49%. The dilution solution supply source 302 supplies a dilution solution for diluting the drug solution. In this example, the diluting solution is DIW (De-ionized water). The nitrogen gas supply sources 303 and 304 supply nitrogen gas. The nitrogen gas supply sources 303 and 304 may be the same nitrogen gas supply source.

The chemical solution generation unit 200 generates a diluted chemical solution in which the drug substance solution is diluted by using the above-mentioned factory equipment, and supplies the diluted chemical solution to the substrate processing unit 100. In this example, the diluting drug solution is hydrofluoric acid (dilute hydrofluoric acid) having a concentration of 5000 ppm. The concentration of dilute hydrofluoric acid is preferably stabilized with an accuracy of 5000 ± 5 ppm. The detailed configuration of the chemical solution generation unit 200 will be described later.

The control unit 310 includes a CPU (Central Processing Unit) and a memory, a microcomputer, and the like. The drug solution replenishment program described later is stored in the memory of the control unit 310. The control unit 310 controls various components in the substrate processing unit 100 and the chemical solution generation unit 200.

The substrate processing unit 100 is a single-wafer type apparatus that processes (etches in this example) the substrate W one by one using the chemical solution generated by the chemical solution generation unit 200, and is an indexer block 110 and a first processing block. It includes 120, a transport block 130, a second processing block 140, and a third processing block 150. The indexer block 110, the first processing block 120, the transport block 130, the second processing block 140, and the third processing block 150 are arranged so as to be arranged in this order in the X direction.

The indexer block 110 includes a plurality of carrier mounting portions 111 and a conveying portion 112. A carrier 113 for accommodating a plurality of substrates W in multiple stages is mounted on each carrier mounting portion 111. The transport unit 112 is provided with a transport mechanism (transport robot) 114 that transports the substrate W while holding the substrate W.

The first processing block 120 includes processing chambers 121 and 122 and a delivery unit 123. The processing chamber 121 and the processing chamber 122 are provided so as to face each other with the delivery portion 123 in the Y direction. Each of the processing chambers 121 and 122 is provided with a plurality of processing units 10 for processing the substrate W. The substrate W to be delivered between the transfer mechanism 114 and the transfer mechanism 132, which will be described later, is temporarily placed on the transfer unit 123. A plurality of substrates W may be placed on the delivery unit 123. The transport block 130 includes a transport chamber 131. The transport chamber 131 is provided with a transport mechanism 132 that transports the substrate W while holding the substrate W.

The second processing block 140 includes processing chambers 141 and 142 and a delivery unit 143. The processing chamber 141 and the processing chamber 142 are provided so as to face each other with the delivery portion 143 in the Y direction. A plurality of processing units 10 are provided in each of the processing chambers 141 and 142. The substrate W to be delivered between the transfer mechanism 132 and the transfer mechanism 154, which will be described later, is temporarily placed on the transfer section 143. A plurality of substrates W may be placed on the delivery unit 143. In this example, the delivery unit 143 can carry (shuttle transport) a predetermined distance in the X direction while holding the substrate W.

The third processing block 150 includes processing chambers 151 and 152 and a transport chamber 153. The processing chamber 151 and the processing chamber 152 are provided so as to face each other with the transport chamber 153 in the Y direction. A plurality of processing units 10 are provided in each of the processing chambers 151 and 152. The transport chamber 153 is provided with a transport mechanism 154 that transports the substrate W while holding the substrate W.

FIG. 2 is a side view showing the internal configuration of the processing chambers 121, 141, 151 of FIG. As shown in FIG. 2, in each of the processing chambers 121, 141, 151, a plurality of (four in this example) processing units 10 are arranged so as to be stacked in the Z direction. Similarly, in each of the processing chambers 122, 142, and 152 of FIG. 1, a plurality of (4 in this example) processing units 10 are arranged so as to be stacked in the Z direction. Therefore, in this example, 24 processing units 10 are provided in the substrate processing unit 100.

Each processing unit 10 includes a spin chuck 11, a chemical nozzle 12, and a cup 13. The spin chuck 11 is rotationally driven by a drive device (for example, an electric motor) (not shown) while holding the substrate W. The chemical solution nozzle 12 supplies the chemical solution generated by the chemical solution generation unit 200 to the substrate W rotated by the spin chuck 11. As a result, the substrate W is etched. The cup 13 is provided so as to surround the spin chuck 11 and receives a chemical solution that is shaken off from the substrate W during substrate processing.

The operation of the substrate processing unit 100 will be described with reference to FIGS. 1 and 2. The carrier 113 in which the unprocessed substrate W is housed is mounted on the carrier mounting portion 111 of the indexer block 110. The transport mechanism 114 transports the unprocessed substrate W from the carrier 113 to the delivery portion 123 of the first processing block 120. Further, the transport mechanism 114 transports the etched substrate W mounted on the delivery portion 123 to the carrier 113.

The transport mechanism 132 of the transport block 130 uses the unprocessed substrate W placed on the delivery unit 123 of the processing unit 10 or the second processing block 140 in the processing chambers 121 and 122 of the first processing block 120. It is transported to the delivery unit 143. Etching is performed on the substrate W conveyed to the processing unit 10 of any of the processing chambers 121 and 122. Further, the transport mechanism 132 transports the etched substrate W mounted on any of the processing units 10 or the delivery section 143 in the processing chambers 121 and 122 to the delivery section 123.

The transport mechanism 154 of the third processing block 150 uses the unprocessed substrate W mounted on the delivery unit 143 in either the processing chambers 141, 142, 151, 152 of the second or third processing blocks 140, 150. Is transported to the processing unit 10. Etching is performed on the substrate W conveyed to the processing unit 10 of any of the processing chambers 141, 142 and 151, 152. Further, the transport mechanism 154 transports the etched substrate W mounted on any of the processing units 10 in the processing chambers 141, 142, 151, 152 to the delivery unit 143.

In this example, of the 24 processing units 10, for example, a maximum of 18 processing units 10 etch the substrate W at the same time. Further, about 4 L of a chemical solution is used for each substrate W. Therefore, the substrate processing unit 100 consumes a large amount (72 L in this example) of the chemical solution all at once. Therefore, the chemical solution generation unit 200 is required to generate a large amount of chemical solution and supply it to the substrate processing unit 100.

(2) Configuration of Chemical Solution Generation Unit FIG. 3 is a diagram showing the configuration of the chemical solution generation unit 200 of FIG. As shown in FIG. 3, the chemical solution generation unit 200 mainly includes two chemical solution tanks 210 and 220, a mixing tank 230, a waste liquid tank 240, and a plurality of pipes. In the following description, the direction in which the drug substance solution, the diluting solution or the diluting drug solution flows in each pipe is defined as the downstream direction, and the opposite direction is defined as the upstream direction. Each of the chemical solution tanks 210 and 220 is, for example, a tank having a capacity of 2.4 L for storing the drug substance solution. The supply pipe 20, the pressurizing pipe 30, and the supply pipe 40 are connected to the chemical liquid tanks 210 and 220.

The supply pipe 20 has one main pipe 21 and two branch pipes 22 and 23. The upstream end of the main pipe 21 is connected to the chemical supply source 301. The branch pipes 22 and 23 are connected between the downstream end of the main pipe 21 and the chemical liquid tanks 210 and 220, respectively. A filter 24 is inserted in the main pipe 21. Valves 25 and 26 are inserted into the branch pipes 22 and 23, respectively. When the valve 25 is opened, the drug substance solution is supplied from the drug solution supply source 301 to the drug solution tank 210 through the filter 24 and stored. Similarly, when the valve 26 is opened, the drug substance solution is supplied from the drug solution supply source 301 to the drug solution tank 220 through the filter 24 and stored.

The pressurizing pipe 30 has one main pipe 31 and two branch pipes 32 and 33. The upstream end of the main pipe 31 is connected to the nitrogen gas supply source 303. The branch pipes 32 and 33 are connected between the downstream end of the main pipe 31 and the chemical liquid tanks 210 and 220, respectively. Valves 34 and 35 are inserted into the branch pipes 32 and 33, respectively. When the valves 34 and 35 are opened, nitrogen gas is supplied from the nitrogen gas supply source 303 to the chemical liquid tanks 210 and 220, respectively. As a result, the drug substance solution stored in the chemical solution tanks 210 and 220 is pumped downstream through the supply pipe 40.

The supply pipe 40 has one main pipe 41 and two branch pipes 42, 43. The branch pipes 42 and 43 are connected between the upstream end of the main pipe 41 and the chemical liquid tanks 210 and 220, respectively. The downstream end of the main pipe 41 is connected to a mixing pipe 60 described later. A flow meter 44 and an adjusting unit 45 are inserted in the main pipe 41. The flow meter 44 measures the flow rate of the drug substance solution flowing through the main pipe 41, and gives the measured flow rate to the control unit 310. The adjusting unit 45 is, for example, a motor needle valve or an LFC (Liquid Flow Controller), and adjusts the flow rate of the drug substance solution flowing through the main pipe 41 based on the control by the control unit 310. The flow rate of the drug substance solution supplied from each of the chemical solution tanks 210 and 220 is relatively small. Therefore, the inner diameters of the main pipe 41 and the branch pipes 42 and 43 are relatively small (for example, 4 mm to 8 mm).

The supply pipe 50 is provided so as to connect between the dilution liquid supply source 302 and the mixing pipe 60. A valve 51, a flow meter 52, and an adjusting unit 53 are inserted in the supply pipe 50. When the valve 51 is opened, the dilution liquid supplied from the dilution liquid supply source 302 flows through the supply pipe 50. The flow rate of the dilution liquid supplied from the dilution liquid supply source 302 is relatively large (for example, 50 L / min to 75 L / min). Therefore, the inner diameter of the supply pipe 50 is relatively large (for example, 1 inch). The flow meter 52 measures the flow rate of the diluting liquid flowing through the supply pipe 50, and gives the measured flow rate to the control unit 310. The adjusting unit 53 is, for example, an electric pressure regulating regulator, and adjusts the flow rate of the diluting liquid flowing through the supply pipe 50 based on the control by the control unit 310.

The mixing tank 230 is, for example, a tank having a capacity of 68 L, which stores a mixed solution of the drug substance solution and the diluting solution as a diluting drug solution. A mixing pipe 60, a pressurized pipe 70, a drainage pipe 80, and a mixing pipe 90 are connected to the mixing tank 230.

The mixing pipe 60 has one main pipe 61 and two branch pipes 62 and 63. The upstream end of the main pipe 61 is connected to the downstream end of the supply pipe 50 and the downstream end of the main pipe 41 of the supply pipe 40. The branch pipe 62 is connected between the downstream end of the main pipe 61 and the mixing tank 230. The branch pipe 63 is connected between the downstream end of the main pipe 61 and the waste liquid tank 240. Valves 64 and 65 are inserted into the branch pipes 62 and 63, respectively.

In the main pipe 61, the diluent liquid supplied from the dilution liquid supply source 302 and the drug substance liquid led from the supply pipe 40 are mixed to efficiently generate the diluent liquid. The diluting chemical solution produced in the main pipe 61 is supplied to and stored in the mixing tank 230 through the branch pipe 62.

Immediately after the start and end of production of the diluent, the flow rate of the diluent or drug substance is not stable due to the time difference between opening and closing the valves 34, 35, 51, etc., so the concentration of the diluted solution becomes unstable. Sometimes. Therefore, immediately after the start of generation of the diluted chemical solution, the diluted chemical solution having an unstable concentration is discarded in the waste liquid tank 240 because the valve 65 is opened and the valve 64 is closed for a predetermined time (for example, 3 seconds to 5 seconds). (Predrain). Immediately after the production of the diluted chemical solution is completed, the diluted chemical solution having an unstable concentration is discarded in the waste liquid tank 240 because the valve 65 is opened and the valve 64 is closed for a predetermined time (for example, 1 second). drain). As a result, the diluted chemical solution having a stable concentration can be supplied to the mixing tank 230.

The pressurizing pipe 70 is connected between the nitrogen gas supply source 304 and the mixing tank 230. A valve 71 is inserted in the pressurizing pipe 70. When the valve 71 is opened, nitrogen gas is supplied to the mixing tank 230 from the nitrogen gas supply source 304. As a result, the diluting chemical solution stored in the mixing tank 230 is discarded in the waste liquid tank 240 through the drainage pipe 80.

The drainage pipe 80 is connected between the mixing tank 230 and the waste liquid tank 240. A valve 81 is inserted in the drainage pipe 80. When the valve 81 is opened, the excess diluent liquid stored in the mixing tank 230 is discarded in the waste liquid tank 240.

The mixing pipe 90 has one main pipe 91 and two branch pipes 92 and 93. The upstream end of the main pipe 91 is connected to the mixing tank 230. The branch pipe 92 is a circulation pipe used for circulating the diluted chemical solution, and is connected between the downstream end of the main pipe 91 and the mixing tank 230. The branch pipe 93 is a processing pipe used for processing the substrate W, and is connected between the downstream end portion of the main pipe 91 and the substrate processing portion 100. A densitometer 94 and a heater 95 are inserted in the main pipe 91. A pump 96, a filter 97 and a valve 98 are inserted in the branch pipe 92. A valve 99 is inserted into the branch pipe 93.

The densitometer 94 measures the concentration of the diluting chemical solution flowing through the main pipe 91, and gives the measured concentration to the control unit 310. The measurement result by the densitometer 94 is used for controlling the adjusting unit 53. When the pump 96 is driven and the valve 98 is opened, the diluting chemical solution from the mixing tank 230 is heated by the heater 95 and then circulated to the mixing tank 230 through the filter 97. When the valve 99 is opened, the diluting chemical solution from the mixing tank 230 is heated by the heater 95 and then supplied to the substrate processing unit 100.

The mixing tank 230 is provided with four liquid level sensors 231,232, 233, 234. The liquid level sensors 231, 232, 233, and 234 are arranged so as to detect the first, second, third, and fourth liquid levels of the diluent liquid stored in the mixing tank 230, respectively. In this example, the first, second, third, and fourth liquid levels are the liquid levels when the volumes of the diluent liquid stored in the mixing tank 230 are 5 L, 45 L, 60 L, and 65 L, respectively. Further, the liquid level sensors 231 to 234 give the detection result to the control unit 310.

Based on the detection results of the liquid level sensors 232 and 233, the control unit 310 controls the valves 34 and 35 so that the drug substance liquid is alternately supplied from the chemical liquid tanks 210 and 220 to the mixing tank 230, and the diluting liquid. The valve 51 is controlled so that the dilution liquid is supplied from the supply source 302 to the mixing tank 230. As a result, a predetermined range of diluted chemical solution is constantly stored in the mixing tank 230. Therefore, even when a large amount of the diluent is consumed by the substrate processing unit 100, the diluent can be supplied to the substrate processing unit 100.

(3) Operation of the chemical solution generator The flow rate of the drug substance solution supplied from the supply pipe 40 and the flow rate of the dilution liquid supplied from the supply pipe 50 are mixed at a predetermined ratio (about 1: 100). It is considered that a diluting drug solution having the above concentration (about 5000 ppm) is produced. However, simply maintaining a constant ratio between the flow rate of the drug substance and the flow rate of the diluent cannot produce a diluted drug solution whose concentration is stabilized with the above high accuracy (5000 ± 5 ppm). found.

As a result of repeating various experiments and discussions, the present inventors have found that fluctuations in the pressure of the diluent solution supplied from the dilution solution supply source 302, which is a factory facility, affect the stability of the concentration of the diluent solution. I got the knowledge that there is. Due to fluctuations in the pressure of the diluent, the flow rate of the diluent fluctuates over a long period of time in a cycle of 1 to 2 weeks. Such fluctuations in the pressure of the diluent from the factory equipment cannot be predicted by the user and cannot be controlled.

Therefore, in the present embodiment, the first threshold range is set with respect to the concentration. The first threshold range is a range between a preset first lower threshold and a preset first upper threshold. If the concentration measured by the densitometer 94 continues to be outside the first threshold range for a certain period of time, the first flag is turned on. On the other hand, even when the concentration measured by the densitometer 94 is outside the first threshold range, if the state does not continue for a certain period of time, the first flag is turned off.

When the second liquid level is detected by the liquid level sensor 232, the supply (replenishment) of the diluted chemical solution to the mixing tank 230 is started. Here, when the first flag is off, the diluent solution is mixed by the drug substance solution supplied at a preset flow rate and the dilution solution supplied at a preset flow rate to obtain the diluent solution. The generated diluent solution is replenished in the mixing tank 230.

On the other hand, when the first flag is on, the flow rate of the diluting liquid is corrected (for example, offset correction) according to the measured concentration. A diluent is generated by mixing the drug substance solution supplied at a preset flow rate and the diluent solution supplied at the flow rate corrected as described above, and the generated diluent solution is mixed in the mixing tank 230. Is replenished to. As a result, even when the pressure of the diluting solution fluctuates, it is possible to generate a diluted drug solution having a high concentration and stabilization with high accuracy with simple control. Replenishment of the diluted drug solution is continued until the liquid level sensor 232 detects a third liquid level.

In the present embodiment, when the first liquid level is detected by the liquid level sensor 231 or when the fourth liquid level is detected by the liquid level sensor 234, the control of the chemical liquid generation unit 200 is performed. Is stopped. At this time, an alarm may be output. The output of the alarm may be, for example, an alarm sound generated by an alarm or the like, or an alarm display by a lamp or the like.

Further, in the present embodiment, a second threshold range is set for the concentration. The second threshold range is the range between the preset second lower threshold and the preset second upper threshold. The second lower threshold is smaller than the first lower threshold and the second upper threshold is greater than the first upper threshold.

If the concentration measured by the densitometer 94 continues to be outside the second threshold range for a certain period of time, the second flag is turned on. On the other hand, even when the concentration measured by the densitometer 94 is outside the second threshold range, if the state does not continue for a certain period of time, the second flag is turned off. When the second flag is turned on, the control of the chemical solution generation unit 200 is stopped. In this case, it is possible to suppress the formation of a diluted chemical solution whose concentration is not stable. At this time, the same alarm as described above may be output.

(4) Chemical Solution Replenishment Process FIG. 4 is a diagram showing the configuration of the control unit 310. 5 and 6 are flowcharts showing an algorithm of the chemical replenishment process performed by the chemical replenishment program. As shown in FIG. 4, the control unit 310 includes a concentration acquisition unit 311, a flag switching unit 312, a liquid level acquisition unit 313, a flow rate determination unit 314, a chemical solution generation unit 315, a drain execution unit 316, and a chemical solution replenishment unit 317.

The functional unit of the control unit 310 is realized by the CPU of the control unit 310 executing the chemical solution replenishment program stored in the memory. A part or all of the functional units of the control unit 310 may be realized by hardware such as an electronic circuit. Hereinafter, the chemical solution replenishment process will be described with reference to the control unit 310 of FIG. 4 and the flowcharts of FIGS. 5 and 6. In the initial state, all valves except the valve 98 are closed, and the first and second flags are off. Further, the pump 96 is always driven. Therefore, the diluting chemical solution stored in the mixing tank 230 is constantly circulated through the branch pipe 92 (circulation pipe).

First, the concentration acquisition unit 311 acquires the concentration of the diluted chemical solution measured by the concentration meter 94 (step S1). Step S1 is periodically repeated until step S12, which will be described later, is executed. Next, the flag switching unit 312 determines whether or not the concentration acquired by the concentration acquisition unit 311 is outside the first threshold range (step S2). When the concentration is not outside the first threshold range, the liquid level acquisition unit 313 determines whether or not the second liquid level has been detected by the liquid level sensor 232 (step S3).

If the second liquid level is not detected, the liquid level acquisition unit 313 returns to step S2. Steps S2 and S3 are repeated until the concentration falls outside the first threshold range or a second liquid level is detected. When the second liquid level is detected in step S3, the flow rate determining unit 314 determines the flow rate of the diluting liquid to a preset flow rate because the first flag is off (step S4). After that, the process proceeds to step S12.

When the concentration is out of the first threshold range in step S2, the flag switching unit 312 determines whether or not a certain time has elapsed (step S5). If the fixed time has not elapsed, the flag switching unit 312 returns to step S2. Steps S2 and S5 are repeated until the concentration is no longer outside the first threshold range or a certain period of time has elapsed. When a certain time has elapsed in step S5, the flag switching unit 312 turns on the first flag (step S6).

Subsequently, the flag switching unit 312 determines whether or not the concentration has returned within the first threshold range (step S7). When the concentration returns to within the first threshold range, the flag switching unit 312 determines whether or not a certain time has elapsed (step S8). If the fixed time has not elapsed, the flag switching unit 312 returns to step S7. Steps S7 and S8 are repeated until the concentration is maintained outside the first threshold range or a certain period of time elapses. When a certain time has elapsed in step S8, the flag switching unit 312 turns off the first flag (step S9) and returns to step S1.

If the concentration does not return within the first threshold range in step S7, the liquid level acquisition unit 313 determines whether or not the second liquid level has been detected by the liquid level sensor 232 (step S10). If the second liquid level is not detected, the liquid level acquisition unit 313 returns to step S7. Steps S7 and S10 are repeated until the concentration returns to within the first threshold range or a second liquid level is detected.

When the second liquid level is detected in step S10, the flow rate determining unit 314 determines the correction amount of the flow rate of the diluting liquid according to the acquired concentration because the first flag is on. The flow rate of the diluting liquid is determined based on the determined correction amount (step S11). After that, the process proceeds to step S12.

In step S12, the concentration acquisition unit 311 ends the acquisition of the concentration of the diluent chemical solution (step S12). Next, the chemical solution generation unit 315 starts the generation of the diluted chemical solution (step S13). Specifically, in step S13, the valve 34 or the valve 35 is opened so that the drug substance solution is supplied from the chemical solution tank 210 or the chemical solution tank 220 at a preset flow rate. Further, the valve 51 is opened so that the diluting liquid is supplied. Further, the adjusting unit 53 is controlled based on the flow rate measured by the flow meter 52 so that the flow rate of the diluting liquid becomes the flow rate determined in step S4 or step S11.

As a result, the diluent solution is generated by mixing the drug substance solution and the dilution solution in the main pipe 61 of the mixing pipe 60. In the present embodiment, the drug substance solution is supplied by alternately using the chemical solution tank 210 and the chemical solution tank 220 at each supply timing (timing when the second liquid level is detected) of the diluted chemical solution.

Next, the drain execution unit 316 starts pre-drain by opening the valve 65 (step S14). After a predetermined time, the drain execution unit 316 ends the pre-drain by closing the valve 65 (step S15). Subsequently, the chemical solution replenishment unit 317 starts replenishing the mixing tank 230 with the diluted chemical solution by opening the valve 64 (step S16).

After that, the liquid level acquisition unit 313 determines whether or not the third liquid level has been detected by the liquid level sensor 233 (step S17). If the third liquid level is not detected, the liquid level acquisition unit 313 waits until the third liquid level is detected. When the third liquid level is detected, the chemical solution replenishment unit 317 ends the replenishment of the diluted chemical solution to the mixing tank 230 by closing the valve 64 (step S18).

Next, the drain execution unit 316 starts post-drain by opening the valve 65 (step S19). Further, the chemical solution generation unit 315 ends the generation of the diluted chemical solution by closing the valves 34, 35, 51 (step S20). After a predetermined time, the drain execution unit 316 ends the post-drain by closing the valve 65 (step S21).

After that, the chemical solution generation unit 315 determines whether or not the set time (hereinafter, referred to as a check delay time) has elapsed (step S22). The check delay time is a time for further stabilizing the concentration of the diluting chemical solution stored in the mixing tank 230, and can be set, for example, from 0 seconds to 30 seconds. If the check delay time has not elapsed, the chemical generation unit 315 waits until the check delay time elapses. When the check delay time has elapsed, the process returns to step S1. After that, the above-mentioned chemical replenishment treatment is repeated. When the user gives a predetermined command, the chemical replenishment process ends.

In the above chemical replenishment process, the flag switching unit 312 constantly monitors the state of the second flag, and the process proceeds when the second flag is off. When the second flag is switched on, an alarm is output regardless of which process has been executed, and the chemical replenishment process ends. Further, when the first liquid level is detected by the liquid level sensor 231 or the fourth liquid level is detected by the liquid level sensor 234 in steps S3, S10, S18, etc., the chemical liquid replenishment process is also performed. finish.

(5) Effect In the substrate processing apparatus 300 according to the present embodiment, the dilution liquid is supplied by the supply pipe 50, and the drug substance solution is supplied by the supply pipe 40. Here, the dilution liquid is supplied from the dilution liquid supply source 302, which is a factory facility. Therefore, a large amount of dilution liquid can be supplied without increasing the size of the substrate processing apparatus 300. The flow rate of the diluting liquid flowing through the supply pipe 50 is adjusted by the adjusting unit 53.

In the mixing tank 230, the dilution solution supplied by the supply pipe 50 and the drug substance solution supplied by the supply pipe 40 are mixed. The concentration of the diluent solution in which the dilution solution and the drug substance solution are mixed is measured by the concentration meter 94. Since the densitometer 94 is provided in the mixing pipe 90 that supplies the diluent chemical solution to the substrate processing unit 100, the concentration of the diluent chemical solution used for the substrate treatment can be measured more accurately. The control unit 310 determines the correction amount of the flow rate of the dilution liquid so that the concentration measured by the densitometer 94 becomes a set value, and the determined correction amount is given to the adjustment unit 53.

According to this configuration, even if the flow rate of the diluting liquid fluctuates due to the fluctuation of the pressure of the diluting liquid, the correction amount determined so that the concentration measured by the densitometer 94 becomes the set value. The flow rate of the diluting liquid flowing through the supply pipe 50 is corrected by the adjusting unit 53 based on the above. As a result, in the mixing tank 230, it is possible to generate a diluted chemical solution whose concentration is stabilized with high accuracy.

Since the drug substance solution is supplied from the drug solution tanks 210 and 220 to the mixing tank 230 through the supply pipe 40, fluctuations in the pressure of the drug substance solution flowing through the supply pipe 40 are suppressed. Therefore, the flow rate of the drug substance solution flowing through the supply pipe 40 can be easily stabilized. As a result, it is possible to more easily produce a diluted chemical solution whose concentration is stabilized with high accuracy. Since the drug substance solution stored in the chemical solution tank 210 and the drug substance solution stored in the drug solution tank 220 are alternately supplied to the mixing tank 230, the drug substance solution is supplied to the mixing tank 230 without delaying the processing of the substrate W. Can be supplied.

Further, according to the above control, the user of the substrate processing apparatus 300 does not need to perform maintenance work such as manually adjusting the flow rates of the dilution solution and the drug substance solution. Therefore, it is not necessary to stop the operation of the substrate processing apparatus 300 for the above maintenance work. Thereby, the efficiency of substrate processing can be improved.

(6) Other Embodiments (a) In the above embodiment, the chemical solution generation unit 200 includes two chemical solution tanks 210 and 220 configured to alternately supply the drug substance solution to the mixing tank 230. The embodiment is not limited to this. The chemical solution generation unit 200 may include three or more chemical solution tanks configured to alternately supply the drug substance solution to the mixing tank 230. Alternatively, the chemical solution generation unit 200 may include only one chemical solution tank if a sufficient amount of the drug substance solution can be supplied to the mixing tank 230. Further, when the fluctuation of the pressure of the drug substance supplied from the chemical solution supply source 301 is small, the chemical solution generation unit 200 may not include the chemical solution tank.

(B) In the above embodiment, the chemical solution generation unit 200 includes an adjustment unit 45 that adjusts the flow rate of the drug substance solution flowing through the supply pipe 40, but the embodiment is not limited to this. When the flow rate of the drug substance solution flowing through the supply pipe 40 is stable, the drug solution generation unit 200 may not include the adjustment unit 45.

(C) In the above embodiment, the chemical solution generation unit 200 includes the mixing pipe 60, but the embodiment is not limited to this. The chemical solution generation unit 200 does not have to include the mixing pipe 60. In this case, each of the downstream end of the supply pipe 50 and the downstream end of the main pipe 41 of the supply pipe 40 is directly connected to the mixing tank 230.

(D) In the above embodiment, the densitometer 94 is provided in the mixing pipe 90, but the embodiment is not limited to this. The densitometer 94 may be provided in any part of the chemical solution generation unit 200 as long as the concentration of the diluted chemical solution can be measured. Therefore, the densitometer 94 may be inserted in the mixing pipe 60 or may be arranged in the mixing tank 230.

(E) In the above embodiment, the chemical solution generation unit 200 produces dilute hydrofluoric acid as a diluting chemical solution, but the embodiment is not limited to this. The chemical solution generation unit 200 may generate other diluted chemical solutions such as dilute phosphoric acid.

(F) In the above embodiment, the substrate processing unit 100 performs etching as a substrate treatment using a diluent, but the embodiment is not limited to this. The substrate processing unit 100 may perform other substrate processing (for example, substrate cleaning) using a diluting chemical solution.

(7) Example As an example, dilute hydrofluoric acid was produced as a diluted chemical solution by the chemical solution generation unit 200 according to the above embodiment. On the other hand, as a comparative example, dilute hydrofluoric acid was produced as a diluting drug solution without the adjusting unit 53 correcting the flow rate of the diluting solution. In addition, the concentration of dilute hydrofluoric acid produced in each of the examples and comparative examples was measured.

As a result, in the examples, the concentration of dilute hydrofluoric acid was 5000 ± 5 ppm. On the other hand, in the comparative example, the concentration of dilute hydrofluoric acid was 5000 ± 10 ppm. From these results, it was confirmed that the concentration-stabilized dilute hydrofluoric acid can be produced with high accuracy by correcting the flow rate of the diluting liquid by the adjusting unit 53.

Further, the substrate W was etched using the dilute hydrofluoric acid produced in each of the examples and the comparative examples. As a result, when the dilute hydrofluoric acid produced in the examples was used, the amount of variation in etching of the substrate W was 2 Å. On the other hand, when the dilute hydrofluoric acid produced in the comparative example was used, the amount of variation in etching of the substrate W was 5 Å. As a result, it was confirmed that the fluctuation amount of etching can be improved by 60% by using dilute hydrofluoric acid whose concentration is stabilized with high accuracy.

(8) Correspondence relationship between each component of the claim and each part of the embodiment In the above embodiment, the substrate W is an example of a substrate, the substrate processing apparatus 300 is an example of a substrate processing apparatus, and the supply piping. 50 and 40 are examples of the first and second pipes, respectively. The main pipe 61 and the branch pipe 62 in the mixing pipe 60 are examples of the third pipe, the branch pipe 63 in the mixing pipe 60 is an example of the fourth pipe, and the mixing pipe 90 is an example of the fifth pipe.

The adjusting unit 53 is an example of the first adjusting unit or the adjusting unit, the adjusting unit 45 is an example of the second adjusting unit, the mixing tank 230 is an example of the mixing tank, and the densitometer 94 is an example of the densitometer. The control unit 310 is an example of the control unit. The chemical solution tank 210 is an example of a chemical solution tank or a first chemical solution tank, the chemical solution tank 220 is an example of a chemical solution tank or a second chemical solution tank, and the substrate processing unit 100 is an example of a substrate processing unit.

10 ... Processing unit, 11 ... Spin chuck, 12 ... Chemical nozzle, 13 ... Cup, 20, 40, 50 ... Supply piping, 21, 31, 41, 61, 91 ... Main pipe, 22, 23, 32, 33, 42, 43, 62, 63, 92, 93 ... Branch pipe, 24, 97 ... Filter, 25, 26, 34, 35, 51, 64, 65, 71, 81, 98, 99 ... Valve, 30, 70 ... Pressurized piping , 44, 52 ... Flow meter, 45, 53 ... Adjustment unit, 60, 90 ... Mixing pipe, 80 ... Drainage pipe, 94 ... Densitometer, 95 ... Heater, 96 ... Pump, 100 ... Board processing, 110 ... Indexer block , 111 ... Carrier mounting unit, 112, 131, 153 ... Transfer chamber, 113 ... Carrier, 114, 132, 154 ... Transfer mechanism, 120 ... First processing block, 121, 122, 141, 142, 151, 152 ... Processing chamber, 123, 143 ... Delivery section, 130 ... Transfer block, 140 ... Second processing block, 150 ... Third processing block, 200 ... Chemical solution generation section, 210, 220 ... Chemical solution tank, 230 ... Mixing tank, 231 ~ 234 ... Liquid level sensor, 240 ... Waste liquid tank, 300 ... Substrate processing device, 301 ... Chemical solution supply source, 302 ... Dilution liquid supply source, 303, 304 ... Nitrogen gas supply source, 310 ... Control unit, 311 ... Concentration acquisition Unit, 312 ... Flag switching unit, 313 ... Liquid level acquisition unit, 314 ... Flow rate determination unit, 315 ... Chemical solution generation unit, 316 ... Drain execution unit, 317 ... Chemical solution replenishment unit, W ... Substrate

Claims (15)

A substrate processing device that processes a substrate using a diluted chemical solution.
The first pipe that supplies the dilution liquid and
The second pipe that supplies the chemical solution and
A first adjusting unit for adjusting the flow rate of the diluting liquid flowing through the first pipe, and
A mixing tank that mixes the dilution solution supplied by the first pipe and the chemical solution supplied by the second pipe.
A densitometer that measures the concentration of the drug solution in the mixture of the dilution solution and the drug solution,
A control unit is provided which determines a correction amount of the flow rate of the dilution liquid so that the concentration measured by the densitometer becomes a set value and gives the determined correction amount to the first adjusting unit.
The first adjusting unit is a substrate processing device that corrects the flow rate of the diluting liquid flowing through the first pipe based on the correction amount given by the control unit. Equipped with a chemical tank for storing chemicals
The substrate processing apparatus according to claim 1, wherein the second pipe is connected to the chemical solution tank and supplies the chemical solution stored in the chemical solution tank to the mixing tank. The chemical solution tank includes a first chemical solution tank and a second chemical solution tank.
The substrate treatment according to claim 2, wherein the chemical solution stored in the first chemical solution tank and the chemical solution stored in the second chemical solution tank are alternately supplied to the mixing tank by the second pipe. apparatus. Any one of claims 1 to 3, further comprising a third pipe that leads the mixing tank to the mixing tank while mixing the dilution liquid supplied by the first pipe and the chemical liquid supplied by the second pipe. The substrate processing apparatus according to the section. It is provided so as to branch off from the third pipe, and the mixed liquid of the diluting liquid supplied by the first pipe and the chemical liquid supplied by the second pipe is discharged without being guided to the mixing tank. The substrate processing apparatus according to claim 4, further comprising a fourth pipe. The substrate processing apparatus according to any one of claims 1 to 5, wherein the first adjusting unit is an electric pressure regulating regulator. The substrate processing apparatus according to any one of claims 1 to 6, further comprising a second adjusting unit for adjusting the flow rate of the chemical solution flowing through the second pipe. The substrate processing apparatus according to claim 7, wherein the second adjusting unit is a motor needle valve. The substrate processing apparatus according to any one of claims 1 to 8, wherein the inner diameter of the first pipe is larger than the inner diameter of the second pipe. A first threshold range is set for the concentration of the drug solution,
The control unit determines the correction amount of the flow rate of the dilution liquid when the concentration measured by the densitometer is outside the first threshold range, according to any one of claims 1 to 9. The substrate processing apparatus described. A second threshold range is set that includes the first threshold range for the concentration of the drug solution.
When the concentration measured by the densitometer is outside the second threshold range,
The substrate processing apparatus according to claim 10, wherein the supply of the diluting liquid through the first pipe and the supply of the chemical liquid through the second pipe are stopped. The substrate processing apparatus according to any one of claims 1 to 11, wherein the first pipe is connected to equipment for supplying a dilution liquid in a factory where the substrate processing apparatus is installed. The board processing unit that processes the board and
Further, a fifth pipe for supplying the mixed liquid stored in the mixing tank to the substrate processing unit is provided.
The substrate processing apparatus according to any one of claims 1 to 12, wherein the densitometer is provided so as to measure the concentration of a chemical solution in the mixed solution flowing through the fifth pipe. This is a substrate processing method in which a substrate is processed using a diluted chemical solution.
The step of supplying the dilution liquid through the first pipe,
The step of supplying the chemical solution through the second pipe,
The step of adjusting the flow rate of the diluting liquid flowing through the first pipe by the adjusting unit, and
In the mixing tank, the step of mixing the dilution solution supplied by the first pipe and the chemical solution supplied by the second pipe, and
Steps to measure the concentration of the drug solution in the mixture of the dilution solution and the drug solution with a densitometer,
The step includes a step of determining a correction amount of the flow rate of the diluting liquid so that the concentration measured by the densitometer becomes a set value, and giving the determined correction amount to the adjusting unit.
The step of adjusting the flow rate of the diluting liquid by the adjusting unit is
A substrate processing method comprising correcting the flow rate of a diluent liquid flowing through the first pipe by the adjusting unit based on a given correction amount. A threshold range is set for the concentration of the drug solution,
13. The correction amount according to claim 14, wherein determining the correction amount includes determining the correction amount when the concentration measured by the densitometer is out of the threshold range for a predetermined time or longer. Substrate processing method.

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