SUBSTRATE PROCESSING APPARATUS AND SUBSTRATE PROCESSING METHOD

Abstract

To appropriately perform etching processing with an etching solution containing an aqueous phosphoric acid solution and a silicon solution.SOLUTION: A board processing device according to an embodiment of the present disclosure includes a processing tank, a mixing device, a liquid supply path, and a control unit. In the processing tank, the board is immersed in a processing liquid for processing. The mixing device mixes a phosphoric acid aqueous solution and an additive to generate a mixed liquid which is a raw material of the processing liquid. The liquid supply path sends the mixed liquid from the mixing device to the processing tank. The control unit controls each component, and sends a mixing liquid having second concentration higher than first concentration when the phosphoric acid concentration is supplied to the mixing device, from the mixing device to the processing tank in which the board is immersed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The disclosed embodiments relate to a substrate processing apparatus and a substrate processing method. [Background technology]

[0002] Conventionally, in a substrate processing system, it is known to perform an etching process on a substrate by immersing the substrate in an etching solution containing an aqueous phosphoric acid solution and an additive that suppresses the deposition of silicon oxide (SiO2) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-118092 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for appropriately carrying out an etching treatment using an etching solution containing an aqueous phosphoric acid solution and a precipitation inhibitor. [Means for solving the problem]

[0005] A substrate processing apparatus according to an embodiment of the present disclosure includes a processing tank, a mixing device, a liquid transfer path, and a control unit. The processing tank processes a substrate by immersing it in a processing liquid. The mixing device mixes an aqueous phosphoric acid solution with an additive to generate a mixed liquid that is a raw material for the processing liquid. The liquid transfer path transfers the mixed liquid from the mixing device to the processing tank. The control unit controls each unit. In addition, the control unit transfers the mixed liquid, in which the phosphoric acid concentration in the mixing device has become a second concentration higher than a first concentration when supplied to the mixing device, from the mixing device to the processing tank in which the substrate is immersed. Effect of the Invention

[0006] According to the present disclosure, an etching process can be appropriately carried out using an etching solution containing an aqueous phosphoric acid solution and a precipitation inhibitor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic block diagram showing a configuration of a substrate processing system according to an embodiment. [Diagram 2] FIG. 2 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system in various processes when a mixed liquid is initially delivered to the processing tank according to the embodiment. [Diagram 3] FIG. 3 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system in various processes when a mixed liquid is initially delivered to the processing tank according to the embodiment. [Figure 4] FIG. 4 is a timing chart showing specific examples of behavior patterns of each part of the substrate processing system in various processes when adjusting the silicon concentration of the etching liquid in the processing tank according to this embodiment. [Diagram 5] FIG. 5 is a diagram for explaining details of the process of replacing the etching liquid in the processing tank according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining details of the process of replacing the etching liquid in the processing tank according to the embodiment. [Figure 7] FIG. 7 is a diagram for explaining details of the process of replacing the etching liquid in the processing tank according to the embodiment. [Figure 8] FIG. 8 is a schematic block diagram showing a configuration of a substrate processing system according to a first modified example of the embodiment. [Figure 9] FIG. 9 is a diagram showing a specific example of a process flow of each unit of the substrate processing system according to the first modification of the embodiment. [Figure 10] FIG. 10 is a schematic block diagram showing a configuration of a substrate processing system according to the second modification of the embodiment. [Figure 11] FIG. 11 is a diagram showing a specific example of a process flow of each unit of the substrate processing system according to the second modification of the embodiment. [Figure 12] FIG. 12 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system in various processes when the mixed liquid is initially delivered to the processing tank according to the third modification of the embodiment. [Figure 13] FIG. 13 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system during processing for maintaining the temperature and concentration of the mixed liquid in the processing tank according to the third modification of the embodiment. [Figure 14] FIG. 14 is a flowchart showing a procedure for substrate processing according to the embodiment. [Figure 15] FIG. 15 is a flowchart showing a procedure for substrate processing according to the third modification of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the attached drawings, an embodiment of the substrate processing apparatus and substrate processing method disclosed in the present application will be described in detail. Note that the present disclosure is not limited to the following embodiment. It should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may differ from reality. Furthermore, there may be parts in which the dimensional relationship and ratio differ between the drawings.

[0009] 2. Description of the Related Art Conventionally, in a substrate processing system, it is known to etch a substrate by immersing the substrate in an etching solution containing an aqueous phosphoric acid solution and an additive that suppresses deposition of silicon oxide.

[0010] For example, by immersing a substrate in an aqueous solution of phosphoric acid (H3PO4), it is possible to selectively etch the silicon nitride film out of the silicon nitride film (SiN) and silicon oxide film (SiO2) laminated on the substrate.

[0011] Furthermore, by adding an additive (hereinafter also referred to as a "precipitation inhibitor") that suppresses the precipitation of silicon oxide to the phosphoric acid aqueous solution, it is possible to suppress the precipitation of silicon oxide on the silicon oxide film during the etching process.

[0012] However, the above-mentioned conventional techniques leave room for further improvement in terms of appropriately etching a substrate.

[0013] Therefore, there is a need for a technique that overcomes the above-mentioned problems and enables etching treatment using an etching solution containing an aqueous phosphoric acid solution and a precipitation inhibitor to be properly carried out.

[0014] <Configuration of the substrate processing system> First, a configuration of a substrate processing system 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic block diagram showing a configuration of a substrate processing system 1 according to an embodiment. The substrate processing system 1 is an example of a substrate processing apparatus.

[0015] The substrate processing system 1 includes a mixer 10, a silicon solution supply unit 25, and a substrate processing unit 30. The mixer 10 mixes an aqueous phosphoric acid solution with a precipitation inhibitor that inhibits precipitation of silicon oxide to generate a mixed solution M. The precipitation inhibitor is an example of an additive.

[0016] The silicon solution supply unit 25 supplies a silicon-containing compound aqueous solution (hereinafter also referred to as a silicon solution) to the mixed solution M generated by the mixer 10 to generate an etching solution E. That is, the etching solution E according to the embodiment contains a phosphoric acid aqueous solution, a precipitation inhibitor, and a silicon solution. The etching solution E is an example of a processing solution.

[0017] The substrate processing unit 30 immerses the wafer W in the generated etching solution E in a processing tank 31, and performs an etching process on the wafer W. The wafer W is an example of a substrate. In the embodiment, for example, of a silicon nitride film (SiN) and a silicon oxide film (SiO2) formed on the wafer W, the silicon nitride film can be selectively etched.

[0018] The substrate processing system 1 also includes a control device 2. The control device 2 is, for example, a computer, and includes a control unit 3 and a storage unit 4. The storage unit 4 stores programs for controlling various processes executed in the substrate processing system 1. The control unit 3 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the storage unit 4.

[0019] Such a program may be recorded in a computer-readable storage medium and installed from that storage medium into the storage unit 4 of the control device 2. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

[0020] The mixer 10 includes an aqueous phosphoric acid solution supply section 11 , a precipitation inhibitor supply section 12 , a tank 14 , and a circulation path 15 .

[0021] The aqueous phosphoric acid solution supply unit 11 supplies an aqueous phosphoric acid solution to the tank 14. The aqueous phosphoric acid solution supply unit 11 includes an aqueous phosphoric acid solution supply source 11a, an aqueous phosphoric acid solution supply path 11b, and a flow rate regulator 11c.

[0022] The aqueous phosphoric acid solution supply source 11a is, for example, a tank that stores an aqueous phosphoric acid solution. The aqueous phosphoric acid solution supply path 11b connects the aqueous phosphoric acid solution supply source 11a and the tank 14, and supplies the aqueous phosphoric acid solution from the aqueous phosphoric acid solution supply source 11a to the tank 14.

[0023] The flow rate regulator 11c is provided in the phosphoric acid aqueous solution supply path 11b, and regulates the flow rate of the phosphoric acid aqueous solution supplied to the tank 14. The flow rate regulator 11c is composed of an on-off valve, a flow rate control valve, a flow meter, and the like.

[0024] The precipitation inhibitor supplying unit 12 supplies the precipitation inhibitor to the tank 14. The precipitation inhibitor supplying unit 12 includes a precipitation inhibitor supply source 12a, a precipitation inhibitor supply path 12b, and a flow rate regulator 12c.

[0025] The deposition inhibitor supply source 12a is, for example, a tank that stores the deposition inhibitor. The deposition inhibitor supply path 12b connects the deposition inhibitor supply source 12a and the tank 14 and supplies the deposition inhibitor from the deposition inhibitor supply source 12a to the tank 14.

[0026] The flow rate regulator 12c is provided in the deposition inhibitor supply path 12b, and regulates the flow rate of the deposition inhibitor supplied to the tank 14. The flow rate regulator 12c is composed of an on-off valve, a flow control valve, a flow meter, and the like.

[0027] The precipitation inhibitor according to the embodiment may contain a component that inhibits the precipitation of silicon oxide. For example, the precipitation inhibitor may contain a component that stabilizes silicon ions dissolved in the phosphoric acid aqueous solution in a dissolved state to inhibit the precipitation of silicon oxide. The precipitation inhibitor may also contain a component that inhibits the precipitation of silicon oxide by other known methods.

[0028] The deposition inhibitor according to the embodiment may be, for example, an aqueous solution of hexafluorosilicic acid (H2SiF6) containing a fluorine component. In addition, in order to stabilize the hexafluorosilicic acid in the aqueous solution, an additive such as ammonia may be included.

[0029] As the precipitation inhibitor according to the embodiment, for example, ammonium hexafluorosilicate (NH4)2SiF6, sodium hexafluorosilicate (Na2SiF6), or the like can be used.

[0030] Furthermore, the precipitation inhibitor according to the embodiment may be a compound containing an element that is a cation with an ionic radius of 0.2 Å to 0.9 Å. Here, the "ionic radius" refers to the radius of an ion empirically determined from the sum of the radii of an anion and a cation obtained from the lattice constant of a crystal lattice.

[0031] The precipitation inhibitor according to the embodiment may contain, for example, an oxide of any of the elements aluminum, potassium, lithium, sodium, magnesium, calcium, zirconium, tungsten, titanium, molybdenum, hafnium, nickel, and chromium.

[0032] Furthermore, the precipitation inhibitor according to the embodiment may contain at least one of a nitride, a chloride, a bromide, a hydroxide, and a nitrate of any of the above elements, instead of or in addition to an oxide of any of the above elements.

[0033] The precipitation inhibitor according to the embodiment may include, for example, at least one of Al(OH)3, AlCl3, AlBr3, Al(NO3)3, Al2(SO4)3, AlPO4, and Al2O3.

[0034] The precipitation inhibitor according to the embodiment may include at least one of KCl, KBr, KOH, and KNO3. Furthermore, the precipitation inhibitor according to the embodiment may include at least one of LiCl, NaCl, MgCl2, CaCl2, and ZrCl4.

[0035] The tank 14 stores the phosphoric acid aqueous solution supplied from the phosphoric acid aqueous solution supply unit 11 and the precipitation inhibitor supplied from the precipitation inhibitor supply unit 12. The tank 14 also stores a mixed liquid M produced by mixing the phosphoric acid aqueous solution and the precipitation inhibitor.

[0036] A first liquid level sensor S1 and a second liquid level sensor S2 are provided in the tank 14 in this order from the top. This controls the liquid levels of the phosphoric acid aqueous solution and the mixed liquid M stored in the tank 14. Furthermore, in the embodiment, the first liquid level sensor S1 and the second liquid level sensor S2 are used to measure the liquid amounts of the phosphoric acid aqueous solution and the precipitation inhibitor.

[0037] The circulation path 15 is a circulation line that exits from the tank 14 and returns to the tank 14. The circulation path 15 has an inlet provided at the bottom of the tank 14 and an outlet provided at the top of the tank 14, and forms a circulation flow that flows from the inlet to the outlet. In the embodiment, the outlet is disposed above the liquid level of the mixed liquid M stored in the tank 14.

[0038] In the circulation path 15, a first pump 16, a filter 18, a first heater 19, a phosphoric acid concentration sensor 52, a branching portion 15a, a branching portion 15b, and a valve 20 are provided in this order from the upstream side with respect to the tank 14. The first heater 19 is an example of a heating mechanism.

[0039] The first pump 16 creates a circulation flow of the mixed liquid M that leaves the tank 14 , passes through the circulation path 15 , and returns to the tank 14 .

[0040] The filter 18 removes contaminants such as particles contained in the mixed liquid M circulating in the circulation path 15. The circulation path 15 is provided with a bypass flow path 21 that bypasses the filter 18, and the bypass flow path 21 is provided with an opening / closing valve 21a.

[0041] By opening and closing the on-off valve 21a provided in the bypass flow path 21, it is possible to form either a circulation flow that flows through the filter 18 or a circulation flow that bypasses the filter 18. This is because the pressure loss of the filter 18 is relatively large, and therefore when the on-off valve 21a is opened, a circulation flow that flows through the filter 18 is not formed.

[0042] The first heater 19 heats the mixed liquid M circulating in the circulation path 15. In the embodiment, the mixed liquid M stored in the tank 14 is heated by heating the mixed liquid M with the first heater 19.

[0043] The phosphoric acid concentration sensor 52 detects the phosphoric acid concentration of the mixed liquid M circulating through the circulation path 15. A signal generated by the phosphoric acid concentration sensor 52 is transmitted to the control unit 3 described above.

[0044] From the branching portion 15a and the branching portion 15b, liquid transport paths 22 for transporting the mixed liquid M to the processing tank 31 of the substrate processing portion 30 branch off. Specifically, a first liquid transport path 22a for transporting the mixed liquid M to the inner tank 31a of the processing tank 31 branches off from the branching portion 15a, and a second liquid transport path 22b for transporting the mixed liquid M to the outer tank 31b of the processing tank 31 branches off from the branching portion 15b. That is, the liquid transport path 22 has a first liquid transport path 22a and a second liquid transport path 22b.

[0045] A first flow rate regulator 23a is provided in the first liquid transport path 22a. The first flow rate regulator 23a regulates the flow rate of the mixed liquid M supplied to the inner tank 31a of the treatment tank 31. The first flow rate regulator 23a is composed of an on-off valve, a flow rate control valve, a flow meter, etc.

[0046] In the second liquid transfer path 22b, a second flow regulator 23b, a branching portion 22b1, a thermometer 53, a flowmeter 55, a constant pressure valve 56, a throttle valve 57, a branching portion 22b2, and a valve 58 are provided in this order from the upstream side.

[0047] The second flow rate regulator 23b regulates the flow rate of the mixed liquid M supplied to the outer bath 31b of the treatment bath 31. The second flow rate regulator 23b is composed of an on-off valve, a flow rate control valve, a flow meter, and the like.

[0048] A first return path 24a for returning the mixed liquid M to the tank 14 branches off from the branching portion 22b1. The first return path 24a has a back pressure valve 54. The back pressure valve 54 adjusts the pressure on the upstream side of the back pressure valve 54 in the first return path 24a (for example, the branching portion 22b1).

[0049] The thermometer 53 measures the temperature of the mixed liquid M flowing through the second liquid transfer path 22b. The flowmeter 55 measures the flow rate of the mixed liquid M flowing through the second liquid transfer path 22b. The flowmeter 55 corrects the flow rate of the mixed liquid M based on the temperature of the mixed liquid M measured by the thermometer 52. For example, the control unit 3 corrects the flow rate information of the mixed liquid M obtained from the flowmeter 55 based on the temperature information of the mixed liquid M obtained from the thermometer 52.

[0050] As a result, in this embodiment, even if the temperature of the mixed liquid M changes significantly within a range from room temperature to a high temperature, the flow rate of the mixed liquid M flowing through the flowmeter 55 can be measured with high accuracy.

[0051] The constant pressure valve 56 adjusts the pressure in the second liquid transfer path 22b downstream of the constant pressure valve 56. The throttle valve 57 adjusts the flow rate of the mixed liquid M flowing through the second liquid transfer path 22b.

[0052] A second return path 24b that returns the mixed liquid M to the tank 14 branches off from the branching portion 22b2. In this manner, in the embodiment, the return path 24 composed of the first return path 24a and the second return path 24b branches off from the second liquid supply path 22b, and the return path 24 returns the mixed liquid M flowing through the second liquid supply path 22b to the tank 14. The second return path 24b has a valve 59.

[0053] The control unit 3 alternately opens and closes the valve 58 and the valve 59. In this way, the control unit 3 can switch between sending the mixed liquid M to the outer tank 31b or the tank 14.

[0054] The silicon solution supply unit 25 adds a silicon solution to the mixed liquid M generated by the mixer 10. The silicon solution according to the embodiment is, for example, a solution in which colloidal silicon is dispersed. The silicon solution supply unit 25 includes a silicon solution supply source 25a, a silicon solution supply path 25b, and a flow rate regulator 25c.

[0055] The silicon solution supply source 25a is, for example, a tank that stores the silicon solution. The flow rate regulator 25c is provided in the silicon solution supply path 25b and regulates the flow rate of the silicon solution flowing through the silicon solution supply path 25b. The silicon solution supply path 25b is connected to the outer bath 31b of the processing bath 31. The flow rate regulator 25c is composed of an on-off valve, a flow rate control valve, a flow meter, etc.

[0056] The substrate processing unit 30 immerses the wafer W in the etching liquid E generated in the mixing device 10, and performs an etching process on the wafer W.

[0057] The substrate processing section 30 includes a processing tank 31, a circulation path 32, a DIW supply section 33, and a processing liquid discharge section 34. The processing tank 31 has an inner tank 31a and an outer tank 31b.

[0058] The inner tank 31a has an open top, and the etching solution E is supplied up to near the top. In the inner tank 31a, a plurality of wafers W are immersed in the etching solution E by a substrate lifting mechanism 35, and the wafers W are etched. The substrate lifting mechanism 35 is configured to be capable of lifting and lowering, and holds the plurality of wafers W aligned in a vertical position, one behind the other.

[0059] The outer tank 31b is provided around the upper portion of the inner tank 31a and has an open upper portion. The etching solution E that overflows from the inner tank 31a flows into the outer tank 31b.

[0060] A third liquid level sensor S3 is provided in the outer tank 31b. This controls the liquid levels of the mixed liquid M and the etching liquid E stored in the outer tank 31b. Furthermore, in the embodiment, the third liquid level sensor S3 is used to measure the amount of the mixed liquid M. The details of the measurement process of the mixed liquid M will be described later.

[0061] The mixed liquid M is supplied to the inner tank 31a and the outer tank 31b from the mixer 10 via the liquid supply path 22. The silicon solution is supplied to the inner tank 31a from the silicon solution supply unit 25. The outer tank 31b is supplied with DIW (DeIonized Water) from the DIW supply unit 33.

[0062] The DIW supply unit 33 includes a DIW supply source 33a, a DIW supply path 33b, and a flow rate regulator 33c. The DIW supply unit 33 supplies DIW to the outer bath 31b in order to adjust the concentration of the etching liquid E stored in the processing bath 31.

[0063] The DIW supply path 33b connects the DIW supply source 33a and the outer bath 31b, and supplies DIW at a predetermined temperature from the DIW supply source 33a to the outer bath 31b.

[0064] The flow rate regulator 33c is provided in the DIW supply path 33b and regulates the amount of DIW supplied to the outer bath 31b. The flow rate regulator 33c is composed of an on-off valve, a flow control valve, a flow meter, etc. The amount of DIW supplied is adjusted by the flow rate regulator 33c, whereby the temperature, phosphoric acid concentration, silicon concentration, and precipitation inhibitor concentration of the etching solution E are adjusted.

[0065] Further, the outer tank 31b is provided with a temperature sensor 36 and a phosphoric acid concentration sensor 37. The temperature sensor 36 detects the temperature of the etching solution E, and the phosphoric acid concentration sensor 37 detects the phosphoric acid concentration of the etching solution E. Signals generated by the temperature sensor 36 and the phosphoric acid concentration sensor 37 are transmitted to the control unit 3 described above.

[0066] The outer bath 31b and the inner bath 31a are connected by a circulation path 32. One end of the circulation path 32 is connected to the bottom of the outer bath 31b, and the other end of the circulation path 32 is connected to a processing liquid supply nozzle 38 installed in the inner bath 31a.

[0067] In the circulation path 32, a second pump 39, a filter 40, a second heater 41, and a silicon concentration sensor 42 are provided in this order from the outer bath 31b side.

[0068] The second pump 39 forms a circulating flow of the etching solution E that is sent from the outer bath 31b to the inner bath 31a via the circulation path 32. Moreover, the etching solution E overflows from the inner bath 31a and flows back into the outer bath 31b. In this way, a circulating flow of the etching solution E is formed in the substrate processing unit 30. That is, the circulating flow is formed in the outer bath 31b, the circulation path 32, and the inner bath 31a.

[0069] The filter 40 filters the etching solution E circulating through the circulation path 32. The second heater 41 adjusts the temperature of the etching solution E circulating through the circulation path 32. The silicon concentration sensor 42 detects the silicon concentration of the etching solution E circulating through the circulation path 32. A signal generated by the silicon concentration sensor 42 is transmitted to the control unit 3.

[0070] The processing liquid discharge unit 34 discharges the liquid surface of the mixed liquid M or the etching liquid E to the drain DR when replacing the mixed liquid M stored when generating the etching liquid E or all or a part of the etching liquid E used in the etching process. The processing liquid discharge unit 34 has a discharge path 34a, a flow rate regulator 34b, and a cooling tank 34c.

[0071] The discharge path 34a is connected to the circulation path 32. The flow rate regulator 34b is provided in the discharge path 34a, and regulates the discharge rates of the discharged mixed liquid M and etching liquid E. The flow rate regulator 34b is composed of an on-off valve, a flow control valve, a flow meter, and the like.

[0072] The cooling tank 34c temporarily stores and cools the mixed liquid M and the etching liquid E that have flowed through the discharge path 34a. In the cooling tank 34c, the discharge rates of the mixed liquid M and the etching liquid E are adjusted by the flow rate adjuster 34b.

[0073] <Substrate processing procedure> Next, a procedure for substrate processing according to the embodiment will be described with reference to Fig. 2 to Fig. 7. Fig. 2 and Fig. 3 are timing charts showing specific examples of behavior patterns of each part of the substrate processing system 1 in various processes when the mixed liquid M is initially delivered to the processing tank 31 according to the embodiment.

[0074] Note that Figure 2 shows the first half of the various processes when the mixed liquid M is delivered to the processing tank 31 for the first time, and Figure 3 shows the second half of the various processes when the mixed liquid M is delivered to the processing tank 31 for the first time.

[0075] 2 and 3, in the embodiment, the mixing process, the concentration adjustment process, the filtration process, the liquid delivery process, and the addition process are performed in this order. First, the control unit 3 operates (turns on) the phosphoric acid aqueous solution supply unit 11 from time T0 to supply the phosphoric acid aqueous solution to the tank 14, thereby starting the mixing process.

[0076] At time T0, the deposition inhibitor supply unit 12, the first pump 16, and the first heater 19 are not operating (OFF state). Also, at time T0, the on-off valve 21a is in an open state, so the filter 18 is bypassed by the bypass flow path 21 (filter bypass is ON state).

[0077] Furthermore, at time T0, the first flow regulator 23a and the second flow regulator 23b are in a closed state (OFF state), and nothing is stored in the tank 14, so that an OFF signal is output from the first liquid level sensor S1 and the second liquid level sensor S2.

[0078] Then, at time T1 when a predetermined amount of the phosphoric acid aqueous solution has been supplied to the tank 14, the control unit 3 operates the first pump 16 (turns it on) to form a circulating flow in the circulation path 15.

[0079] Next, the liquid level of the phosphoric acid aqueous solution stored in the tank 14 gradually rises, and when the liquid level reaches or exceeds a predetermined second height at time T2, an ON signal is output from the second liquid level sensor S2. Then, the control unit 3 operates (switches to ON state) the precipitation inhibitor supply unit 12 from time T2 to supply the precipitation inhibitor to the tank 14, and stops (switches to OFF state) the phosphoric acid aqueous solution supply unit 11.

[0080] Next, at time T3 when a predetermined amount of precipitation inhibitor has been supplied to tank 14, control unit 3 stops precipitation inhibitor supply unit 12 (switches it to OFF state) and operates phosphoric acid aqueous solution supply unit 11 (switches it to ON state) to supply phosphoric acid aqueous solution to tank 14.

[0081] Next, when the liquid level of the mixed liquid M reaches or exceeds a predetermined first height at time T4, an ON signal is output from the first liquid level sensor S1. Then, the control unit 3 determines that a predetermined amount of the aqueous phosphoric acid solution has been supplied to the tank 14, and stops (sets to the OFF state) the aqueous phosphoric acid solution supply unit 11 at time T4.

[0082] This completes the mixing process, and a mixed solution M having a first phosphoric acid concentration is generated in the mixer 10. The first concentration is, for example, about 80 (mass %).

[0083] In this manner, the control unit 3 operates the first pump 16 before supplying the precipitation inhibitor to the tank 14. This makes it possible to form a circulating flow in the circulation path 15 before the precipitation inhibitor is supplied, thereby improving the mixability of the phosphoric acid aqueous solution and the precipitation inhibitor.

[0084] Furthermore, the control unit 3 does not supply the phosphoric acid aqueous solution and the precipitation inhibitor to the tank 14 at the same time, but supplies them separately to the tank 14. This makes it possible to prevent the first liquid level sensor S1 from outputting an ON signal before a predetermined amount of the precipitation inhibitor is supplied. Therefore, according to the embodiment, it is possible to reliably supply a predetermined amount of the precipitation inhibitor to the tank 14.

[0085] Next, the control unit 3 starts the concentration adjustment process by operating (turning on) the first heater 19 from time T4 to heat the mixed liquid M circulating in the circulation path 15. The control unit 3 heats the mixed liquid M stored in the tank 14 by heating the mixed liquid M with the first heater 19.

[0086] As a result, the control unit 3 evaporates the mixed liquid M in the mixing device 10, and adjusts the phosphoric acid concentration of the mixed liquid M from the first concentration to the third concentration. That is, the third concentration is higher than the first concentration.

[0087] This third concentration is, for example, about 90 (mass %). Then, at time T5 when the phosphoric acid concentration of the mixed liquid M reaches the third concentration, the concentration adjustment process is completed.

[0088] In this manner, in the embodiment, by providing the first heater 19 in the circulation path 15 of the mixer 10, the mixed liquid M can be efficiently heated, and therefore the concentration of the mixed liquid M can be efficiently adjusted.

[0089] In the substrate processing according to the embodiment, the concentration adjustment process (heating process) is started after the mixing process is completed. This is because if the precipitation inhibitor containing an organic solvent is supplied to the heated phosphoric acid aqueous solution, the precipitation inhibitor may bump.

[0090] That is, according to the embodiment, by starting the concentration adjustment process (heating process) after the mixing process is completed, it is possible to prevent the precipitation inhibitor from bumping during supply.

[0091] Next, the control unit 3 starts the filtration process by turning off the filter bypass from time T5. That is, the control unit 3 changes the on-off valve 21a to a closed state from time T5 to form a circulation flow in the circulation path 15 that flows through the filter 18.

[0092] This removes contaminants such as particles contained in the mixed liquid M. Then, at time T6 when contaminants such as particles contained in the mixed liquid M have been sufficiently removed, the filtration process is completed.

[0093] At time T6 when the filtration process is completed, the control unit 3 stops the first heater 19 (turns it to the OFF state). This makes it possible to prevent the phosphoric acid concentration of the mixed liquid M in the mixing device 10 from becoming higher than the third concentration.

[0094] In the substrate processing according to the embodiment, the filter bypass is turned on in the mixing process and the concentration adjustment process. This reduces the pressure loss caused by the filter 18 in the circulation path 15, and therefore the mixed liquid M stored in the tank 14 can be circulated efficiently.

[0095] Since there is no need to filter the mixed liquid M with the filter 18 until the concentration adjustment process is completed, there is no problem even if the mixed liquid M is circulated through the bypass flow path 21.

[0096] Next, the control unit 3 starts the liquid transfer process from time T6. Specifically, the control unit 3 opens the first flow regulator 23a (turns it to the ON state) from time T6. The second flow regulator 23b maintains its closed state. Although not shown in FIG. 2, the control unit 3 changes the valve 20 of the circulation path 15 from the open state to the closed state at time T6.

[0097] As a result, the control unit 3 sends the mixed liquid M from the mixer 10 to the inner tank 31a of the substrate processing unit 30 through the circulation path 15 and the first liquid sending path 22a. Also, the control unit 3 operates (turns on) an agitation mechanism (e.g., a bubbling mechanism, not shown in FIG. 1) provided in the inner tank 31a from time T6, as shown in FIG. 3.

[0098] Then, when the liquid supply process to the processing tank 31 is started and the mixed liquid M in the outer tank 31b increases, the liquid level of the mixed liquid M stored in the outer tank 31b becomes equal to or higher than the predetermined third height at time T7. This causes the third liquid level sensor S3 to output an ON signal.

[0099] Next, at time T8 when a predetermined amount of mixed liquid M has been supplied to the treatment tank 31, the first pump 16 is stopped (turned OFF) and the first flow rate regulator 23a is closed (turned OFF). This stops the supply of mixed liquid M to the treatment tank 31 and completes the liquid transfer process. The control unit 3 also turns the filter bypass ON at time T8.

[0100] Next, the control unit 3 starts the process of adding the silicon solution from time T8. First, the control unit 3 operates the second pump 39 and the second heater 41 of the circulation path 32 (turns them on) from time T8.

[0101] In this manner, by circulating and heating the mixed liquid M in the circulation path 32, the control unit 3 adjusts the temperature and phosphoric acid concentration of the mixed liquid M in the treatment tank 31 to predetermined values.

[0102] Next, at time T9 when the temperature and phosphoric acid concentration of the mixed solution M in the treatment tank 31 reach predetermined values ​​(temperature and concentration sensor: ON), the control unit 3 stops (turns off) the stirring mechanism of the treatment tank 31. In this way, the control unit 3 stabilizes the liquid level of the mixed solution M stored in the inner tank 31a.

[0103] Next, when a predetermined time has elapsed from time T9, at time T10 when the liquid level of the mixed liquid M stored in the inner tank 31a has stabilized, the control unit 3 operates (turns on) the treatment liquid discharge unit 34. As a result, the control unit 3 lowers the liquid level of the mixed liquid M stored in the outer tank 31b.

[0104] Next, at time T11 when the liquid level of the mixed liquid M stored in the outer tank 31b becomes lower than a predetermined third height and an OFF signal is output from the third liquid level sensor S3, the control unit 3 stops the treatment liquid discharge unit 34 (sets it to the OFF state).

[0105] Here, since the liquid level of the mixed liquid M in the outer tank 31b is approximately equal to a predetermined third height and the inner tank 31a is filled with the mixed liquid M, the control unit 3 can weigh out a predetermined amount of the mixed liquid M stored in the entire processing tank 31. Therefore, according to the embodiment, the amount of the mixed liquid M when the etching liquid E is produced can be accurately adjusted.

[0106] Next, at time T11 when a predetermined amount of mixed liquid M has been supplied to the processing tank 31, the control unit 3 operates (turns ON) the silicon solution supply unit 25 and also operates (turns ON) the stirring mechanism of the processing tank 31. As a result, the control unit 3 sends the silicon solution to the inner tank 31a of the substrate processing unit 30 via the silicon solution supply path 25b.

[0107] Then, as the amount of liquid in the outer tank 31b increases, the liquid level of the mixed liquid M stored in the outer tank 31b reaches or exceeds a predetermined third height at time T12, causing the third liquid level sensor S3 to output an ON signal.

[0108] Next, at time T13 when a predetermined amount of silicon solution has been delivered, the control unit 3 stops (turns off) the silicon solution supply unit 25. Furthermore, the control unit 3 operates the stirring mechanism of the processing tank 31 until time T14, which is a predetermined time after time T13, and the silicon solution addition process is completed.

[0109] By the process described above, the control unit 3 can prepare the etching solution E having a desired silicon concentration in the processing tank 31 when the mixed solution M is initially sent to the processing tank 31. Therefore, according to the embodiment, the etching selectivity of the silicon nitride film to the silicon oxide film can be improved from the start of the etching process for the wafer W.

[0110] Moreover, in the embodiment, by etching the wafer W with the etching solution E having a third concentration in which the phosphoric acid concentration is high, the silicon nitride film can be selectively etched efficiently.

[0111] In the embodiment, the control unit 3 supplies both the mixed liquid M and the silicon solution to the inner tank 31a of the processing tank 31. As a result, in the embodiment, the mixed liquid M and the silicon solution can be mixed while overflowing from the inner tank 31a to the outer tank 31b, thereby improving the mixability of the mixed liquid M and the silicon solution.

[0112] FIG. 4 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system 1 in various processes when adjusting the silicon concentration of the etching liquid E in the processing tank 31 according to this embodiment.

[0113] 4, an etching process for a wafer W is started in the processing tank 31, and preparation and liquid delivery process of a mixed liquid M that is delivered when silicon is eluted from the wafer W into the etching liquid E will be described.

[0114] First, the control unit 3 operates (turns on) the aqueous phosphoric acid solution supply unit 11 from time T20 to supply the aqueous phosphoric acid solution to the tank 14, thereby starting the mixing process.

[0115] At the time T20, the precipitation inhibitor supply unit 12, the silicon solution supply unit 25, the first pump 16, and the first heater 19 are not operating (they are in the OFF state). Also, at the time T20, the filter 18 is bypassed by the bypass flow path 21 (the filter bypass is in the ON state), and the back pressure valve 54 is in the fully open state.

[0116] Furthermore, at time T20, the first flow regulator 23a and the second flow regulator 23b are in a closed state (OFF state), and nothing is stored in the tank 14, so that an OFF signal is output from the first liquid level sensor S1 and the second liquid level sensor S2.

[0117] Then, at time T21 when a predetermined amount of the phosphoric acid aqueous solution has been supplied to the tank 14, the control unit 3 operates the first pump 16 (turns it on) to form a circulating flow in the circulation path 15.

[0118] Next, the liquid level of the phosphoric acid aqueous solution stored in the tank 14 gradually rises, and when the liquid level reaches or exceeds a predetermined second height at time T22, an ON signal is output from the second liquid level sensor S2. Then, the control unit 3 operates (sets to ON state) the precipitation inhibitor supply unit 12 from time T22 to supply the precipitation inhibitor to the tank 14, and stops (sets to OFF state) the phosphoric acid aqueous solution supply unit 11.

[0119] Next, at time T23 when a predetermined amount of precipitation inhibitor has been supplied to tank 14, control unit 3 stops precipitation inhibitor supply unit 12 (switches it to OFF state) and operates phosphoric acid aqueous solution supply unit 11 (switches it to ON state) to supply phosphoric acid aqueous solution to tank 14.

[0120] Next, when the liquid level of the mixed liquid M reaches or exceeds a predetermined first height at time T24, an ON signal is output from the first liquid level sensor S1. Then, the control unit 3 determines that a predetermined amount of the aqueous phosphoric acid solution has been supplied to the tank 14, and stops (sets to the OFF state) the aqueous phosphoric acid solution supply unit 11 at time T24.

[0121] This completes the mixing process, and a mixed liquid M having a phosphoric acid concentration of the first concentration is produced in the mixer 10.

[0122] Next, the control unit 3 starts the concentration adjustment process by operating (turning on) the first heater 19 from time T24 to heat the mixed liquid M circulating in the circulation path 15. The control unit 3 heats the mixed liquid M stored in the tank 14 by heating the mixed liquid M with the first heater 19.

[0123] As a result, the control unit 3 evaporates the mixed liquid M in the mixing device 10, and adjusts the phosphoric acid concentration of the mixed liquid M from the first concentration to the second concentration. That is, the second concentration is higher than the first concentration.

[0124] The second concentration is lower than the third concentration, and is, for example, about 85 (mass%). The concentration adjustment process is completed at time T25 when the phosphoric acid concentration of the mixed solution M becomes the second concentration.

[0125] Next, the control unit 3 starts the filtration process by turning off the filter bypass from time T25, thereby removing contaminants such as particles contained in the mixed liquid M. Then, at time T26 when the contaminants such as particles contained in the mixed liquid M have been sufficiently removed, the filtration process is completed.

[0126] Next, the control unit 3 starts the liquid transfer process from time T26. Specifically, the control unit 3 opens the second flow regulator 23b (turns it to the ON state) from time T6, and turns the back pressure valve 54 to the throttling state. The first flow regulator 23a maintains the closed state. Although not shown in FIG. 4, the control unit 3 also changes the valve 20 of the circulation path 15 from the open state to the closed state at time T26.

[0127] As a result, the control unit 3 sends the mixed liquid M from the mixer 10 to the outer tank 31b of the substrate processing unit 30 via the circulation path 15 and the second liquid sending path 22b. Then, the mixed liquid M in the tank 14 decreases, and the liquid level becomes lower than the predetermined first height at time T27. As a result, an OFF signal is output from the first liquid level sensor S1.

[0128] In this embodiment, the control unit 3 performs control based on the silicon concentration of the etching solution E in the processing tank 31 obtained from the silicon concentration sensor 42 to always keep the silicon concentration in the processing tank 31 constant or below a constant value.

[0129] For example, when the silicon concentration of the etching solution E in the processing tank 31 becomes higher than a given threshold value, the control unit 3 opens the flow regulator 34b to discharge the etching solution E with a high silicon concentration and supplies the same amount of mixed liquid M as the discharged etching solution E.

[0130] In the embodiment, since the mixing process of the mixed liquid M is completed in the mixer 10, the mixed liquid M not containing the silicon solution can be supplied to the processing tank 31 when necessary.

[0131] Thereby, the control unit 3 can keep the amount of the etching solution E stored in the processing tank 31 constant, and can reduce the silicon concentration of the etching solution E in the processing tank 31. Therefore, according to the embodiment, the silicon concentration in the processing tank 31 can be always kept constant or below a certain level.

[0132] In the embodiment, the control unit 3 can supply the mixed liquid M that does not contain a silicon solution to the processing tank 31. This makes it possible to quickly suppress the silicon concentration of the etching solution E to a predetermined concentration when silicon is eluted from the silicon nitride film in the wafer W and the silicon concentration of the etching solution E becomes excessive.

[0133] In addition, in the embodiment, by separately supplying a silicon solution to the generated mixed liquid M to generate the etching liquid E, the silicon concentration of the mixed liquid M supplied to the substrate processing unit 30 can be adjusted over a wide range.

[0134] That is, when a predetermined silicon concentration is required in the mixed liquid M (for example, at the time of the initial liquid transfer), the mixed liquid M containing the silicon solution can be supplied to the processing tank 31 by operating the silicon solution supply unit 25.

[0135] On the other hand, when a specified silicon concentration is not required in the mixed liquid M (for example, when adjusting the silicon concentration), the silicon solution supply unit 25 is not operated, so that the mixed liquid M that does not contain silicon solution can be supplied to the processing tank 31.

[0136] Furthermore, in the embodiment, the mixed liquid M used for adjusting the silicon concentration of the etching liquid E is adjusted to a second concentration higher than the first concentration by the above-mentioned concentration adjustment process. This makes it possible to prevent the phosphoric acid concentration of the etching liquid E from decreasing significantly from the third concentration, compared to the case where the silicon concentration of the etching liquid E is adjusted using the mixed liquid M in which the phosphoric acid concentration remains at the first concentration.

[0137] That is, in the embodiment, the phosphoric acid concentration of the etching solution E can be more stabilized, so that the etching process of the wafer W with the etching solution E can be appropriately performed.

[0138] In the embodiment, the mixed liquid M used to adjust the silicon concentration of the etching liquid E is adjusted to a second concentration lower than the third concentration by the above-mentioned concentration adjustment process. This makes it possible to shorten the time for the concentration adjustment process, and therefore makes it possible to efficiently prepare the mixed liquid M used to adjust the silicon concentration of the etching liquid E.

[0139] In the embodiment, the mixed liquid M used to adjust the silicon concentration of the etching liquid E is sent through a second liquid sending path 22b different from the first liquid sending path 22a. This makes it possible to adjust the silicon concentration of the etching liquid E without using the mixed liquid M having the third phosphoric acid concentration remaining in the first liquid sending path 22a.

[0140] Therefore, according to the embodiment, the phosphoric acid concentration of the etching solution E can be more stabilized, so that the etching process of the wafer W with the etching solution E can be more appropriately performed.

[0141] In the embodiment, when adjusting the silicon concentration of the etching solution E, the adjustment process is performed while detecting the phosphoric acid concentration of the mixed solution M being fed by the phosphoric acid concentration sensor 52 of the circulation path 15. That is, in the embodiment, the phosphoric acid concentration sensor 52 feedback-controls the amount of the mixed solution M being fed.

[0142] This makes it possible to further stabilize the phosphoric acid concentration in the etching solution E, so that the etching process of the wafer W using the etching solution E can be performed more appropriately.

[0143] In the embodiment, when the supply of the mixed liquid M to the treatment tank 31 is not required, the control unit 3 may return the mixed liquid M flowing through the second liquid transfer path 22b to the tank 14 through the second return path 24b.

[0144] That is, when the supply of mixed liquid M to the treatment tank 31 is not required, the control unit 3 changes the valve 58 to a closed state and the valve 59 to an open state, and circulates the mixed liquid M using the circulation path 15, the second liquid supply path 22b and the second return path 24b.

[0145] This makes it possible to uniform a state in which the mixed liquid M is ejected from the second liquid delivery path 22b to the outer tank 31b (i.e., a state in which the supply of the mixed liquid M is necessary) and a state in which the mixed liquid M is not ejected from the second liquid delivery path 22b to the outer tank 31b (i.e., a state in which the supply of the mixed liquid M is not necessary).

[0146] Therefore, according to the embodiment, since the mixed liquid M can be discharged with higher accuracy, the process of always keeping the silicon concentration in the processing tank 31 constant or below a certain level can be performed with higher accuracy.

[0147] In the embodiment, the mixed liquid M flowing through the second liquid feed path 22b may be returned to the tank 14 from the first return path 24a in addition to the second return path 24b.

[0148] This makes it possible to increase the flow rate of the mixed liquid M flowing through the second liquid transfer path 22b, thereby ensuring the minimum flow rate of the mixed liquid M required when heating the mixed liquid M with the first heater 19. Therefore, according to the embodiment, the mixed liquid M can be stably heated.

[0149] In the embodiment, the control unit 3 may throttle the back pressure valve 54 during the liquid transfer process of the mixed liquid M. This allows the control unit 3 to increase the pressure at the branch point 22b1 in the second liquid transfer path 22b, thereby ensuring the pressure required to return the mixed liquid M to the tank 14 from the branch point 22b1 via the second liquid transfer path 22b and the second return path 24b.

[0150] In the embodiment, when adjusting the flow rate of the mixed liquid M discharged from the second liquid delivery path 22b to the outer tank 31b, the flow rate is roughly adjusted using the throttle valve 57, and the flow rate is finely adjusted using the flow meter 55 and the constant pressure valve 56.

[0151] In this embodiment, the flow rate of the mixed liquid M in the flow meter 55 may be kept constant by feedback-controlling the pressure of the mixed liquid M in the flow meter 55 with the constant pressure valve 56. This allows a more accurate amount of the mixed liquid M to be discharged, and therefore allows a more accurate process of keeping the silicon concentration in the processing tank 31 always constant or below a certain level.

[0152] In addition, in the embodiment, the control unit 3 may supply the mixed liquid M to the outer tank 31b instead of the inner tank 31a when adjusting the silicon concentration of the etching liquid E. This makes it possible to suppress a sudden change in the silicon concentration of the etching liquid E in the inner tank 31a, compared to the case where the mixed liquid M is directly supplied to the inner tank 31a in which the wafer W is being processed.

[0153] Therefore, according to the embodiment, the etching process of the wafer W can be performed more stably.

[0154] In the embodiment, the liquid transport path 22 (first liquid transport path 22a and second liquid transport path 22b) is provided branching off from the circulation path 15. This allows the mixed liquid M to be transported to the treatment tank 31 by the first pump 16 used in the mixing process and the concentration adjustment process.

[0155] That is, in the embodiment, since it is not necessary to provide a separate pump in the liquid transfer path 22 for the liquid transfer process of the mixed liquid M, the mixed liquid M can be transferred at low cost.

[0156] 5 to 7 are diagrams for explaining the details of the process of replacing the etching liquid E in the processing tank 31 according to the embodiment. Among these, Fig. 5 is a diagram showing the state immediately before replacing the etching liquid E in the processing tank 31.

[0157] 5, the treatment tank 31 according to the embodiment has a fourth liquid level sensor S4 and a fifth liquid level sensor S5 in addition to the third liquid level sensor S3 described above. The fourth liquid level sensor S4 is provided in the outer tank 31b, and the fifth liquid level sensor S5 is provided in the inner tank 31a.

[0158] This controls the liquid levels of the mixed liquid M and the etching liquid E stored in the outer tank 31b and the inner tank 31a. The fourth liquid level sensor S4 is provided near the bottom of the outer tank 31b, which is lower than the third liquid level sensor S3. The fifth liquid level sensor S5 is provided near the bottom of the inner tank 31a.

[0159] Furthermore, the bottom of the inner tank 31a is connected to a drain DR via a drain valve 70, and the bottom of the outer tank 31b is connected to a drain DR via a drain valve 71. The control unit 3 can drain the mixed liquid M and the etching liquid E stored in the inner tank 31a and the outer tank 31b by opening the drain valves 70 and 71.

[0160] As shown in FIG. 5, immediately before replacing the etching liquid E in the processing tank 31, both exhaust valves 70, 71 are in a closed state (indicated as "C" in FIG. 5), and the amount of etching liquid E required for processing the wafer W (see FIG. 1) is stored in the inner tank 31a and the outer tank 31b.

[0161] In the process of replacing the etching solution E in the processing tank 31 according to the embodiment, the control unit 3 first changes the drain valve 71 from a closed state to an open state (indicated as "O" in FIG. 6) as shown in FIG.

[0162] Then, the liquid level of the etching liquid E stored in the outer tank 31b gradually drops, and when the liquid level becomes lower than a predetermined fourth height near the bottom, an OFF signal is output from the fourth liquid level sensor S4.

[0163] Then, when an OFF signal is output from the fourth liquid level sensor S4, the control unit 3 changes the drain valve 71 from an open state to a closed state, thereby enabling the control unit 3 to keep the amount of etching solution E remaining in the outer tank 31b at a constant value.

[0164] Next, the control unit 3 changes the drain valve 70 from the closed state to the open state, as shown in Fig. 7. Then, the liquid level of the etching liquid E stored in the inner tank 31a gradually drops, and when the liquid level becomes lower than a predetermined fifth height near the bottom, an OFF signal is output from the fifth liquid level sensor S5.

[0165] When the fifth liquid level sensor S5 outputs an OFF signal, the control unit 3 changes the drain valve 70 from an open state to a closed state, thereby enabling the control unit 3 to keep the amount of etching solution E remaining in the inner tank 31a at a constant value.

[0166] Then, the control unit 3 performs the liquid sending process and the addition process shown in FIGS. 2 and 3 on the processing tank 31 in which the etching liquid E remains as shown in FIG.

[0167] Here, if an attempt is made to drain all of the etching liquid E without leaving a certain amount of etching liquid E in the inner tank 31a and the outer tank 31b, there is a risk that the amount of etching liquid E that is not drained and remains in the piping, pumps, etc. will vary.

[0168] 2 and 3 are performed on the processing tank 31 in which the amount of remaining etching solution E varies, the amount of silicon remaining in the processing tank 31 varies, so the silicon concentration of the newly generated etching solution E also varies. Therefore, in this case, it is difficult to appropriately perform the etching process of the wafer W with the etching solution E.

[0169] However, in the embodiment, the amount of etching solution E remaining in the processing tank 31 can be kept constant by the processing shown in Figures 5 to 7, and therefore the amount of silicon remaining in the processing tank 31 can be kept constant.

[0170] That is, in the embodiment, it is possible to set the silicon concentration of the newly generated etching solution E to a desired value. Therefore, according to the embodiment, the etching process of the wafer W using the etching solution E can be more appropriately performed.

[0171] In the example of Figures 5 to 7, the etching liquid E in the outer tank 31b is first discharged, and then the etching liquid E in the inner tank 31a is discharged. However, the order in which the etching liquid E is discharged from the processing tank 31 is not limited to this example.

[0172] For example, the etching solution E in the inner tank 31a may be discharged first, and then the etching solution E in the outer tank 31b may be discharged, or the etching solutions E in the inner tank 31a and the outer tank 31b may be discharged in parallel.

[0173] <Variation 1> Next, various modified examples of the substrate processing system 1 according to the embodiment will be described with reference to Fig. 8 to Fig. 11. Fig. 8 is a schematic block diagram showing the configuration of the substrate processing system 1 according to Modification 1 of the embodiment. In the following various modified examples, the same components as those in the embodiment are denoted by the same reference numerals, and redundant description will be omitted.

[0174] In the substrate processing system 1 according to the first modification, a plurality of mixers 10 (see FIG. 1) are provided for one processing tank 31. In the example of FIG. 8, two mixers 10A and 10B are provided for one processing tank 31. In the following description, the plurality of mixers 10A and 10B are also collectively referred to as "mixer 10."

[0175] A liquid transfer path 22A is connected between the mixer 10A and the treatment tank 31, and the mixed liquid M is transferred from the mixer 10A to the treatment tank 31 via the liquid transfer path 22A. The mixed liquid M is returned to the tank 14 (see FIG. 1) of the mixer 10A via a return path 24A connected to the liquid transfer path 22A.

[0176] A liquid transfer path 22B is connected between the mixer 10B and the treatment tank 31, and the mixed liquid M is transferred from the mixer 10B to the treatment tank 31 through the liquid transfer path 22B. The mixed liquid M is returned to the tank 14 of the mixer 10B through a return path 24B connected to the liquid transfer path 22B.

[0177] In addition, in variant example 1, each of the liquid delivery paths 22A and 22B has the first liquid delivery path 22a and the second liquid delivery path 22b shown in FIG. 1, and each of the return paths 24A and 24B has the first return path 24a and the second return path 24b shown in FIG. 1.

[0178] Further, a silicon solution supply unit 25 is connected to the treatment tank 31 , and a silicon solution is supplied to the treatment tank 31 via the silicon solution supply unit 25 .

[0179] FIG. 9 is a diagram showing a specific example of a process flow of each unit of the substrate processing system 1 according to the first modification of the embodiment.

[0180] As shown in Fig. 9, the control unit 3 (see Fig. 1) first performs the mixing process (referred to as "mixing" in the following drawings) shown in Fig. 2, the concentration adjustment process (referred to as "concentration" in the following drawings), and the filtration process (not shown in Fig. 9) in that order in the mixing device 10A. In this way, the control unit 3 prepares a mixed solution M having a third phosphoric acid concentration in the mixing device 10A.

[0181] Next, the control unit 3 sends the mixed solution M having a third phosphoric acid concentration from the mixing device 10A to the treatment tank 31 (referred to as "sending" in the following drawings). Then, when the sending process of the mixed solution M from the mixing device 10A is completed, the control unit 3 supplies the silicon solution from the silicon solution supply unit 25 to the treatment tank 31, and performs the adding process of the silicon solution shown in FIG. 3 (referred to as "adding" in the following drawings).

[0182] Through the various treatments described above, the etching solution E having the third phosphoric acid concentration and the desired silicon concentration is prepared in the treatment tank 31.

[0183] In parallel with various processes in the mixing device 10A and the silicon solution supplying unit 25, the control unit 3 sequentially performs the mixing process, the concentration adjustment process, and the filtration process (not shown) shown in Fig. 4 in the mixing device 10B. In this way, the control unit 3 prepares the mixed solution M having a second phosphoric acid concentration in the mixing device 10B.

[0184] Next, the control unit 3 immerses the wafer W in the processing tank 31 and performs an etching process on the wafer W. In this etching process, the control unit 3 also performs a process (hereinafter also referred to as a "silicon adjustment process") of always keeping the silicon concentration in the processing tank 31 constant or below a constant level by sending mixed liquid M having a second phosphoric acid concentration from the mixing device 10B.

[0185] In parallel with the liquid delivery process of the mixing device 10B, the control unit 3 sequentially performs the mixing process, concentration adjustment process, and filtration process (not shown) shown in Fig. 4 in the mixing device 10A that has once completed the liquid delivery process. In this way, the control unit 3 prepares a mixed liquid M having a second phosphoric acid concentration in the mixing device 10A.

[0186] Then, when the mixed liquid M in the mixing device 10B is depleted and the liquid delivery process of the mixing device 10B is completed, the control unit 3 continues the silicon adjustment process in the treatment tank 31 by delivering the mixed liquid M having a second phosphoric acid concentration from the mixing device 10A.

[0187] In parallel with the liquid sending process of the mixer 10A, the control unit 3 sequentially performs the mixing process, the concentration adjustment process, and the filtration process (not shown) shown in Fig. 4 in the mixer 10B. In this way, the control unit 3 prepares the mixed liquid M having a second phosphoric acid concentration in the mixer 10B.

[0188] Then, when the mixed liquid M in the mixing device 10A is depleted and the liquid delivery process of the mixing device 10A is completed, the control unit 3 continues the silicon adjustment process in the treatment tank 31 by delivering the mixed liquid M having a second phosphoric acid concentration from the mixing device 10B.

[0189] As described above, in the first modified example, the mixed liquid M is sequentially delivered from one of the multiple mixing devices 10 to one processing tank 31 in which the etching process is performed, and the remaining mixing devices 10 prepare the mixed liquid M having a second phosphoric acid concentration.

[0190] This allows the silicon preparation process to be continuously performed in one processing tank 31. Therefore, according to the first modification, the etching process of the wafer W with the etching liquid E in one processing tank 31 can be more appropriately performed.

[0191] In the first modification, an example in which two mixers 10 are provided for one treatment tank 31 has been shown, but the number of mixers 10 provided for one treatment tank 31 is not limited to two.

[0192] <Variation 2> 10 is a schematic block diagram showing a configuration of a substrate processing system 1 according to Modification 2 of the embodiment. In the substrate processing system 1 according to Modification 2, a plurality of mixers 10 (see FIG. 1) are provided for a plurality of processing tanks 31 (see FIG. 1).

[0193] 10, three mixers 10A-10C are provided for three treatment tanks 31A-31C. In the following description, the multiple mixers 10A-10C will also be collectively referred to as "mixer 10," and the multiple treatment tanks 31A-31C will also be collectively referred to as "treatment tank 31."

[0194] A liquid transfer path 22A branched into three paths is connected between the mixer 10A and the treatment tanks 31A to 31C, and the mixed liquid M is transferred from the mixer 10A to the treatment tanks 31A to 31C individually through the liquid transfer paths 22A.

[0195] Furthermore, the mixed liquid M is returned to the tank 14 (see FIG. 1) of the mixer 10A via the return path 24A which is connected to each of the three branched liquid sending paths 22A.

[0196] A liquid transfer path 22B branched into three paths is connected between the mixer 10B and the treatment tanks 31A to 31C, and the mixed liquid M is transferred from the mixer 10B to the treatment tanks 31A to 31C individually via the liquid transfer paths 22B.

[0197] Furthermore, the mixed liquid M is returned to the tank 14 of the mixer 10B via the return path 24B which is connected to each of the three branched liquid sending paths 22B.

[0198] A liquid transfer path 22C branched into three paths is connected between the mixer 10C and each of the treatment tanks 31A to 31C, and the mixed liquid M is transferred from the mixer 10C to each of the treatment tanks 31A to 31C via the liquid transfer paths 22C.

[0199] Furthermore, the mixed liquid M is returned to the tank 14 of the mixer 10C via a return path 24C that is connected to each of the three branched liquid sending paths 22C.

[0200] In addition, in the second modification, each of the liquid transport paths 22A to 22C has the first liquid transport path 22a and the second liquid transport path 22b shown in FIG. 1, and each of the return paths 24A to 24C has the first return path 24a and the second return path 24b shown in FIG.

[0201] Further, a silicon solution supply unit 25 is connected to each of the processing baths 31A to 31C, and a silicon solution is supplied to each of the processing baths 31A to 31C via the silicon solution supply unit 25 individually.

[0202] Furthermore, a buffer tank 11d is provided downstream of the aqueous phosphoric acid solution supply source 11a in the aqueous phosphoric acid solution supply unit 11 that supplies the aqueous phosphoric acid solution to the mixers 10A to 10C. In the second modification, by providing the buffer tank 11d, the aqueous phosphoric acid solution used in the multiple mixers 10A to 10C can be sufficiently supplied in the required amount at the required timing.

[0203] In the second modification, when the phosphoric acid aqueous solution supply unit 11 has a sufficient capacity to supply the phosphoric acid aqueous solution, the phosphoric acid aqueous solution supply unit 11 does not necessarily need to be provided with the buffer tank 11d.

[0204] FIG. 11 is a diagram showing a specific example of a process flow of each unit of the substrate processing system 1 according to the second modification of the embodiment.

[0205] As shown in Fig. 11, the control unit 3 (see Fig. 1) first performs the mixing process, the concentration adjustment process, and the filtration process (not shown in Fig. 11) shown in Fig. 2 in the mixing device 10A in this order. In this way, the control unit 3 prepares a mixed solution M having a third phosphoric acid concentration in the mixing device 10A.

[0206] Next, the control unit 3 sends the mixed solution M having a third phosphoric acid concentration from the mixing device 10A to the treatment tank 31A. Then, when the sending process of the mixed solution M from the mixing device 10A is completed, the control unit 3 supplies the silicon solution from the silicon solution supply unit 25 to the treatment tank 31A, and performs the adding process of the silicon solution shown in FIG.

[0207] Through the various processes described above, the etching solution E having the third phosphoric acid concentration and the desired silicon concentration is prepared in the processing tank 31A.

[0208] In parallel with various processes in the mixing device 10A and the silicon solution supplying unit 25, the control unit 3 sequentially performs the mixing process, the concentration adjustment process, and the filtration process (not shown in FIG. 11) shown in FIG. 2 in the mixing device 10B. In this way, the control unit 3 prepares the mixed solution M having a third phosphoric acid concentration in the mixing device 10B.

[0209] Next, the control unit 3 sends the mixed solution M having a third phosphoric acid concentration from the mixing device 10B to the treatment tank 31B. Then, when the sending process of the mixed solution M from the mixing device 10B is completed, the control unit 3 supplies the silicon solution from the silicon solution supply unit 25 to the treatment tank 31B, and performs the adding process of the silicon solution shown in FIG.

[0210] Through the various treatments described above, the etching solution E having the third phosphoric acid concentration and the desired silicon concentration is prepared in the treatment tank 31B.

[0211] In parallel with the various processes of the mixers 10A and 10B and the silicon solution supply unit 25, the control unit 3 sequentially performs the mixing process, concentration adjustment process, and filtration process (not shown in FIG. 11) shown in FIG. 2 in the mixer 10C. In this way, the control unit 3 prepares a mixed solution M having a third phosphoric acid concentration in the mixer 10C.

[0212] Next, the control unit 3 sends the mixed solution M having a third phosphoric acid concentration from the mixing device 10C to the treatment tank 31C. Then, when the sending process of the mixed solution M from the mixing device 10C is completed, the control unit 3 supplies the silicon solution from the silicon solution supply unit 25 to the treatment tank 31C, and performs the adding process of the silicon solution shown in FIG.

[0213] Through the various processes described above, the etching solution E having the third phosphoric acid concentration and the desired silicon concentration is prepared in the processing tank 31C.

[0214] In parallel with various processes in the mixers 10B and 10C and the silicon solution supply unit 25, the control unit 3 sequentially performs the mixing process, concentration adjustment process, and filtration process (not shown) shown in Fig. 4 in the mixer 10A that has once completed the liquid delivery process. In this way, the control unit 3 prepares a mixed solution M having a second phosphoric acid concentration in the mixer 10A.

[0215] Next, the control unit 3 sequentially immerses the wafers W in the processing tanks 31A to 31C and performs an etching process on the wafers W. In the etching process, the control unit 3 also performs a silicon adjustment process in the processing tanks 31A to 31C by sending the mixed liquid M having a second phosphoric acid concentration from the mixer 10A.

[0216] In parallel with the various processes of the mixers 10A and 10C and the silicon solution supply unit 25, the control unit 3 sequentially performs the mixing process, concentration adjustment process, and filtration process (not shown) shown in Fig. 4 in the mixer 10B, which has once completed the liquid delivery process. In this way, the control unit 3 prepares the mixed solution M having a second phosphoric acid concentration in the mixer 10B.

[0217] Then, when the mixed liquid M in the mixing device 10A is exhausted and the liquid delivery process of the mixing device 10A is completed, the control unit 3 continues the silicon adjustment process in the treatment tanks 31A to 31C by delivering the mixed liquid M having a second phosphoric acid concentration from the mixing device 10B.

[0218] In parallel with the various processes in the mixers 10A and 10B, the control unit 3 sequentially performs the mixing process, concentration adjustment process, and filtration process (not shown) shown in Fig. 4 in the mixer 10C, which has once completed the liquid delivery process. In this way, the control unit 3 prepares a mixed solution M having a second phosphoric acid concentration in the mixer 10C.

[0219] Then, when the mixed liquid M in the mixing device 10B is exhausted and the liquid supplying process of the mixing device 10B is completed, the control unit 3 continues the silicon adjustment process in the processing tanks 31A to 31C by supplying the mixed liquid M having a second phosphoric acid concentration from the mixing device 10C.

[0220] In parallel with the various processes in the mixers 10B and 10C, the control unit 3 sequentially performs the mixing process, concentration adjustment process, and filtration process (not shown) shown in Fig. 4 in the mixer 10A, which has once completed the liquid delivery process. In this way, the control unit 3 prepares a mixed solution M having a second phosphoric acid concentration in the mixer 10A.

[0221] Then, when the mixed liquid M in the mixing device 10C is exhausted and the liquid delivery process of the mixing device 10C is completed, the control unit 3 continues the silicon adjustment process in the treatment tanks 31A to 31C by delivering the mixed liquid M having a second phosphoric acid concentration from the mixing device 10A.

[0222] As described above, in the second modification, the mixed liquid M is sequentially delivered from one of the multiple mixing devices 10 to the multiple processing tanks 31 in which the etching process is performed, and the remaining mixing devices 10 prepare the mixed liquid M having a second phosphoric acid concentration.

[0223] This allows the silicon preparation process to be continuously performed in the multiple processing tanks 31. Therefore, according to the second modification, the etching process of the wafer W with the etchant E can be performed more appropriately in the multiple processing tanks 31.

[0224] Moreover, in the second modification, the etching process of the wafer W can be performed in parallel in the multiple processing tanks 31. Therefore, according to the second modification, the etching process of the wafer W using the etching liquid E can be performed efficiently.

[0225] In addition, in the second modification, an example in which three mixers 10 are provided for three treatment tanks 31 has been shown, but the number of treatment tanks 31 is not limited to three, and the number of mixers 10 is not limited to three.

[0226] <Variation 3> Fig. 12 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system 1 in various processes when the mixed liquid M is initially delivered to the processing tank 31 according to the third modified embodiment. Fig. 12 shows the first half of various processes when the mixed liquid M is initially delivered to the processing tank 31, and corresponds to Fig. 2 in the embodiment.

[0227] 12, in the modification 3, a phosphoric acid supply process, a concentration adjustment process, a filtration process, a mixing process, a liquid delivery process, and an addition process (not shown) are performed in this order. First, the control unit 3 operates (turns on) the phosphoric acid aqueous solution supply unit 11 from time T30 to supply the phosphoric acid aqueous solution to the tank 14, thereby starting the phosphoric acid supply process.

[0228] At the time T30, the deposition inhibitor supply unit 12, the first pump 16, and the first heater 19 are not operating (OFF state). Also, at the time T30, the on-off valve 21a is in an open state, so the filter 18 is bypassed by the bypass flow path 21 (filter bypass is ON state).

[0229] Also, at time T30, the first flow regulator 23a and the second flow regulator 23b are in a closed state (OFF state), and nothing is stored in the tank 14, so an OFF signal is output from the first liquid level sensor S1.

[0230] Furthermore, in this modification 3, a DIW supply unit (not shown) that supplies DIW to the tank 14, and a sixth liquid level sensor (not shown) that is provided at a predetermined height (hereinafter also referred to as the sixth height) higher than the first liquid level sensor S1 are provided. Also, in this modification 3, a level sensor (not shown) that measures the amount of the processing liquid stored in the tank 14 based on the head pressure at the bottom of the tank 14 is provided.

[0231] At time T30, the DIW supply unit is not operating (is in the OFF state), and nothing is stored in the tank 14, so that the sixth liquid level sensor and the level sensor output an OFF signal.

[0232] Then, at time T31 when a predetermined amount of the phosphoric acid aqueous solution has been supplied to the tank 14, the control unit 3 operates the first pump 16 (turns it on) to form a circulating flow in the circulation path 15.

[0233] Next, the liquid level of the aqueous phosphoric acid solution stored in the tank 14 gradually rises, and when the liquid level reaches or exceeds a predetermined first height at time T32, an ON signal is output from the first liquid level sensor S1.

[0234] Furthermore, when the liquid level of the phosphoric acid aqueous solution reaches or exceeds a sixth predetermined height at time T33, an ON signal is output from the sixth liquid level sensor. Then, the control unit 3 determines that a predetermined amount of phosphoric acid aqueous solution has been stored in the tank 14, and stops (sets to the OFF state) the phosphoric acid aqueous solution supply unit 11 at time T33. This completes the phosphoric acid supply process, and a predetermined amount of phosphoric acid aqueous solution is stored in the tank 14.

[0235] Next, the control unit 3 starts the concentration adjustment process by operating (turning on) the first heater 19 from time T33 to heat the phosphoric acid aqueous solution circulating in the circulation path 15. The control unit 3 heats the phosphoric acid aqueous solution stored in the tank 14 by heating the phosphoric acid aqueous solution with the first heater 19.

[0236] As a result, the control unit 3 evaporates the aqueous phosphoric acid solution in the mixer 10, and adjusts the phosphoric acid concentration of the aqueous phosphoric acid solution from the first concentration to the third concentration.

[0237] Then, the liquid level of the aqueous phosphoric acid solution stored in the tank 14 gradually decreases, and at time T34 when the liquid level becomes lower than a predetermined sixth level, an OFF signal is output from the sixth liquid level sensor.

[0238] Next, the control unit 3 starts the filtration process by turning off the filter bypass at time T35, which is a predetermined time (for example, 10 minutes) before time T37 at which the filtration process described below ends.

[0239] In addition, when the liquid level of the phosphoric acid aqueous solution stored in the tank 14 becomes lower than a predetermined first height and an OFF signal is output from the first liquid level sensor S1 at time T36, the control unit 3 operates the DIW supply unit (switches it to the ON state) to supply DIW to the tank 14.

[0240] Then, the control unit 3 stops (turns off) the DIW supply unit at time T37, which is a predetermined time (for example, 10 minutes) after time T35. This completes the concentration adjustment process and the filtration process, and an aqueous phosphoric acid solution having a phosphoric acid concentration of the third concentration is generated in the mixer 10.

[0241] Next, the control unit 3 starts the mixing process by operating (turning ON) the precipitation inhibitor supply unit 12 from time T37 to supply the precipitation inhibitor to the tank 14. Then, at time T37, the liquid level of the mixed liquid M becomes equal to or higher than a predetermined first height, and an ON signal is output from the first liquid level sensor S1.

[0242] On the other hand, since the first heater 19 continues to operate after time T37, the mixed liquid M in the mixing device 10 continues to evaporate, so that the mixed liquid M in the tank 14 becomes lower than the predetermined first height at time T38, and an OFF signal is output from the first liquid level sensor S1 at time T38.

[0243] Next, at time T39 when a predetermined amount of the precipitation inhibitor has been supplied to the tank 14, the control unit 3 stops (turns off) the precipitation inhibitor supply unit 12. As a result, the phosphoric acid concentration is adjusted to the third concentration, and mixed solution M in which the precipitation inhibitor is adjusted to a predetermined concentration is produced.

[0244] Then, the control unit 3 operates the level sensor using the head pressure at the bottom of the tank 14 at the time T39 as a threshold value, which causes the level sensor to output an ON signal at the time T39.

[0245] Then, until time T43 when the liquid delivery process starts, the control unit 3 appropriately replenishes DIW from the DIW supply unit to the mixed liquid M based on the signal from the level sensor, thereby maintaining the phosphoric acid concentration of the mixed liquid M at the third concentration.

[0246] Next, the control unit 3 starts the liquid transfer process from time T43. Specifically, the control unit 3 opens the first flow regulator 23a (turns it to the ON state) from time T43, and stops the first heater 19 (turns it to the OFF state). The subsequent processes are the same as those in the embodiment shown in FIG. 3 and the like, and therefore will not be described in detail.

[0247] As described above, in Modification 3, after the concentration adjustment process for adjusting the concentration of the phosphoric acid aqueous solution, a mixing process for mixing the phosphoric acid aqueous solution with a precipitation inhibitor is performed. This also makes it possible to further stabilize the phosphoric acid concentration in the etching solution E, so that the etching process of the wafer W using the etching solution E can be appropriately performed.

[0248] In the third modification, the phosphoric acid concentration of the mixed solution M is adjusted based on a level sensor that measures the liquid volume of the tank 14 based on the head pressure at the bottom of the tank 14. This makes it possible to stably maintain the phosphoric acid concentration of the mixed solution M even if the liquid level is disturbed during the mixing process.

[0249] Fig. 13 is a timing chart showing a specific example of a behavior pattern of each part of the substrate processing system 1 in a process for maintaining the temperature and concentration of the mixed liquid M in the processing tank 31 according to the third modified example of the embodiment. Fig. 13 is a diagram for explaining a temperature and concentration maintaining process that is performed after the mixing process shown in Fig. 12 is completed and before the liquid sending process is started.

[0250] In this temperature and concentration maintaining process, the control unit 3 operates the DIW supply unit (turns it ON) at time T51 to supply DIW to the tank 14.

[0251] The time T51 is a predetermined time (for example, 180 seconds) that has elapsed since the time T42 shown in Fig. 12 (i.e., the time when the level sensor was previously switched to the OFF state). At the time T51, the first pump 16 and the first heater 19 are operating (ON state), whereas the phosphoric acid aqueous solution supply unit 11 and the precipitation inhibitor supply unit 12 are not operating (OFF state).

[0252] At time T51, the on-off valve 21a is in a closed state, and therefore the filter 18 is not bypassed by the bypass passage 21 (filter bypass is in an OFF state).

[0253] Then, at time T52 when the head pressure at the bottom of the tank 14 exceeds the predetermined threshold value set at the above-mentioned time T39 and an ON signal is output from the level sensor, the control unit 3 stops the DIW supply unit (switches it to the OFF state).

[0254] On the other hand, since the first heater 19 continues to operate after time T52, the mixed liquid M in the mixing device 10 continues to evaporate, so that the head pressure at the bottom of the tank 14 becomes lower than the predetermined threshold value at time T53, and an OFF signal is output from the level sensor at time T53.

[0255] Then, at time T54, which is a predetermined time (for example, 180 (seconds)) after time T53, the control unit 3 operates (turns on) the DIW supply unit to supply DIW to the tank 14.

[0256] Then, at time T55 when the head pressure at the bottom of the tank 14 exceeds a predetermined threshold and an ON signal is output from the level sensor, the control unit 3 stops the DIW supply unit (sets it to the OFF state). The subsequent processing is a repetition of the processing described up to this point, as shown in FIG. 13, and therefore detailed description thereof will be omitted.

[0257] As described above, in the temperature concentration maintenance process in variant example 3, DIW is appropriately replenished from the DIW supply unit to the mixed liquid M based on a signal from the level sensor until the liquid delivery process is started, and the phosphoric acid concentration of the mixed liquid M is maintained at the third concentration.

[0258] In addition, in the third variant, rather than operating the DIW supply unit immediately at the timing when the OFF signal is output from the level sensor (for example, at time T53), it is preferable to operate the DIW supply unit after a predetermined time (for example, 180 seconds) has elapsed.

[0259] This allows the mixed solution M to be replenished with DIW while taking into consideration the time required from when DIW is supplied to the tank 14 until the DIW is reflected in the concentration of the mixed solution M. Therefore, according to the third modification, the variation in the phosphoric acid concentration in the mixed solution M can be reduced.

[0260] In the above-described modified example 3, when the mixed liquid M is initially delivered to the processing tank 31, the mixing process is performed after the concentration adjustment process, but the present disclosure is not limited to such an example. For example, as shown in Fig. 4, in the preparation and delivery process of the mixed liquid M that is delivered when the etching process for the wafer W is started in the processing tank 31 and silicon is eluted from the wafer W into the etching liquid E, the mixing process may be performed after the concentration adjustment process.

[0261] That is, in this variant example 3, when preparing the mixed solution M having a phosphoric acid concentration of the second concentration in the mixing device 10, the concentration of the phosphoric acid aqueous solution may be adjusted to the second concentration, and then a mixing process may be performed in which the phosphoric acid aqueous solution is mixed with a precipitation inhibitor.

[0262] The substrate processing apparatus (substrate processing system 1) according to the embodiment includes a processing tank 31, a mixer 10, a liquid delivery path 22, and a control unit 3. The processing tank 31 processes a substrate (wafer W) by immersing it in a processing liquid (etching liquid E). The mixer 10 mixes an aqueous phosphoric acid solution with an additive to generate a mixed liquid M that is a raw material for the processing liquid (etching liquid E). The liquid delivery path 22 delivers the mixed liquid M from the mixer 10 to the processing tank 31. The control unit 3 controls each unit. In addition, the control unit 3 delivers the mixed liquid M, in which the phosphoric acid concentration in the mixer 10 has become a second concentration higher than the first concentration when the phosphoric acid concentration is supplied to the mixer 10, from the mixer 10 to the processing tank 31 in which the substrate (wafer W) is immersed. This allows the etching process to be appropriately performed using the etching liquid E containing the aqueous phosphoric acid solution and the additive.

[0263] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the control unit 3 supplies an additive to the aqueous phosphoric acid solution supplied to the mixer 10 to generate a mixed liquid M, and then changes the phosphoric acid concentration of the mixed liquid M from a first concentration to a second concentration higher than the first concentration. This allows the etching process to be appropriately performed using the aqueous phosphoric acid solution and the etching liquid E containing the additive.

[0264] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, the control unit 3 adjusts the concentration of the aqueous phosphoric acid solution supplied to the mixing device 10 from a first concentration to a second concentration higher than the first concentration, and then mixes the additive into the aqueous phosphoric acid solution having the second concentration. This allows the etching process to be appropriately performed using the aqueous phosphoric acid solution and the etching solution E containing the additive.

[0265] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, the control unit 3 controls the phosphoric acid concentration of the mixed solution M, which is sent to the processing tank 31 and has a second phosphoric acid concentration, to a third concentration higher than the second concentration. This makes it possible to selectively etch the silicon nitride film formed on the wafer W efficiently.

[0266] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the control unit 3 sends the mixed liquid M having a second phosphoric acid concentration from the mixer 10 to the processing tank 31 before starting the immersion processing of the substrate (wafer W). The control unit 3 also sets the phosphoric acid concentration of the processing liquid (etching liquid E) made from the mixed liquid M to a third concentration higher than the second concentration. This allows the silicon nitride film formed on the wafer W to be selectively etched efficiently.

[0267] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the mixing device 10 has a heating mechanism (first heater 19). Moreover, the control unit 3 heats the mixed liquid M with the heating mechanism (first heater 19) to adjust the phosphoric acid concentration of the mixed liquid M to the second concentration. This makes it possible to efficiently generate the mixed liquid M having the second concentration, which has a high phosphoric acid concentration.

[0268] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, the liquid sending path 22 has branching portions 22b1 and 22b2. The substrate processing apparatus (substrate processing system 1) according to the embodiment further includes a return path 24 that returns the mixed liquid M from the branching portions 22b1 and 22b2 to the mixer 10. This makes it possible to more accurately perform a process that keeps the silicon concentration in the processing tank 31 constant or below a constant level, and to stably heat the mixed liquid M.

[0269] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, a plurality of mixers 10A, 10B are connected to one processing tank 31 via liquid transfer paths 22A, 22B. This makes it possible to more appropriately perform the etching process of the wafer W with the etching liquid E in one processing tank 31.

[0270] Furthermore, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the control unit 3 sequentially sends the mixed liquid M from one of the multiple mixers 10 to one processing tank 31 in which the substrate (wafer W) is being immersed. The control unit 3 also changes the phosphoric acid concentration of the mixed liquid M in the remaining mixing device 10 from the first concentration to the second concentration. This makes it possible to more appropriately perform the etching process of the wafer W with the etching liquid E in one processing tank 31.

[0271] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, a plurality of mixers 10A-10C are connected to a plurality of processing tanks 31A-31C via liquid transport paths 22A-22C. The liquid transport paths 22A-22C transport the mixed liquid from each mixer 10A-10C to each of the processing tanks 31A-31C individually. This allows the etching process of the wafer W with the etching liquid E to be more appropriately performed in the processing tanks 31A-31C.

[0272] Furthermore, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the control unit 3 sequentially sends the mixed liquid M from one of the multiple mixers 10 to the multiple processing tanks 31A-31C in which the substrates (wafers W) are immersed. The control unit 3 also changes the phosphoric acid concentration of the mixed liquid M from the first concentration to the second concentration in the remaining mixers 10. This makes it possible to more appropriately perform the etching process of the wafers W with the etching liquid E in the multiple processing tanks 31A-31C.

[0273] <Substrate processing details> Next, the substrate processing performed by the substrate processing system 1 according to the embodiment and the third modification will be described in detail with reference to Fig. 14 and Fig. 15. Fig. 14 is a flowchart showing the procedure of the substrate processing according to the embodiment.

[0274] First, the control unit 3 determines whether or not the wafer W is immersed in the processing tank 31 (step S101). If the wafer W is not immersed in the processing tank 31 (step S101, No), for example, when a liquid exchange process is performed in the processing tank 31, the control unit 3 performs a mixing process of mixing the phosphoric acid aqueous solution and the additive in the mixing device 10 (step S102).

[0275] Next, the control unit 3 controls the first heater 19 to carry out a concentration adjustment process for adjusting the phosphoric acid concentration of the produced mixed liquid M from the first concentration to a third concentration (step S103).

[0276] Next, the control unit 3 controls the mixing device 10 and the first liquid transfer path 22a to perform a liquid transfer process of transferring the mixed liquid M to the processing tank 31 (step S104). Then, the control unit 3 controls the substrate processing unit 30 to perform a heating process of heating the mixed liquid M (step S105).

[0277] In parallel with the process of step S105, the control unit 3 controls the silicon solution supply unit 25 to perform an addition process of adding the silicon solution to the mixed liquid M in the processing tank 31 (step S106).

[0278] Finally, the control unit 3 controls the substrate processing unit 30 to perform an immersion process in which the wafer W is immersed in the etching liquid E prepared in the processing tank 31 (step S107), and the process is completed.

[0279] In the above embodiment, an example has been described in which the phosphoric acid concentration of the mixed solution M is adjusted from the first concentration to the third concentration in the concentration adjustment process (step S103), but the present disclosure is not limited to this example.

[0280] For example, in the concentration adjustment process (step S103), the control unit 3 adjusts the phosphoric acid concentration of the mixed liquid M from a first concentration to a second concentration, and delivers the phosphoric acid of the second concentration into the treatment tank 31.

[0281] Then, in the heating process (step S105) of heating the mixed liquid M in the treatment tank 31, the control unit 3 may adjust the phosphoric acid concentration from the second concentration to the third concentration by controlling the second heater 41.

[0282] This also allows the wafer W to be immersed in the etching solution E in which the phosphoric acid concentration is adjusted to the third concentration, so that the silicon nitride film formed on the wafer W can be selectively etched efficiently.

[0283] On the other hand, when the wafer W is immersed in the processing tank 31 (step S101, Yes), for example, when the wafer W is being etched in the processing tank 31, the control unit 3 performs a mixing process in which the phosphoric acid aqueous solution and the additive are mixed in the mixing device 10 (step S108).

[0284] Next, the control unit 3 controls the first heater 19 to carry out a concentration adjustment process for adjusting the phosphoric acid concentration of the produced mixed liquid M from the first concentration to the second concentration (step S109).

[0285] Next, the control unit 3 controls the mixing device 10, the second liquid transfer path 22b, and the return path 24 to perform a liquid transfer process for transferring the mixed liquid M to the processing tank 31 (step S110). In parallel with the liquid transfer process, the control unit 3 also performs a discharge process for discharging the mixed liquid M containing the silicon solution from the processing tank 31 (step S111).

[0286] This makes it possible to always keep the silicon concentration of the etching solution E in the processing tank 31 constant or below a constant level. Then, when the processing of steps S110 and S111 ends, the processing is completed.

[0287] 15 is a flowchart showing a processing procedure for substrate processing according to Modification 3 of the embodiment. First, the control unit 3 determines whether or not the wafer W is immersed in the processing bath 31 (step S201).

[0288] Then, when the wafer W is not immersed in the processing tank 31 (step S201, No), for example when a liquid exchange process is performed in the processing tank 31, the control unit 3 performs a phosphoric acid supply process to supply an aqueous phosphoric acid solution to the mixing device 10 (step S202).

[0289] Next, the control unit 3 controls the first heater 19 to perform a concentration adjustment process to adjust the phosphoric acid concentration of the produced mixed solution M from the first concentration to a third concentration (step S203). Then, the control unit 3 performs a mixing process to mix the phosphoric acid aqueous solution that has been subjected to the concentration adjustment process with an additive in the mixer 10 (step S204).

[0290] Next, the control unit 3 controls the mixing device 10 and the first liquid transfer path 22a to perform a liquid transfer process of transferring the mixed liquid M to the processing tank 31 (step S205). Then, the control unit 3 controls the substrate processing unit 30 to perform a heating process of heating the mixed liquid M (step S206).

[0291] In parallel with the process of step S206, the control unit 3 controls the silicon solution supply unit 25 to perform an addition process of adding the silicon solution to the mixed liquid M in the processing tank 31 (step S207).

[0292] Finally, the control unit 3 controls the substrate processing unit 30 to perform an immersion process in which the wafer W is immersed in the etching liquid E prepared in the processing tank 31 (step S208), and the process is completed.

[0293] In the above-described third modification, an example has been shown in which the phosphoric acid concentration of the mixed solution M is adjusted from the first concentration to the third concentration in the concentration adjustment process (step S203), but the present disclosure is not limited to this example.

[0294] For example, in the concentration adjustment process (step S203), the control unit 3 adjusts the phosphoric acid concentration of the mixed liquid M from a first concentration to a second concentration, and delivers the phosphoric acid of the second concentration into the treatment tank 31.

[0295] Then, in the heating process (step S206) of heating the mixed liquid M in the treatment tank 31, the control unit 3 may control the second heater 41 to adjust the phosphoric acid concentration from the second concentration to the third concentration.

[0296] This also allows the wafer W to be immersed in the etching solution E in which the phosphoric acid concentration is adjusted to the third concentration, so that the silicon nitride film formed on the wafer W can be selectively etched efficiently.

[0297] On the other hand, when the wafer W is immersed in the processing tank 31 (step S201, Yes), for example, when the wafer W is being etched in the processing tank 31, the control unit 3 performs a phosphoric acid supply process to supply an aqueous phosphoric acid solution to the mixing device 10 (step S209).

[0298] Next, the control unit 3 controls the first heater 19 to perform a concentration adjustment process to adjust the phosphoric acid concentration of the produced mixed solution M from a first concentration to a second concentration (step S210). Then, the control unit 3 performs a mixing process to mix the phosphoric acid aqueous solution that has been subjected to the concentration adjustment process with an additive in the mixer 10 (step S211).

[0299] Next, the control unit 3 controls the mixing device 10, the second liquid transfer path 22b, and the return path 24 to perform a liquid transfer process of transferring the mixed liquid M to the processing tank 31 (step S212). In parallel with the liquid transfer process, the control unit 3 also performs a discharge process of discharging the mixed liquid M containing the silicon solution from the processing tank 31 (step S213).

[0300] This makes it possible to always keep the silicon concentration of the etching solution E in the processing tank 31 constant or below a constant level. Then, when the processing in steps S212 and S213 ends, the processing is completed.

[0301] The substrate processing method according to the embodiment includes a concentration adjusting step (step S109) and a liquid sending step (step S110). In the concentration adjusting step, a phosphoric acid concentration in the mixed liquid M is changed from a first concentration to a second concentration higher than the first concentration in a mixer 10 that mixes an aqueous phosphoric acid solution with an additive to generate a mixed liquid M that is a raw material for a processing liquid (etching liquid E). In the liquid sending step (step S110), the mixed liquid M with the phosphoric acid concentration at the second concentration is sent from the mixer 10 to a processing tank 31 in which a substrate (wafer W) is immersed. This allows an etching process to be appropriately performed using the etching liquid E containing an aqueous phosphoric acid solution and an additive.

[0302] The substrate processing method according to the embodiment includes a phosphoric acid aqueous solution supplying step (step S209), a concentration adjusting step (step S210), a mixing step (step S211), and a liquid sending step (step S212). The phosphoric acid aqueous solution supplying step (step S209) supplies the phosphoric acid aqueous solution to a mixing device 10 that generates a mixed solution M that is a raw material of a processing liquid. The concentration adjusting step (step S210) adjusts the phosphoric acid aqueous solution from a first concentration to a second concentration higher than the first concentration. The mixing step (step S211) supplies an additive to the phosphoric acid aqueous solution to generate the mixed solution M. The liquid sending step (step S212) sends the mixed solution M from the mixing device 10 to a processing tank 31 in which a substrate (wafer W) is immersed. This allows the etching process to be appropriately performed using the phosphoric acid aqueous solution and the etching solution E containing the additive.

[0303] In the substrate processing method according to the embodiment, the phosphoric acid concentration of the mixed solution M, which has a second phosphoric acid concentration and is sent to the processing tank 31 in the sending step (step S110), is controlled to a third concentration higher than the second concentration. This makes it possible to selectively etch the silicon nitride film formed on the wafer W efficiently.

[0304] Moreover, in the substrate processing method according to the embodiment, before starting the immersion processing of the substrate, the mixed liquid M having a second phosphoric acid concentration is sent from the mixing device 10 to the processing tank 31, and the phosphoric acid concentration of the processing liquid (etching liquid E) made from the mixed liquid M as a raw material is set to a third concentration higher than the second concentration. This makes it possible to selectively etch the silicon nitride film formed on the wafer W efficiently.

[0305] Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present disclosure. For example, in the above embodiment, an example in which the concentration adjustment process is performed by heating the mixed liquid M is shown, but the concentration adjustment process of the mixed liquid M is not limited to the case in which the mixed liquid M is heated.

[0306] For example, the mixed liquid M can be evaporated by reducing the pressure of the atmosphere in the tank 14, and therefore the concentration of the mixed liquid M can be adjusted. In addition, in the above embodiment, a precipitation inhibitor that inhibits precipitation of silicon oxide is given as an example of an additive, but the additive may be, for example, a silicon compound additive, and does not necessarily have to be a precipitation inhibitor.

[0307] The disclosed embodiments should be considered to be illustrative and not restrictive in all respects. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0308] 1. Substrate processing system (an example of a substrate processing apparatus) 3. Control Unit 10, 10A~10C mixing device 11 Phosphoric acid aqueous solution supply section 12 Deposition inhibitor supply section 19 First heater (an example of a heating mechanism) 22, 22A to 22C Liquid delivery path 22b1, 22b2 branch 24, 24A~24C Return path 25 Silicone Solution Supply Section 30 Substrate processing section 31, 31A~31C Treatment tank W wafer (example of substrate) M mixture E Etching solution (an example of a processing solution)

Claims

1. a processing tank in which the substrate is immersed in a processing solution; a mixer for mixing an aqueous phosphoric acid solution with an additive to generate a mixed solution that is a raw material for the treatment solution; a liquid transfer path for transferring the mixed liquid from the mixing device to the treatment tank; a silicon solution supply unit for supplying a silicon solution to the treatment tank; A control unit for controlling each unit; Equipped with The control unit is The concentration of the phosphoric acid aqueous solution supplied to the mixing device is adjusted from a first concentration when the phosphoric acid concentration is supplied to the mixing device to a third concentration higher than the first concentration, and then the additive is mixed into the phosphoric acid aqueous solution having the third concentration; In the mixing device, the first mixed solution having the phosphoric acid concentration set to the third concentration is sent from the mixing device to the empty treatment tank; supplying the silicon solution to the first mixture in the treatment tank to generate the treatment solution; The substrate is carried into the treatment tank to start an immersion treatment of the substrate; The concentration of the aqueous phosphoric acid solution supplied to the mixing device is adjusted from the first concentration to a second concentration higher than the first concentration and lower than the third concentration, and then the additive is mixed into the aqueous phosphoric acid solution having the second concentration; A second mixed solution having a phosphoric acid concentration of the second concentration is sent from the mixing device to the treatment tank in which the substrate is immersed; Adjusting the silicon concentration of the processing solution in the processing tank Substrate processing equipment.

2. The liquid transfer path has a branching portion, a return path for returning the mixed liquid from the branching portion to the mixing device; The substrate processing apparatus according to claim 1 .

3. A plurality of the mixing devices are connected to one of the treatment tanks via the liquid transfer paths. The substrate processing apparatus according to claim 1 .

4. The control unit is The mixed liquid is sequentially delivered from one of the plurality of mixing devices to one of the processing tanks in which the substrate is immersed; The phosphoric acid concentration of the mixture is changed from the first concentration to the second concentration in the remaining mixing device. The substrate processing apparatus according to claim 3 .

5. A plurality of the mixing devices are connected to a plurality of the treatment tanks via the liquid transfer paths, The liquid transfer path transfers the mixed liquid from one of the mixing devices to the plurality of processing tanks individually. The substrate processing apparatus according to any one of claims 1 to 4.

6. The control unit is The mixed liquid is sequentially delivered from one of the plurality of mixing devices to the plurality of processing tanks in which the substrates are immersed; The phosphoric acid concentration of the mixture is changed from the first concentration to the second concentration in the remaining mixing device. The substrate processing apparatus according to claim 5 .

7. a first phosphoric acid aqueous solution supplying step of supplying a phosphoric acid aqueous solution to a mixer for producing a mixed liquid that is a raw material for the treatment liquid; a first concentration adjusting step of adjusting the phosphoric acid aqueous solution from a first concentration to a third concentration higher than the first concentration in the mixing device; a first mixing step of supplying an additive to the aqueous phosphoric acid solution having a phosphoric acid concentration of the third concentration in the mixing device to produce a first mixed solution; a first liquid delivery step of delivering the first mixed liquid from the mixing device to an empty treatment tank; a generating step of supplying a silicon solution to the first mixed liquid in the processing tank to generate the processing liquid; a starting step of carrying a substrate into the treatment tank and starting an immersion treatment of the substrate; A second phosphoric acid aqueous solution supplying step of supplying an aqueous phosphoric acid solution to the mixing device; a second concentration adjusting step of adjusting the phosphoric acid aqueous solution from a first concentration to a second concentration higher than the first concentration and lower than the third concentration in the mixing device; a second mixing step of supplying the additive to the aqueous phosphoric acid solution having a phosphoric acid concentration of the second concentration in the mixing device to produce a second mixed solution; a second liquid delivery step of delivering the second mixed liquid from the mixing device to the treatment tank in which the substrate is immersed; a third concentration adjusting step of adjusting a silicon concentration of the processing solution in the processing tank; A substrate processing method comprising:

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