Method and apparatus for adjusting the concentration of a drug solution

Abstract

The present invention provides a method and apparatus for adjusting the concentration of a chemical solution that allows for high-precision concentration adjustment with fewer control items and without requiring a long time for adjustment. [Solution] The concentration adjustment method is a method for adjusting a chemical solution of a predetermined concentration by mixing a stock solution containing any component with pure water, and includes the steps of: (A) mixing a predetermined amount of stock solution and pure water to obtain a mixed solution with a concentration in the range of 50% to 200% of a preset target concentration; (B) stirring the obtained mixed solution for a predetermined time and measuring the conductivity and liquid temperature of the mixed solution in the system to obtain a concentration value; and (C) calculating the amount of stock solution or pure water required to make the concentration value obtained in step (B) the median concentration between the concentration value and the target concentration, and supplying the calculated amount of stock solution or pure water to the mixed solution, and repeating steps (B) and (C) until the obtained concentration value is within a predetermined range of the preset target concentration.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for adjusting the concentration of chemical solutions such as a developer used in photolithography.

Background Art

[0002] For example, in the manufacturing process of precision parts such as semiconductors, photolithography is performed. Photolithography is a technique for forming a pattern by applying a photosensitive substance (photoresist), exposing it, and developing it. In the development process of the photoresist, an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) is used as a developer. Since the concentration of the developer affects the dimensional accuracy of the pattern and the film thickness accuracy of the unexposed portion in the development process, high accuracy is required for adjusting the concentration of the developer.

[0003] Conventionally, the concentration of the developer is adjusted by diluting the stock solution with pure water to a predetermined concentration. For example, Patent Document 1 describes a method of preparing a mixed solution of a predetermined concentration by diluting a stock solution of an acid or an alkali with pure water, including: (A) an initial preparation step of mixing a predetermined amount of the stock solution and pure water to prepare a mixed solution having a concentration different from a preset target concentration; (B) a concentration measurement step of measuring the concentration of the mixed solution by potentiometric titration; and (C) a preparation step of calculating the shortage amount of the stock solution or pure water based on the difference between the concentration value measured in step (B) and the target concentration value, and supplying 85 to 99% of the calculated shortage amount of the stock solution or pure water to the mixed solution, and repeating steps (B) and (C) until the measured concentration value falls within the range of the preset target concentration.

[0004] Patent Document 2 describes an automatic dilution apparatus equipped with a load cell for measuring the weight of the liquid volume in a mixing tank and an automatic titration device using potentiometric measurement. Patent Document 3 describes a method for adjusting a developer by supplying a stock solution and pure water to a mixing tank supported by a load cell, mixing them, taking a portion of the mixture and analyzing its concentration by a chemical or physical method, and then supplying stock solution or pure water based on this analysis value. Patent Document 4 describes an automatic dilution apparatus using a load cell and an ultrasonic densitometer. Patent Document 5 also describes a dilution apparatus that adjusts the concentration by measuring conductivity. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-180076 [Patent Document 2] Japanese Patent Application Publication No. 5-216241 [Patent Document 3] Japanese Patent Application Publication No. 6-29207 [Patent Document 4] Japanese Patent Application Publication No. 6-61136 [Patent Document 5] Japanese Patent Application Publication No. 64-27624 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the above-mentioned Patent Documents 1 and 2, potentiometric titration is used for adjusting the concentration of the developer. According to potentiometric titration, the concentration of alkaline components and other substances in the developer can be accurately measured, and the target concentration can be reached with high precision. However, while potentiometric titration offers high accuracy, it requires sampling from a preparation tank and performing a separate measurement procedure. As a result, the number of control items increases, including temperature control of the standard solution, and concentration adjustment tends to be time-consuming.

[0007] In the aforementioned Patent Documents 2-4, weight measurement using load cells is employed to control the supply amount of stock solution or pure water. However, weight measurement using load cells is limited by factors such as the difference in head pressure between the stock solution and pure water, and the minimum measurable weight, making it difficult to accurately supply the desired amount. As a result, the number of control items required to ensure the accuracy of the supply amount tends to increase, and the time required for concentration adjustment also tends to increase. Furthermore, a complex and expensive structure is required to support the tank body, and periodic calibration of the load cells is also essential.

[0008] Patent Document 5, described above, has the advantage of allowing for real-time and rapid concentration analysis of a mixed solution using the conductivity method. However, in the dilution apparatus described in Patent Document 5, the developer stock and additives in the stock tank and additive tank are continuously supplied from pipelines by respective pumps. These are then combined with pure water continuously supplied by a pure water pump in the piping before being sent to a stirring tank. The concentration is adjusted by increasing or decreasing the flow rate of the stock pump by a predetermined amount according to the measured conductivity. However, in this dilution apparatus, the amount of stock and other components added tends to be unstable, which increases the time required for concentration adjustment.

[0009] This invention has been made in view of these circumstances, and aims to provide a method and apparatus for adjusting the concentration of a chemical solution that can adjust the concentration with high precision, with fewer control items and without requiring a long time for adjustment. [Means for solving the problem]

[0010] The present invention provides a method for adjusting the concentration of a chemical solution, comprising the steps of: (A) mixing a predetermined amount of stock solution containing any component with pure water to adjust a chemical solution to a predetermined concentration; (B) stirring the mixture obtained in step (A) for a predetermined time, measuring the conductivity and temperature of the mixture within the system to obtain a concentration value; and (C) calculating the amount of stock solution or pure water required to make the concentration the midpoint between the concentration value obtained in step (B) and the target concentration, and supplying the calculated amount of stock solution or pure water to the mixture, wherein steps (B) and (C) are repeated until the obtained concentration value falls within a predetermined range of the target concentration.

[0011] In the present invention, the chemical solution is a chemical solution that contains any component such as an acid component or an alkaline component and exhibits conductivity, and specific examples include TMAH and hydrofluoric acid aqueous solution.

[0012] The above step (C) is a step of supplying a stock solution or pure water through a plurality of supply pipes having at least two or more different diameters, characterized in that the amount of stock solution or pure water is adjusted by controlling the opening time of an automatic on / off valve provided in the supply pipe.

[0013] The above step (B) is characterized by circulating the mixed liquid in the tank body through circulation piping in the adjustment tank, and measuring the conductivity and liquid temperature of the mixed liquid introduced into the circulation piping to obtain a concentration value.

[0014] The present invention relates to a chemical solution concentration adjustment device that adjusts a chemical solution to a predetermined concentration by mixing a stock solution containing any component with pure water, and comprises: an adjustment tank having a tank body; a stock solution supply device that supplies the stock solution to the tank body through a plurality of supply pipes having at least two or more different diameters and equipped with an automatic on-off valve; a pure water supply device that supplies pure water to the tank body through a plurality of supply pipes having at least two or more different diameters and equipped with an automatic on-off valve; a measuring device that measures the conductivity and liquid temperature of the mixed liquid in the adjustment tank to obtain a concentration value; and a control device that controls the opening time of the automatic on-off valve, wherein the control device compares the concentration value obtained by the measuring device with a predetermined threshold value for the target concentration, and if the obtained concentration value is outside the predetermined threshold value, calculates the amount of stock solution or pure water required to bring the obtained concentration value to the median concentration between the obtained concentration value and the target concentration, activates the automatic on-off valve, and supplies the calculated amount of stock solution or pure water to the tank body. [Effects of the Invention]

[0015] The present invention provides a method for adjusting the concentration of a drug solution, which includes steps (A), (B), and (C) described above. Steps (B) and (C) are repeated until the obtained concentration value falls within a predetermined range of the target concentration. This allows the entire concentration adjustment process to be carried out in situ, reducing the number of control items. Furthermore, the median between the obtained concentration value and the target concentration is set as a provisional target concentration, and this process is repeated to adjust the concentration stepwise. In each iteration, the difference between the current concentration and the target concentration is dynamically calculated, and an asymptotic correction is applied to control the convergence rate. This correction is based on an algorithm that reduces the correction value as the error decreases, stabilizing the concentration adjustment while preventing oscillations and overcorrection. Theoretically, the adjustment process is shown to have linear or quadratic convergence, guaranteeing convergence. As a result, the concentration reliably reaches the predetermined concentration range and ultimately asymptotically converges to the target concentration.

[0016] The above step (C) is a step of supplying the stock solution or pure water through a plurality of supply pipes having at least two or more different diameters. By adjusting the opening time of the automatic on-off valves provided in the supply pipes, the liquid volume of the stock solution or pure water is controlled, so that the accuracy of concentration adjustment can be ensured while simplifying the device configuration. For example, if it is necessary to ensure the accuracy of the input amount, a plurality of pump systems are required, and if it is necessary to control the input amount by weight, a large-scale weighing mechanism is required. However, compared with these, the configuration can be simplified, leading to a reduction in the device cost.

[0017] The above step (B) is a step of circulating the mixed liquid in the tank body in the adjustment tank through the circulation pipe and measuring the conductivity and liquid temperature of the mixed liquid introduced into the circulation pipe to obtain the concentration value of the above components. Therefore, without providing separate stirring means, the concentration value of the uniformly mixed mixed liquid can be accurately obtained.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic configuration diagram of one form of the chemical liquid concentration adjustment device of the present invention. [Figure 2] It is a process diagram showing an outline of the chemical liquid concentration adjustment method of the present invention. [Figure 3] It is a graph showing the concentration transition of an example of the chemical liquid concentration adjustment method of the present invention. [Figure 4] It is a graph showing the concentration transition in Examples 1-2.

Embodiments for Carrying Out the Invention

[0019] The chemical liquid obtained by the concentration adjustment method and concentration adjustment device of the present invention is used, for example, as a developer used in photolithography. There are acidic developers and alkaline developers. For example, acidic developers mainly contain organic acids and their salts and are used for developing photosensitive materials and specific photoresists. In addition, alkaline developers use inorganic alkaline aqueous solutions such as sodium hydroxide, potassium hydroxide, and sodium phosphate, and organic alkaline aqueous solutions such as TMAH.

[0020] The target concentration of the chemical solution is appropriately set according to the use and type of the chemical solution. For example, when the chemical solution is an aqueous TMAH solution used as a developer, its target concentration is set to 2.380 wt% or the like.

[0021] In addition to the acid component and the alkali component, the chemical solution may contain known additives such as nonionic surfactants and fluorine-based surfactants.

[0022] FIG. 1 shows a schematic configuration diagram of one form of the concentration adjustment device for the chemical solution of the present invention. In FIG. 1, the concentration adjustment device 10 is a device that mixes a stock solution containing an arbitrary component and pure water to adjust a chemical solution having a predetermined concentration, specifically, a device that adjusts the concentration of a developer. The concentration adjustment device 10 includes an adjustment tank 1 having a tank body 2, a stock solution supply device 4 that supplies the stock solution to the tank body 2, a pure water supply device 5 that supplies pure water to the tank body 2, a measuring device 6, and a control device 7.

[0023] The tank body 2 in the adjustment tank 1 has a supply port formed, for example, at the upper part, and the stock solution and pure water are supplied from this supply port. The tank body 2 is a tank that receives the stock solution and pure water and stores the mixed solution, and preferably has corrosion resistance. The capacity of the tank body 2 is not particularly limited, and is, for example, 100 L to 3000 L.

[0024] A circulation pipe 3 for circulating the mixed solution in the tank body 2 is provided in the adjustment tank 1. The circulation pipe 3 is provided, for example, so as to connect a discharge port at the lower part (bottom in FIG. 1) of the tank body 2 to a supply port that opens inside the tank body 2. A valve V21, a valve V22, a pump 8, a valve V23, and a measuring device 6 are provided in the circulation pipe 3. When the valves V21, V22, and V23 are opened and the valve V24 is closed, the pump 8 operates, so that the mixed solution in the tank body 2 is stirred while circulating through the circulation pipe 3. That is, the circulation pipe 3 via the pump 8 also functions as a stirring means for making the mixed solution have a uniform concentration. Therefore, known stirring means such as stirring blades for stirring the mixed solution inside the tank body 2 can be omitted.

[0025] The circulation pipe 3 is connected to the discharge pipe 9 at connection point C. Connection point C is located between the pump 8 and the valve V23. The chemical solution (developer in Figure 1), which has been adjusted to the target concentration threshold by the concentration adjustment device 10, is sent to the production device through the discharge pipe 9 via the operation of the pump 8 through the valve V24.

[0026] The concentrate supply device 4 has a concentrate storage tank and a plurality of supply pipes P01 and P02 connected to the storage tank. The concentrate used is, for example, an aqueous solution with a concentration of the above-mentioned components set to about 10 to 30 wt%, and commercially available concentrates of various concentrations are used. In the concentrate supply device 4, the diameters of the supply pipes P01 and P02 are different from each other, with P01 > P02. Valves V01 and V02 are provided on pipes P01 and P02, and the amount of concentrate supplied is adjusted by opening and closing valves V01 and V02. In this specification, valves refer to automatic on / off valves that can be opened and closed by electronic control, and the specific opening and closing mechanism is not particularly limited.

[0027] For the diameters of supply pipes P01 and P02, for example, the nominal diameter (the outer diameter dimension of the pipe according to JIS standards) can be used. In this nominal diameter, for example, pipes from 6A to 40A can be used. The same applies to supply pipes P11, P12, and P13, which will be described later.

[0028] The pure water supply system 5 has a pure water storage tank and a plurality of supply pipes P11, P12, and P13 connected to the storage tank. Ultrapure water separated and purified using ion exchange resin or the like can be used as pure water. The diameters of the supply pipes P11, P12, and P13 are different from each other, with the order of diameter being P11 > P12 > P13. Valves V11, V12, and V13 are provided on the pipes P11, P12, and P13, and the amount of pure water supplied is adjusted by opening and closing the valves V11, V12, and V13.

[0029] For supplying the concentrate and pure water in the concentrate supply device 4 and the pure water supply device 5, methods such as using a pump or pressurizing with a gas such as air or N2 can be employed. In configurations where multiple supply pipes are provided in each of the supply devices 4 and 5 as shown in Figure 1, supplying by pressurizing with gas is preferred. Pure water may be supplied directly from a pure water production facility.

[0030] Furthermore, by providing multiple supply pipes of different diameters in each supply device 4 and 5, the supply time can be shortened while allowing for fine adjustment of the supply amount, making it easier to adjust the concentration accurately. Note that the number of supply pipes provided in each supply device 4 and 5 is not limited to two or three, but may be one or four or more. For example, in a configuration in which the concentration is adjusted by dilution with pure water, it is preferable to have more supply pipes in the pure water supply device 5 than in the stock solution supply device 4, considering the need to fine-tune the concentration by adjusting the amount of pure water supplied. This further simplifies the device configuration.

[0031] The measuring device 6 is a device that measures the conductivity and liquid temperature of the mixed liquid introduced from the tank body 2 into the circulation piping 3 to obtain the concentration values ​​of the components. The measuring device 6 is composed of, for example, a conductivity detector and a temperature detector, and the concentration value is obtained from the conductivity and liquid temperature measured by the conductivity detector and temperature detector, respectively, using a conversion formula that is determined separately. This conversion formula is a formula that converts the measured conductivity to concentration while correcting for temperature, and can be obtained from a known conversion formula or from separate prior experiments. A commercially available device can be used for the measuring device 6. The concentration value obtained by the measuring device 6 is input to the control device 7.

[0032] The control device 7 consists of a PLC (Programmable Logic Controller) and a PC (Personal Computer). The control device 7 is connected to the measuring device 6 and each valve to send and receive signals, and controls various calculations and valve opening times. The control device 7 has pre-stored information on the relationship between the opening times of valves V01, V02, V11, V12, and V13, which are installed in each supply pipe P01, P02, P11, P12, and P13, and the flow rate of the fluid passing through the corresponding supply pipe. It also stores information such as the target concentration of the chemical solution and predetermined threshold values ​​for the target concentration. As a result, by controlling the opening time of each valve, the amount of liquid supplied from each supply pipe, such as the stock solution or pure water, can be adjusted.

[0033] By controlling the opening time of each valve in this way, the liquid volume can be adjusted, eliminating the need to install metering pumps or other devices in each supply pipe, thus contributing to a simplified system configuration and cost reduction.

[0034] The control device 7 first compares the concentration value obtained by the measuring device 6 with a predetermined threshold value for the target concentration. The predetermined threshold value for the target concentration is set appropriately depending on the application and type of the chemical solution; for example, in the case of a TMAH aqueous solution, it is set to a threshold value of 2.380 ± 0.001 wt%. If the obtained concentration value is outside the predetermined threshold value, the control device calculates the amount of stock solution or pure water (additional liquid) required to bring the obtained concentration value to the median concentration between the obtained concentration value and the target concentration. Then, it opens the valves of the supply pipes of the stock solution supply device 4 or the pure water supply device 5 and supplies the calculated additional amount of stock solution or pure water to the tank body 2. By repeating this process, the concentration is eventually brought closer to the target concentration.

[0035] It should be noted that the concentration adjustment device of the present invention is not limited to the configuration of the concentration adjustment device 10 shown in Figure 1, and can be modified as appropriate. In addition, temperature control means such as a heating unit for adjusting the temperature to a predetermined temperature may be provided in the adjustment tank 1 or circulation piping 3 of the concentration adjustment device 10, but the concentration value obtained by the measuring device 6 takes into account the liquid temperature of the mixed liquid, so there is no need to adjust the temperature of the mixed liquid, and therefore temperature control means may not be provided.

[0036] Next, the concentration adjustment method of the present invention will be described. This method involves mixing a stock solution containing any component with pure water to prepare a chemical solution of a predetermined concentration. As shown in Figure 2, the concentration adjustment method of the present invention comprises (A) an initial supply step, (B) a concentration measurement step, and (C) an adjustment step. The (C) adjustment step includes (C1) an additional liquid volume calculation step and (C2) an additional supply step. Each step will be described below with appropriate reference to the apparatus in Figure 1.

[0037] [Process (A)] This process involves mixing a predetermined amount of stock solution with pure water to obtain a mixture with a predetermined concentration within a set range of the target concentration. The predetermined range of the target concentration in process (A) is set, for example, to a range of 50% to 200% of the target concentration. For example, if the target concentration of the chemical solution is 2.380 wt%, the concentration is set to a range of 1.190 wt% to 4.76 wt%. Note that this concentration is different from the target concentration.

[0038] In the embodiment where concentration adjustment is performed by dilution with pure water, the concentration may be set to a range of 101% to 200% of the target concentration, a range of 101% to 150% of the target concentration, or a range of 101% to 120% of the target concentration. On the other hand, in the embodiment where concentration adjustment is performed by increasing the concentration with the stock solution, the concentration may be set to a range of 50% to 99% of the target concentration, a range of 75% to 99% of the target concentration, or a range of 90% to 99% of the target concentration.

[0039] In process (A), the method of supplying the stock solution or pure water is not particularly limited and can be supplied to the adjustment tank through supply piping. For example, in the concentration adjustment device 10 of Figure 1, the stock solution or pure water can be supplied to the tank body 2 through multiple supply pipes P01, P02, P11, P12, and P13. In this case, the amount of stock solution or pure water is controlled by adjusting the opening time of valves V01, V02, V11, V12, and V13 provided in the supply pipes P01, P02, P11, P12, and P13. In process (A), precise liquid volume adjustment is not necessary, and the supply may be carried out using the supply pipes P01 and P11 with the largest diameter in each supply device 4 and 5.

[0040] In process (A), valves V21, V22, V23, and V24 are closed when supplying the stock solution or pure water.

[0041] [Process (B)] This process involves stirring the mixture obtained in process (A) for a predetermined time (e.g., 3 to 10 minutes), and then measuring the conductivity and temperature of the mixture within the system to obtain a concentration value. For example, in the concentration adjustment device 10 shown in Figure 1, the mixture in the adjustment tank 1 is stirred by circulating it through the circulation pipe 3. Specifically, with valve V24 closed, valves V21, V22, and V23 are opened, and the pump 8 is operated to circulate the mixture, which is then stirred by the circulating flow. The flow rate (circulation flow rate) passing through the circulation pipe 3 is adjusted by the output of the pump 8.

[0042] For example, the stirring efficiency of process (B) performed after process (A) may be made greater than the stirring efficiency of process (B) performed after process (C). In this case, for example, the circulation flow rate of process (B) performed after process (A) may be made relatively larger, or the time for circulating the mixture (corresponding to the stirring time) may be made relatively longer.

[0043] After circulating the mixed liquid for a predetermined time, the conductivity and temperature of the mixed liquid introduced into the circulation pipe 3 are measured. The concentration value of the mixed liquid is then obtained using a separately determined conversion formula. Note that the concentration value obtained in the initial concentration measurement (initial concentration) is not aimed at being within the threshold of the target concentration, and in the flowchart of Figure 2, the concentration determination step S11 that follows process (B) is rejected (step S11; No), and the process proceeds to process (C).

[0044] [Process (C)] In this step, first, the amount of stock solution or pure water required to reach the median concentration between the concentration value obtained in step (B) and the target concentration is calculated (step (C1)). This median concentration is determined from the obtained concentration value and the target concentration. For example, if the obtained concentration value is 2.4557 wt% and the target concentration is 2.380 wt%, the median concentration will be 2.4179 (= (2.4557 + 2.380) / 2) wt%). This median concentration is set as the first provisional target concentration, and the amount of pure water required to reach that provisional target concentration is calculated.

[0045] Then, the calculated amount of pure water is supplied to the mixture (step (C2)). For example, in the concentration adjustment device 10 of Figure 1, one or more supply pipes P11, P12, and P13 are selected according to the required amount of pure water, and the valves provided in the selected supply pipes are opened for a time corresponding to the required amount of pure water. This brings the concentration of the mixture in the tank body 2 closer to the first provisional target concentration.

[0046] As shown in Figure 2, after step (C2), step (B) is performed again. That is, the mixture is stirred for a predetermined time (e.g., 3 to 10 minutes), and the conductivity and temperature of the mixture are measured within the system to obtain the concentration value again.

[0047] The concentration is then determined again using the obtained concentration value (step S11 in Figure 2). If the obtained concentration value (in this case, the concentration value after the first additional supply) is not within the threshold of the target concentration, the process (C1) is repeated. In the second process (C1), for example, if the obtained concentration value is 2.4124 wt% and the target concentration is 2.380 wt%, the median concentration will be 2.3962 (= (2.4124 + 2.380) / 2) wt%). This median concentration is set as the second provisional target concentration, and the amount of pure water required to reach that provisional target concentration is calculated.

[0048] Then, the calculated amount of pure water is supplied to the mixture (step (C2)), and step (B) is performed again, leading to the concentration determination step. In this way, steps (B) and (C) are repeated until the concentration value obtained in step (B) falls within the predetermined range of the target concentration. Finally, when the concentration determination step is confirmed, this concentration adjustment method is completed, and a chemical solution adjusted to the predetermined concentration is obtained.

[0049] Figure 3 shows an example of the concentration progression of a mixed solution using the concentration adjustment method of the present invention. As shown in Figure 3, by repeatedly performing steps (B) and (C) described above, the concentration gradually approaches the target concentration from the initial concentration, and finally falls within the threshold range of the target concentration. Thus, with the above method, strict control of temperature and input amounts is not necessary, and even with fewer control items, the concentration can be reliably asymptotically converged to the target concentration. In addition, in the example in Figure 3, the chemical solution is produced by adding pure water six times in step (C), but even if the concentration increases or decreases beyond the target concentration, the concentration can be reliably asymptotically converged to the target concentration by appropriately adding pure water or the stock solution.

[0050] As shown in Figure 3, by setting the median concentration between the concentration value obtained each time and the target concentration as the provisional target concentration for the next time and repeating this process, the concentration of the mixed solution can be brought closer to the target concentration from one side. In the example in Figure 3, the concentration of the mixed solution approaches the target concentration from the higher concentration side, and in the additional supply in process (C), basically only pure water is supplied. For example, in this configuration, the pure water supply device can be configured to have greater precision in the supply amount, while the stock solution supply device can have a relatively simple configuration, and as a result, the overall efficiency of the device configuration can be improved. For example, the number of supply pipes for the pure water supply device, which requires fine adjustment of the supply amount, may be greater than the number of supply pipes for the stock solution supply device.

[0051] Furthermore, in concentration adjustment, the method is not limited to approaching the target concentration from the high-concentration side of the mixture; it may also be approached from the low-concentration side. In that case, the additional supply in process (C) basically only supplies the stock solution. For example, in this configuration, the stock solution supply device can be configured to have greater precision in the supply amount, and the pure water supply device can be configured to be relatively simple, resulting in improved overall efficiency of the system configuration.

[0052] The concentration adjustment method of the present invention has been described above, but it is not limited to the configuration described above. [Examples]

[0053] The concentration adjustment method was carried out under the following conditions using the concentration adjustment device shown in Figure 1. Furthermore, for the concentration measurement of the mixed solution, the concentration value was converted within the measuring device using separately determined temperature and concentration coefficients. [Test conditions] ·Stock concentration: TMAH (25.0±0.1wt%) • Target concentration and threshold: 2.380 ± 0.001 wt% • Target adjustment time: within 60 minutes • Method of supplying undiluted solution and pure water: Gas pressure transfer • Tank size: 250L • Agitation method: A circulation method in which the water is drawn out from the bottom of the tank using a pump and circulated. 55 L / min (only during stirring in the first step (B) after the initial supply) 25 L / min • Concentration measurement method: Yokogawa Electric electromagnetic conductivity detector (ISC40GJ) Liquid analyzer (FLXA402) • Supply piping (nominal diameter) For pure water: 1 inch (25A) 1 / 2 inch (15A) 1 / 4 inch (8A) For undiluted solution: 1 / 2 inch (15A) 1 / 4 inch (8A)

[0054] In Example 1, the initial supply process (step (A)) was set so that the concentration of the mixed solution was higher than the target concentration, and the initial concentration of the mixed solution was 2.4557 wt% (approximately 103% of the target concentration). In Example 2, the initial supply process (step (A)) was set so that the concentration of the mixed solution was lower than the target concentration, and the initial concentration of the mixed solution was 2.3509 wt% (approximately 99%). Subsequently, steps (B) and (C) described above were repeated until the target concentration was reached. The results are shown in Table 1 and Figure 4.

[0055] [Table 1]

[0056] Table 1 shows the initial concentrations for Examples 1-2, along with the additional supply amount, concentration value, and provisional target concentration for each additional supply step. Figure 4 shows the concentration progression for Examples 1-2. As shown in Table 1 and Figure 4, it was possible to asymptotically approach the target concentration from the initial concentration, whether starting from the high-concentration side or the low-concentration side, and to reliably converge to the target concentration. In Example 1, only pure water was supplied as an additional supply, and in Example 2, only the stock solution was supplied as an additional supply, allowing the concentration to reach the threshold value in both cases. Furthermore, by supplying the stock solution and pure water using multiple supply pipes in combination, rapid and accurate supply was achieved, allowing the adjustment to be completed within the target adjustment time, and the concentration adjustment was completed without taking a long time. [Industrial applicability]

[0057] The method and apparatus for adjusting the concentration of chemical solutions according to the present invention can be widely used for adjusting the concentration of chemical solutions such as developers, because it requires fewer control items, does not take a long time to adjust, and can perform high-precision concentration adjustment. [Explanation of Symbols]

[0058] 1 Adjustment tank 2 Tank body 3 Circulation piping 4 Stock solution supply device 5 Pure water supply device 6. Measuring device 7 Control device 8 pumps 9 Discharge piping 10 Concentration adjustment device P01, P02, P11, P12, P13 supply piping V01, V02, V11, V12, V13, V21, V22, V23, V24 valves C connection point

Claims

1. A method for adjusting the concentration of a chemical solution to a predetermined concentration by mixing a stock solution containing any component with pure water, (A) A step of mixing a predetermined amount of stock solution with pure water to obtain a mixed solution with a concentration ranging from 50% to 200% of a predetermined target concentration, (B) A step of stirring the obtained mixture for a predetermined time, measuring the conductivity and temperature of the mixture within the system to obtain a concentration value, (C) A step of calculating the amount of stock solution or pure water required to obtain the midpoint between the concentration value obtained in step (B) and the target concentration, and supplying the calculated amount of stock solution or pure water to the mixture, A method for adjusting the concentration of a drug solution, characterized by repeating steps (B) and (C) until the obtained concentration value falls within a predetermined range of a pre-set target concentration.

2. The method for adjusting the concentration of a chemical solution according to claim 1, wherein step (C) is a step of supplying a stock solution or pure water through a plurality of supply pipes having at least two or more different diameters, and the amount of stock solution or pure water is adjusted by controlling the opening time of valves provided in the supply pipes.

3. The method for adjusting the concentration of a chemical solution according to claim 1 or 2, characterized in that step (B) is a step of circulating and stirring the mixed liquid in the tank body through a circulation pipe in an adjustment tank, and measuring the conductivity and liquid temperature of the mixed liquid introduced into the circulation pipe to obtain a concentration value.

4. A concentration adjustment device that mixes a stock solution containing any component with pure water to prepare a chemical solution of a predetermined concentration, The device includes a regulating tank having a tank body, a stock solution supply device that supplies stock solution to the tank body through a plurality of supply pipes having at least two or more different diameters and equipped with valves, a pure water supply device that supplies pure water to the tank body through a plurality of supply pipes having at least two or more different diameters and equipped with valves, a measuring device that measures the conductivity and liquid temperature of the mixed liquid in the regulating tank to obtain a concentration value, and a control device that controls the opening time of the valves. The control device compares the concentration value obtained by the measuring device with a predetermined threshold value for the target concentration, and if the obtained concentration value is outside the predetermined threshold value, calculates the amount of stock solution or pure water required to bring the concentration to the median between the obtained concentration value and the target concentration, activates the valve, and supplies the calculated amount of stock solution or pure water to the tank body, thereby providing a chemical solution concentration adjustment device.

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