Substrate processing apparatus and substrate processing method

Abstract

To provide a substrate processing apparatus and a substrate processing method that are capable of excellently reducing a silicon concentration in an etching solution.SOLUTION: A substrate processing apparatus 1 includes an etching processing section 2 that etches a substrate W with an etching solution, a discharge pipe 10 that discharges the etching solution from the etching processing section 2, and a solid silica unit 40 provided in the discharge pipe 10. The solid silica unit 40 includes a plurality of solid silicas 41, and a silica storage section 42 that stores the plurality of solid silicas 41 and allows the etching solution to pass through the inside of the silica storage section 42. The silica storage section 42 has a cylindrical space filled with the plurality of solid silicas 41. The discharge pipe 10 includes an upstream discharge pipe 11 and a downstream discharge pipe 12 that are connected to one end and the other end in an axial direction of the cylindrical space, respectively.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate processing apparatus and a substrate processing method for processing a substrate. Substrates to be processed include, for example, semiconductor wafers, substrates for FPDs (Flat Panel Displays) such as liquid crystal displays and organic EL (Electroluminescence) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells. [Background technology]

[0002] Silicon oxide is dissolved in the phosphoric acid aqueous solution used in the etching process of a substrate. Therefore, to prevent the concentration of silicon oxide in the phosphoric acid aqueous solution (hereinafter sometimes referred to as "silicon concentration") from exceeding the saturation concentration and resulting in deposition on the substrate, a method is used in which the silicon concentration is adjusted by replenishing the phosphoric acid aqueous solution during the etching process of the substrate. This requires a large amount of phosphoric acid aqueous solution to adjust the silicon concentration.

[0003] Therefore, Patent Documents 1 and 2 below propose a method for reusing the phosphoric acid aqueous solution used in etching a substrate. Specifically, Patent Document 1 discloses a method of removing silicon oxide from an aqueous phosphoric acid solution by cooling the aqueous phosphoric acid solution in a storage tank using a temperature control mechanism to precipitate silicon oxide in the aqueous phosphoric acid solution, and then filtering the aqueous phosphoric acid solution with a filter.

[0004] Patent Document 2 discloses a method in which pure water is supplied to an aqueous phosphoric acid solution used in an etching process to dilute the aqueous phosphoric acid solution, thereby precipitating silicon oxide, and then the aqueous phosphoric acid solution is filtered.Then, water is evaporated from the aqueous phosphoric acid solution to concentrate the aqueous phosphoric acid solution, which is then supplied to an etching tank. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5829444 [Patent Document 2] Patent No. 3788985 Summary of the Invention [Problem to be solved by the invention]

[0006] In the methods disclosed in Patent Documents 1 and 2, the filter becomes clogged by capturing the precipitated silicon oxide, which requires the time and effort of periodically replacing the filter. Furthermore, in the method of Patent Document 1, the entire storage tank needs to be cooled to precipitate silicon oxide, while in the method of Patent Document 2, the water in the phosphoric acid aqueous solution needs to be evaporated. Therefore, in both the methods of Patent Documents 1 and 2, it takes a relatively long time to precipitate silicon oxide.

[0007] An object of the present invention is to provide a substrate processing apparatus and a substrate processing method that can effectively reduce the silicon concentration in an etching solution. [Means for solving the problem]

[0008] One embodiment of the present invention provides a substrate processing apparatus including an etching processing section that etches a substrate with an etching solution, a discharge flow path that discharges the etching solution from the etching processing section, and a solid silica unit provided in the discharge flow path, wherein the solid silica unit includes a plurality of solid silica particles and a silica container that contains the plurality of solid silica particles and allows the etching solution to pass through the interior of the silica container.

[0009] According to this substrate processing apparatus, the etching solution used in etching the substrate is discharged from the etching processing section to the discharge flow path. The solid silica unit provided in the discharge flow path includes a silica container that contains multiple solid silica particles. As a result, the etching solution is efficiently cooled by contact with the multiple solid silica particles as it passes through the silica container. As a result, silicon oxide dissolved in the etching solution precipitates and adheres to the surfaces of the multiple solid silica particles. In this way, silicon oxide can be rapidly precipitated from the etching solution.

[0010] Furthermore, sufficiently large gaps are formed between adjacent solid silica particles, which can prevent the gaps between adjacent solid silica particles from being blocked when silicon oxide is deposited on the surface of the solid silica. As a result, the silicon concentration in the etching solution can be reduced effectively. In one embodiment of the present invention, the solid silica has a granular shape with corners. The present inventors have found that when solid silica with a granular shape with corners is used, liquid exchange of the etching solution is likely to occur around the corners, and therefore silicon oxide is likely to precipitate at the corners and their surroundings on the surface of the solid silica. Therefore, by using solid silica with a granular shape with corners, silicon oxide dissolved in the etching solution can be effectively precipitated. Examples of the shape of such solid silica include a polyhedral shape and a pellet shape.

[0011] In one embodiment of the present invention, the particle size of the solid silica is 1 mm or more and 10 mm or less. When the particle size of the solid silica is in this range, gaps of an appropriate size are formed between adjacent solid silica particles. When silicon oxide is deposited on the surface of the solid silica, the gaps between adjacent solid silica particles can be further prevented from being blocked. In one embodiment of the present invention, the silica storage section includes a cylindrical space filled with a plurality of the solid silica particles, and the discharge flow path includes an upstream discharge flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream discharge flow path connected to the other end of the cylindrical space in the axial direction.

[0012] In this substrate processing apparatus, the etching solution flows from one end to the other in the axial direction within the cylindrical space. This allows for increased uniformity of the linear velocity of the etching solution at each position in the axial direction of the cylindrical space. This facilitates the deposition of silicon oxide over the entirety of the multiple solid silica particles within the cylindrical space. As a result, the silicon concentration in the etching solution can be effectively reduced.

[0013] In one embodiment of the present invention, the silica storage section includes a liquid storage section that stores a plurality of solid silica particles therein and stores the etching liquid. According to this substrate processing apparatus, the etching liquid discharged from the etching processing unit to the discharge flow path is stored in the liquid storage unit, and silicon oxide is precipitated from the etching liquid by the plurality of solid silica particles. Therefore, even when a large amount of etching liquid is discharged from the etching processing unit, the silicon concentration in the etching liquid can be effectively reduced. As a result, the amount of etching liquid to be disposed of can be reduced.

[0014] In one embodiment of the present invention, the substrate processing apparatus further includes a cooling unit for cooling the plurality of solid silica particles. Therefore, if the plurality of solid silica particles are cooled in advance, the etching solution can be rapidly cooled as it passes through the solid silica unit. This allows silicon oxide to be rapidly deposited. In one embodiment of the present invention, the cooling unit includes a coolant supply passage that supplies a coolant to the silica accommodating section and a coolant discharge passage that discharges the coolant from the silica accommodating section. According to this substrate processing apparatus, the plurality of solid silica particles can be cooled by supplying the coolant to the silica accommodating section. Therefore, compared to a case where the plurality of solid silica particles are cooled from the outside of the silica accommodating section, the solid silica particles located relatively inside the silica accommodating section can be cooled more quickly. As a result, the silicon concentration in the etching solution can be effectively reduced.

[0015] In one embodiment of the present invention, the substrate processing apparatus further includes a concentration measurement unit that measures the silicon concentration in the etching solution at a predetermined measurement position downstream of the solid silica unit in the discharge flow path, an etching solution tank that stores the etching solution, and a discharge flow path opening / closing unit that is provided in the discharge flow path downstream of the measurement position and that opens and closes the discharge flow path.

[0016] The ability of the solid silica unit to remove silicon oxide from the etching solution (removal ability) decreases as the etching solution continues to pass through the solid silica unit. Specifically, the solid silica units cool the etching solution, causing the temperature of the solid silica units to rise, thereby decreasing the ability to cool the etching solution. When the removal capacity of the solid silica unit is sufficiently high, the silicon concentration of the etching solution passing through the solid silica unit is sufficiently reduced, and when the removal capacity of the solid silica unit is not sufficiently high, the silicon concentration of the etching solution passing through the solid silica unit is not sufficiently reduced.

[0017] According to this substrate processing apparatus, it is possible to cause the etching liquid to flow into the etching liquid tank or to stop the flow of the etching liquid into the etching liquid tank, so that, for example, if the silicon concentration measured by the concentration measuring unit is equal to or less than a predetermined threshold, the etching liquid flows into the etching liquid tank, and if the silicon concentration measured by the concentration measuring unit is above the threshold, the discharge flow path opening / closing unit can open or close the discharge flow path so that the flow of the etching liquid into the etching liquid tank is stopped.

[0018] By opening and closing the discharge flow path in this way, when the removal capacity of the solid silica unit is sufficiently high, the etching liquid is supplied to the etching liquid tank. On the other hand, when the removal capacity of the solid silica unit decreases and the silicon concentration of the etching liquid passing through the solid silica unit becomes higher than the threshold, the supply of the etching liquid to the etching liquid tank is stopped. Therefore, etching liquid with a sufficiently reduced silicon concentration can be selectively recovered in the etching liquid tank. As a result, etching liquid with a satisfactorily reduced silicon concentration can be recovered.

[0019] In one embodiment of the present invention, the substrate processing apparatus further includes a return flow path connected to the discharge flow path at the same position as the measurement position or at a position downstream of the measurement position, for returning the etching solution to the upstream side of the solid silica unit in the discharge flow path, and a return flow path opening / closing unit for opening and closing the return flow path. According to this substrate processing apparatus, it is possible to cause the etching liquid to flow into the return flow path or to stop the flow of the etching liquid into the return flow path. Therefore, for example, if the silicon concentration measured by the concentration measuring unit is equal to or less than a threshold value, the flow of the etching liquid into the return flow path is stopped, and if the silicon concentration measured by the concentration measuring unit is greater than the threshold value, the return flow path opening / closing unit can be made to open or close the return flow path so that the etching liquid flows into the return flow path.

[0020] By opening and closing the return flow path in this manner, the etching liquid that has returned to the discharge flow path via the return flow path can be passed again through the silica storage section of the solid silica unit. This allows silicon oxide to be further precipitated from the etching liquid, reducing the silicon concentration in the etching liquid. When the silicon concentration falls below a threshold value after passing through the solid silica unit multiple times, the flow of the etching liquid into the return flow path is stopped. Therefore, the etching liquid with a sufficiently reduced silicon concentration can be quickly flowed into the etching liquid tank. As a result, the etching liquid with a satisfactorily reduced silicon concentration can be recovered.

[0021] In one embodiment of the present invention, the substrate processing apparatus further includes a branch flow path that branches off from the discharge flow path downstream of a return position where the etching solution returns from the return flow path and upstream of the solid silica unit, and is connected downstream of the solid silica unit and upstream of the measurement position, and a branch flow path opening / closing unit that opens and closes the branch flow path.

[0022] According to this substrate processing apparatus, the etching liquid returned to the return position by the return flow path can be caused to flow into the branch flow path, or the etching liquid returned to the return position by the return flow path can be stopped from flowing into the branch flow path. Therefore, for example, when the silicon concentration measured by the concentration measurement unit exceeds a predetermined threshold, the branch flow path opening / closing unit can open or close the branch flow path so that the etching liquid returned to the return position by the return flow path flows into the branch flow path for a predetermined recovery time. By opening and closing the branch flow path in this manner, the etching liquid can be circulated in the branch flow path and the return flow path while the supply of the etching liquid to the solid silica unit is stopped.

[0023] Therefore, for example, while the etching solution is circulating in the branch flow path and the return flow path, the solid silica particles in the silica containing section can be cooled or replaced with sufficiently cooled solid silica particles. After a predetermined time has passed, the etching solution can be flowed into the solid silica unit whose removal capacity has been restored, rather than into the branch flow path.

[0024] In one embodiment of the present invention, the substrate processing apparatus further includes a circulation flow path that circulates the etching solution and is connected to the discharge flow path at the same position as the measurement position or downstream of the measurement position, and downstream of the solid silica unit and upstream of the measurement position, and a circulation flow path opening / closing unit that opens and closes the circulation flow path. According to this substrate processing apparatus, it is possible to cause the etching liquid to flow into the circulation flow path, or to stop the etching liquid from flowing into the circulation flow path and cause the etching liquid to flow into the return flow path.

[0025] Therefore, for example, if the silicon concentration measured by the concentration measuring unit is equal to or lower than a predetermined threshold, the inflow of the etching liquid into the return flow path and the circulation flow path is stopped, and if the silicon concentration measured by the concentration measuring unit exceeds the threshold, the circulation flow path can be opened or closed so that the etching liquid in the circulation flow path flows into the return flow path after flowing into the circulation flow path for a predetermined time. By opening and closing the circulation flow path in this manner, the etching liquid can be circulated in the circulation flow path while the supply of the etching liquid to the solid silica unit is stopped.

[0026] Therefore, for example, while the etching liquid is circulating in the circulation flow path, the plurality of solid silica particles in the silica accommodating unit can be cooled, or the plurality of solid silica particles in the silica accommodating unit can be replaced with sufficiently cooled solid silica particles. After a predetermined time has elapsed, the etching liquid in the circulation flow path is not allowed to flow into the circulation flow path, and the etching liquid in the circulation flow path is allowed to flow into the return flow path. Therefore, after the predetermined time has elapsed, the etching liquid can be allowed to flow into the solid silica unit whose removal ability has been restored.

[0027] In one embodiment of the present invention, the substrate processing apparatus further includes a supply passage that supplies the etching liquid in the etching liquid tank to the etching processing section. According to this substrate processing apparatus, the etching liquid stored in the etching liquid tank can be supplied to the etching processing unit through the supply flow path, and therefore the etching liquid with a sufficiently reduced silicon concentration can be reused for processing substrates in the etching processing unit.

[0028] In one embodiment of the present invention, a plurality of the solid silica units are provided and are arranged in series in the discharge flow path. This reduces the amount of silicon oxide removed per solid silica unit. Therefore, the recovery time of the removal ability of the solid silica unit can be delayed compared to a configuration in which a single solid silica unit is provided in the discharge flow path.

[0029] In another embodiment of the present invention, a plurality of the solid silica units are provided, and the plurality of solid silica units are arranged in parallel in the discharge flow path. Therefore, by keeping at least one of the plurality of solid silica units in a usable state, it is possible to continue removing silicon oxide from the etching solution. Therefore, while continuing to remove silicon oxide from the etching solution, it is possible to recover the removal capacity of the solid silica units that are not removing silicon oxide.

[0030] Another embodiment of the present invention provides a substrate processing method including an etching step of etching a substrate with an etching solution in an etching processing section, a discharge step of discharging the etching solution from the etching processing section, and a solid silica passing step of passing the etching solution discharged into the discharge flow path in the discharge step through a silica storage section that stores a plurality of solid silica particles. This substrate processing method provides the same effects as the above-mentioned substrate processing apparatus.

[0031] In another embodiment of the present invention, the substrate processing method further includes a concentration measuring step of measuring a silicon concentration in the etching solution that has passed through the solid silica unit, and a determination step of determining whether the silicon concentration measured in the concentration measuring step is equal to or less than a predetermined threshold value. The recovery process and the return process are selectively performed so that, if the silicon concentration measured by the concentration measurement process is determined to be equal to or less than the threshold value in the determination process, a recovery process is performed in which the etching liquid that has passed through the silica containing section is recovered into an etching liquid tank, and, if the silicon concentration measured by the concentration measurement process is determined to be not equal to or less than the threshold value in the determination process, a return process is performed in which the etching liquid is returned to the discharge flow path upstream of the silica containing section. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a substrate processing apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a solid silica unit provided in the substrate processing apparatus. [Figure 3A] FIG. 2 is a schematic diagram for explaining the shape of solid silica provided in the solid silica unit. [Figure 3B] FIG. 2 is a schematic diagram for explaining the shape of solid silica provided in the solid silica unit. [Figure 4] FIG. 4 is a block diagram showing an example of the electrical configuration of the main parts of the substrate processing apparatus. [Figure 5] FIG. 5 is a flowchart illustrating an example of the operation of the substrate processing apparatus. [Figure 6A] FIG. 6A is a schematic diagram for explaining an example of the operation of the substrate processing apparatus. [Figure 6B] FIG. 6B is a schematic diagram for explaining an example of the operation of the substrate processing apparatus. [Figure 6C] FIG. 6C is a schematic view for explaining an example of the operation of the substrate processing apparatus. [Figure 6D] FIG. 6D is a schematic diagram for explaining an example of the operation of the substrate processing apparatus. [Figure 7] FIG. 7 is a flowchart illustrating another example of the operation of the substrate processing apparatus. [Figure 8] FIG. 8 is a schematic view for explaining a first modified example of the substrate processing apparatus. [Figure 9] FIG. 9 is a schematic view for explaining a second modified example of the substrate processing apparatus. [Figure 10] FIG. 10 is a schematic view for explaining a substrate processing apparatus according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a schematic view for explaining a substrate processing apparatus according to a third embodiment of the present invention. [Figure 12] FIG. 12 is a schematic view for explaining a substrate processing apparatus according to a fourth embodiment of the present invention. [Figure 13] FIG. 13 is a schematic diagram for explaining a modified example of the solid silica unit. [Figure 14] FIG. 14 is a schematic view for explaining a modified example of the etching processing section provided in the substrate processing apparatus. [Figure 15] FIG. 15 is a schematic diagram for explaining the state near the surface of the substrate during etching processing. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First Embodiment FIG. 1 is a diagram showing the overall configuration of a substrate processing apparatus 1 according to a first embodiment of the present invention. The substrate processing apparatus 1 performs an etching process on the substrate W using an etching liquid such as an aqueous phosphoric acid solution, and also performs a regeneration process on the etching liquid used in the etching process. The etching liquid is not limited to an aqueous phosphoric acid solution, and may be, for example, a liquid in which an additive is added to an aqueous phosphoric acid solution. The temperature of the etching liquid used in the etching process is, for example, about 160°C.

[0034] The substrate W processed by the substrate processing apparatus 1 is, for example, a disk-shaped semiconductor wafer. Silicon oxide is formed on the surface of the substrate W by performing an etching process. The surface of the substrate W has, for example, a silicon oxide layer and a silicon nitride layer exposed. When such a substrate W is used, an etching solution selectively etches the silicon nitride layer. Silicon oxide formed by etching the silicon nitride layer dissolves slightly in the etching solution. The substrate W with the exposed silicon oxide layer and silicon nitride layer is used, for example, in the manufacturing process of a 3D NAND memory device.

[0035] The substrate processing apparatus 1 includes an etching processing section 2 that performs etching processing on substrates W, a discharge pipe 10 that discharges an etching liquid from the etching processing section 2, and an etching liquid tank 20 that receives the etching liquid from the discharge pipe 10 and stores the etching liquid. The discharge pipe 10 forms a discharge flow path. The substrate processing apparatus 1 further includes a supply pipe 30 that supplies an etching solution to the etching processing unit 2, a solid silica unit 40 provided in the discharge pipe 10, and a concentration measuring unit 50 that measures the concentration of silicon oxide (silicon concentration) in the etching solution in the discharge pipe 10 downstream of the solid silica unit 40 in the discharge pipe 10. The substrate processing apparatus 1 further includes a controller 3 (see FIG. 4) that controls the substrate processing apparatus 1.

[0036] In this embodiment, the etching processing unit 2 is an immersion processing unit that performs etching processing by immersing a plurality of substrates W (for example, 50 substrates) in an etching solution. The etching processing unit 2 includes an immersion processing tank 4 that stores the etching solution and allows the etching processing to proceed. The immersion treatment tank 4 has a double tank structure. More specifically, the immersion treatment tank 4 includes an inner tank 5 that stores an etching solution and immerses the substrate W in the etching solution, an outer tank 6 that surrounds at least the upper end of the inner tank 5 and allows the etching solution to be exchanged with that in the inner tank 5, and a lifter 7 that raises and lowers the substrate W relative to the inner tank 5.

[0037] The inner tank 5 is a container that is rectangular in plan view and made of quartz or a fluororesin material that has excellent corrosion resistance against the etching solution. The outer tank 6 is made of the same material as the inner tank 5. The lifter 7 holds multiple substrates W together using multiple holding rods (not shown). The multiple substrates W are held by the lifter 7 in an upright position (a position in which the normal to the main surfaces of the substrates is horizontal) and arranged parallel to one another. The lifter 7 can be raised and lowered vertically by a lifting mechanism (not shown) having an electric motor or an air cylinder. The lifter 7 raises and lowers between a processing position (position in FIG. 1) where the multiple substrates W (lot) it holds are immersed in the etching solution in the inner bath 5, and a delivery position above the surface of the etching solution.

[0038] The discharge pipe 10 includes an upstream discharge pipe 11 located upstream of the solid silica unit 40, and a downstream discharge pipe 12 located downstream of the solid silica unit 40. The upstream end of the discharge pipe 10 (the upstream end of the upstream discharge pipe 11) is connected to the outer tank 6 of the immersion treatment tank 4. The downstream end of the discharge pipe 10 (the downstream end of the downstream discharge pipe 12) is connected to the etching solution tank 20. The downstream end of the discharge pipe 10 is located above the liquid level of the etching solution. The upstream discharge pipe 11 constitutes an upstream discharge flow path, and the downstream discharge pipe 12 constitutes a downstream discharge flow path.

[0039] As will be described in detail later, the solid silica unit 40 includes a plurality of solid silica particles 41 and a silica storage section 42 that stores the plurality of solid silica particles 41. The solid silica unit 40 cools the etching solution, causing silicon oxide to precipitate from the etching solution, thereby reducing the silicon concentration in the etching solution. Therefore, the solid silica unit 40 discharges the etching solution with the reduced silicon concentration downstream.

[0040] The downstream end of the upstream discharge pipe 11 and the upstream end of the downstream discharge pipe 12 are connected to the silica accommodating section 42. The etching liquid flows from the upstream discharge pipe 11 into the silica accommodating section 42 and flows from the silica accommodating section 42 to the downstream discharge pipe 12. The etching liquid is cooled by the plurality of solid silica particles 41 as it passes through the internal space of the silica accommodating section 42. As a result, silicon oxide in the etching liquid precipitates and adheres to the surfaces of the plurality of solid silica particles 41.

[0041] The temperature of the plurality of solid silica particles 41 is preferably lower than the temperature of the etching liquid flowing into the silica storage portion 42, and is preferably, for example, room temperature (for example, 25° C.) or lower. The concentration measurement unit 50 is also called a concentration monitor. The concentration measurement unit 50 measures the silicon concentration in the etching solution by an electrochemical measurement method using, for example, an ion selective electrode (ISE). The concentration measurement unit 50 using the ion selective electrode method can accurately measure the silicon concentration in the etching solution, although it takes several minutes to complete the measurement.

[0042] An example of an electrochemical measurement method is a method using a fluoride ion selective electrode (FISE). Specifically, hydrofluoric acid (HF) is dropped into a phosphoric acid solution containing dissolved silicon oxide. This produces H2SiF6, and the concentration of silicon oxide in the phosphoric acid solution can be calculated based on the change in voltage due to the amount of fluoride ions consumed during the process.

[0043] The concentration measurement unit 50 includes a measurement pipe 51 connected to a measurement position 12a set in the downstream discharge pipe 12, and a measuring instrument 52 that acquires the etching solution through the measurement pipe 51 and measures the silicon concentration in the acquired etching solution. Unlike this embodiment, the concentration measurement unit 50 may not include the measurement pipe 51, and the measurement device 52 of the concentration measurement unit 50 may be interposed in the downstream discharge pipe 12. In this case, the interior of the measurement device 52 forms part of the discharge flow path, and the internal flow path of the measurement device 52 is the measurement position 12a. The pipe upstream of the concentration measurement unit 50, the pipe downstream of the concentration measurement unit 50, and the return pipe 60, which will be described later, are connected to the measurement device 52.

[0044] The substrate processing apparatus 1 further includes a return pipe 60 connected to a position (measurement position 12a) in the discharge pipe 10 where measurement is performed by the concentration measurement unit 50 and returning the etching solution to the upstream side of the solid silica unit 40 in the discharge pipe 10, and a return valve 61 installed in the return pipe 60. The return pipe 60 forms a return flow path, and the return valve 61 is an example of a return flow path opening / closing unit that opens and closes the return flow path.

[0045] The substrate processing apparatus 1 further includes a branch pipe 70 that branches off from the upstream discharge pipe 11 downstream of a return position 11a to which the downstream end of the return pipe 60 is connected and upstream of the solid silica unit 40, and is connected downstream of the solid silica unit 40 and upstream of the measurement position 12a, and a branch valve 71 that is installed in the branch pipe 70. The branch pipe 70 forms a branch flow path, and the branch valve 71 is an example of a branch flow path opening / closing unit that opens and closes the branch flow path.

[0046] By returning the etching liquid to a position upstream of the solid silica unit 40 in the upstream discharge pipe 11 using the return pipe 60, the etching liquid that has passed through the solid silica unit 40 once can be made to pass through the solid silica unit 40 again. By causing the etching liquid that has returned to the return position 11a to flow into the branch pipe 70, the etching liquid can be circulated in the return pipe 60, the upstream discharge pipe 11, and the branch pipe 70 while the supply of the etching liquid to the solid silica unit 40 is stopped.

[0047] The substrate processing apparatus 1 further includes an upstream discharge pump 13, a first upstream discharge valve 14, a second upstream discharge valve 15, a downstream discharge pump 16, and a downstream discharge valve 17. The upstream discharge pump 13, the first upstream discharge valve 14, the second upstream discharge valve 15, the downstream discharge pump 16, and the downstream discharge valve 17 are arranged in this order from the upstream side to the downstream side of the discharge pipe 10. More specifically, the upstream discharge pump 13, the first upstream discharge valve 14, and the second upstream discharge valve 15 are arranged in the upstream discharge pipe 11, and the downstream discharge pump 16 and the downstream discharge valve 17 are arranged in the downstream discharge pipe 12.

[0048] The upstream discharge pump 13 sends the etching solution in the outer tank 6 of the immersion treatment tank 4 to the upstream discharge pipe 11 of the discharge pipe 10. The first upstream discharge valve 14 is disposed in the upstream discharge pipe 11 upstream of the return position 11a. The second upstream discharge valve 15 is disposed in the upstream discharge pipe 11 downstream of the upstream branch position 11b to which the upstream end of the branch pipe 70 is connected.

[0049] The first upstream discharge valve 14 is an example of a first upstream discharge flow path opening and closing unit that opens and closes the upstream discharge flow path formed by the upstream discharge pipe 11. The second upstream discharge valve 15 is an example of a second upstream discharge flow path opening and closing unit that opens and closes the upstream discharge flow path formed by the upstream discharge pipe 11 on the downstream side of the first upstream discharge valve 14. The downstream discharge pump 16 is disposed in the downstream discharge pipe 12 downstream of a downstream branch position 12b to which the downstream end of the branch pipe 70 is connected and upstream of a measurement position 12a. The downstream discharge valve 17 is disposed in the downstream discharge pipe 12 downstream of the measurement position 12a. The downstream discharge valve 17 is an example of a downstream discharge flow path opening and closing unit that opens and closes the downstream discharge flow path formed by the downstream discharge pipe 12.

[0050] The upstream end of the supply pipe 30 is connected to the etching liquid tank 20. The supply pipe 30 extends into the etching liquid tank 20 so that the upstream end of the supply pipe 30 is located below the liquid level of the etching liquid. The downstream end of the supply pipe 30 faces the outer tank 6 from above so that the etching liquid can be supplied from the supply pipe 30 to the outer tank 6 of the immersion processing tank 4. The substrate processing apparatus 1 further includes a supply pump 31 installed in the supply pipe 30 and a supply valve 32 installed in the supply pipe 30 downstream of the supply pump 31. The supply pump 31 sends the etching liquid in the etching liquid tank 20 to the supply pipe 30. The supply pipe 30 forms a supply flow path, and the supply valve 32 is an example of a supply flow path opening and closing unit that opens and closes the supply flow path.

[0051] In this way, the etching liquid stored in the etching liquid tank 20 can be supplied to the etching processing unit 2 via the supply pipe 30. Therefore, the etching liquid whose silicon concentration has been reduced by the solid silica unit 40 can be reused for processing the substrate W in the etching processing unit 2. The substrate processing apparatus 1 further includes a temperature adjustment unit 21 that adjusts the temperature of the etching solution in the etching solution tank 20. The temperature adjustment unit 21 is, for example, a heater that heats the etching solution in the etching solution tank 20. The temperature adjustment unit 21 may be, for example, a heater that is attached to the side wall and bottom wall of the etching solution tank 20 from the outside, as shown in FIG. 1. Unlike in FIG. 1, the temperature adjustment unit 21 may be a heater immersed in the etching solution in the etching solution tank 20, or may be a heater that heats piping that circulates the liquid in the etching solution tank 20. The etching solution in the etching solution tank 20 is maintained at a high temperature of about 160°C by the temperature adjustment unit 21.

[0052] The substrate processing apparatus 1 further includes a waste liquid pipe 80 for disposing of the etching liquid in the discharge pipe 10, and a waste liquid valve 81 disposed in the waste liquid pipe 80. The waste liquid pipe 80 forms a waste liquid flow path. The waste liquid valve 81 is an example of a waste liquid flow path opening / closing unit that opens and closes the waste liquid flow path. The waste liquid pipe 80 is connected to the upstream discharge pipe 11 downstream of the upstream discharge pump 13 and upstream of the first upstream discharge valve 14. The waste liquid pipe 80 is a pipe for disposing of the etching liquid when the etching liquid flows from the etching processing unit 2 into the upstream discharge pipe 11 during a period when the inflow of the etching liquid into the solid silica unit 40 is stopped. The period during which the inflow of the etching liquid into the solid silica unit 40 is stopped is, for example, a period during which the concentration measuring unit 50 is measuring the silicon concentration in the etching liquid.

[0053] The substrate processing apparatus 1 further includes a new liquid pipe 90 that refills the etching liquid tank 20 with new etching liquid (new liquid), a new liquid pump 91 installed in the new liquid pipe 90, and a new liquid valve 92 installed in the new liquid pipe 90 downstream of the new liquid pump 91. The new liquid pipe 90 forms a new liquid flow path. The new liquid valve 92 is an example of a new liquid flow path opening / closing unit that opens and closes the new liquid flow path.

[0054] The substrate processing apparatus 1 further includes a cooling unit 100 that cools the plurality of solid silica particles 41. The cooling unit 100 includes a coolant supply pipe 101 that supplies a coolant to the internal space of the silica accommodation unit 42, a coolant pump 102 provided in the coolant supply pipe 101, a coolant supply valve 103 provided in the coolant supply pipe 101 downstream of the coolant pump 102, a coolant discharge pipe 104 that discharges the coolant from the internal space of the silica accommodation unit 42, and a coolant discharge valve 105 provided in the coolant discharge pipe 104. The coolant is, for example, deionized water (DIW) at a temperature below room temperature.

[0055] The coolant supply pipe 101 constitutes a coolant supply flow path, and the coolant supply valve 103 is an example of a coolant supply flow path opening / closing unit that opens and closes the coolant supply flow path. The coolant discharge pipe 104 constitutes a coolant discharge flow path, and the coolant discharge valve 105 is an example of a coolant discharge flow path opening / closing unit that opens and closes the coolant discharge flow path. The cooling unit 100 allows the cooling liquid to pass through the internal space of the silica storage portion 42, thereby cooling the plurality of solid silica particles 41. Therefore, the temperature of the plurality of solid silica particles 41, which has risen due to the passage of the etching liquid, can be lowered.

[0056] For example, if the plurality of solid silica particles 41 are cooled in advance, the etching solution can be rapidly cooled when passing through the solid silica unit 40. This allows silicon oxide to be rapidly deposited. The substrate processing apparatus 1 may include an inert gas supply unit 110 that supplies an inert gas such as nitrogen gas to the internal space of the silica accommodation unit 42. The inert gas supply unit 110 includes an inert gas pipe 111 connected to the silica accommodation unit 42 and an inert gas valve 112 that opens and closes the inert gas pipe 111.

[0057] The inert gas pipe 111 constitutes an inert gas supply flow path, and the inert gas valve 112 is an example of an inert gas supply flow path opening / closing unit that opens and closes the inert gas supply flow path. The inert gas supplied from the inert gas supply unit 110 can push out the coolant remaining in the silica accommodating section 42. This makes it possible to prevent the etching liquid and the coolant from mixing and reducing the concentration of the etching agent contained in the etching liquid when the etching liquid is passed through the internal space of the silica accommodating section 42 after the plurality of solid silica particles have been cooled with the coolant. The coolant discharge pipe 104 also functions as an inert gas discharge flow path, and the coolant discharge valve 105 also functions as an inert gas discharge flow path opening and closing unit that opens and closes the inert gas discharge flow path.

[0058] FIG. 2 is a schematic diagram of a solid silica unit 40. 2, the silica storage section 42 of the solid silica unit 40 is, for example, cylindrical. The silica storage section 42 has a cylindrical space 43 (internal space) filled with a plurality of solid silica particles 41. One end of the cylindrical space 43 in the axial direction X along the central axis A1 is connected to the downstream end of the upstream discharge pipe 11, and the other end of the cylindrical space 43 in the axial direction X is connected to the upstream end of the downstream discharge pipe 12.

[0059] The solid silica 41 has a granular shape, for example, a spherical shape as shown in FIG. 2 . The spherical shape is also called a bead shape. The etching solution EL flowing from the upstream discharge pipe 11 into the cylindrical space 43 passes through the gaps G between adjacent solid silica particles 41, as shown in the enlarged view of FIG. 2 , from one end of the cylindrical space 43 to the other. Therefore, the etching solution EL is efficiently cooled by contacting the multiple solid silica particles 41 as it passes through the silica storage section 42. As the etching solution EL is cooled, the saturated concentration of silicon oxide in the etching solution EL decreases. Therefore, silicon oxide dissolved in the etching solution EL precipitates and adheres to the surfaces of the multiple solid silica particles 41. In this way, silicon oxide is rapidly precipitated from the etching solution EL, effectively reducing the silicon concentration in the etching solution EL.

[0060] The etching solution EL is locally cooled by contacting the solid silica 41, causing silicon oxide to precipitate. Therefore, compared to a configuration in which the etching solution EL is stored in a bath and the bath is cooled to cool the entire etching solution EL, the amount of etching solution EL cooled at one time can be reduced, and silicon oxide can be precipitated quickly from the etching solution EL.

[0061] Furthermore, the contact area between the etching liquid EL and the plurality of solid silica particles 41 is larger than the contact area between the etching liquid EL and the bath in a configuration in which the bath is cooled to store the etching liquid EL. Specifically, since a plurality of solid silica particles 41 are provided, the total surface area of ​​the plurality of solid silica particles 41 can be made larger than the surface area of ​​the side and bottom walls of the bath. Therefore, by using a plurality of solid silica particles 41, the etching liquid EL can be cooled efficiently.

[0062] Furthermore, unlike this embodiment, in a configuration in which the etching solution EL is passed through a filter together with the precipitated silicon oxide to remove the silicon oxide from the etching solution EL, clogging of the filter is likely to occur. On the other hand, in the solid silica unit 40, a sufficiently large gap G is formed between adjacent solid silica particles 41, so that when silicon oxide is precipitated on the surface of the solid silica particle 41, the gap G between adjacent solid silica particles 41 can be prevented from being blocked.

[0063] The particle size R of the solid silica 41 is, for example, 1 mm or more and 10 mm or less. If the particle size R of the solid silica 41 is in this range, gaps G of an appropriate size are likely to be formed between adjacent solid silica particles 41. When silicon oxide is deposited on the surface of the solid silica 41, it is possible to further prevent the gaps G between adjacent solid silica particles 41 from being blocked. The particle size R of the solid silica 41 is a convenient value equivalent to the diameter of the solid silica 41 if it is assumed to be a perfect sphere. If the solid silica 41 has a spherical shape, the particle size R of the solid silica 41 is the diameter of the sphere.

[0064] As described above, by using the solid silica unit 40, the silicon concentration in the etching solution EL can be reduced effectively. Furthermore, the etching solution EL can be cooled simply by passing the etching solution EL through the silica containing section 42. That is, the etching solution EL can be cooled without providing a device for cooling the etching solution EL separately from the solid silica unit 40. Therefore, the solid silica unit 40 can be prevented from becoming large.

[0065] As described above, the etching liquid EL flows from one end to the other end in the axial direction X within the cylindrical space 43. This makes it possible to improve the uniformity of the linear velocity of the etching liquid EL at each position in the axial direction X of the cylindrical space 43. This makes it easier to deposit silicon oxide over the entirety of the plurality of solid silica particles 41 within the cylindrical space 43. The shape of the solid silica 41 is not limited to a sphere, but may be any particle shape of a certain size. The shape of the solid silica 41 may be, for example, an ellipsoid, a polyhedron (see FIG. 3A), or a pellet (see FIG. 3B).

[0066] If the solid silica 41 has a polyhedral or pellet shape, each solid silica 41 has corners 41a. In the case of a polyhedral shape, the corners 41a refer to vertices and edges. The pellet shape has a cylindrical surface 41b and a pair of spherical surfaces 41c provided at both ends of the cylindrical surface 41b in the axial direction. In the case of a pellet shape, the corners 41a are the intersections between the cylindrical surface 41b and the spherical surface 41c.

[0067] When the solid silica 41 has a pellet or polyhedron shape, the particle size R of the solid silica 41 is the average value of the straight line passing through the center of gravity of the solid silica 41 inside the solid silica 41 . The inventors of the present application have found that when granular solid silica 41 having corners 41a is used, liquid exchange of the etching solution EL is likely to occur around the corners 41a, and therefore silicon oxide is likely to precipitate at and around the corners 41a on the surface of the solid silica 41. Therefore, by using granular solid silica 41 having corners 41a, silicon oxide dissolved in the etching solution EL can be effectively precipitated.

[0068] The shape of the solid silica 41 having the corners 41a is not limited to a polyhedron or a pellet. The polyhedron shown in FIG. 3B is a regular hexahedron, but is not limited to a regular hexahedron and may be, for example, a regular octahedron or a regular dodecahedron. Furthermore, the polyhedron shape is not limited to a regular polyhedron, and may be any shape having corners 41a.

[0069] The controller 3 includes a microcomputer and controls, in accordance with a predetermined program, the control targets provided in the substrate processing apparatus 1. More specifically, the controller 3 includes a processor (CPU) 3a and a memory 3b storing a program, and is configured to perform various control processes for substrate processing by the processor 3a executing the program.

[0070] In particular, the controller 3 controls the operations of the etching processing unit 2, the temperature adjustment unit 21, the concentration measurement unit 50, the upstream discharge pump 13, the downstream discharge pump 16, the supply pump 31, the new liquid pump 91, the coolant pump 102, the first upstream discharge valve 14, the second upstream discharge valve 15, the downstream discharge valve 17, the supply valve 32, the return valve 61, the branch valve 71, the waste liquid valve 81, the new liquid valve 92, the coolant supply valve 103, the coolant discharge valve 105, the inert gas valve 112, etc. In addition, the controller 3 also controls the operations of the components provided in the substrate processing apparatus 1 according to each of the modifications described below and the substrate processing apparatuses 1P, 1Q, and 1R according to each of the embodiments.

[0071] Fig. 5 is a flowchart illustrating an example of the operation of the substrate processing apparatus 1. Figs. 6A to 6D are schematic views illustrating an example of the operation of the substrate processing apparatus 1. In Figs. 6A to 6D, open valves are shown in black, and closed valves are shown in white. A substrate W is immersed in the etching liquid contained in the immersion treatment tank 4 of the etching treatment unit 2. This allows the substrate W to be etched (etching process). As shown in FIG. 6A, for example, the etching liquid is supplied from the supply pipe 30 to the etching treatment unit 2 (supply process). While the supply process is being performed, the etching liquid is discharged from the etching treatment unit 2 to the upstream discharge pipe 11 to adjust the amount of liquid in the immersion treatment tank 4 (discharge process). The etching liquid discharged to the upstream discharge pipe 11 in the discharge process passes through the solid silica unit 40. More specifically, it passes through a silica storage section 42 that stores multiple solid silica particles (solid silica passing process). More specifically, the etching liquid flows into the internal space of the silica storage section 42 of the solid silica unit 40 and flows out of the internal space to the downstream discharge pipe 12. The etching liquid is cooled by the multiple solid silica particles 41 while passing through the solid silica unit 40 (etching liquid cooling process).

[0072] The etching liquid that has passed through the solid silica unit 40 reaches the measurement position 12a. Before the etching liquid reaches the measurement position 12a, the downstream discharge valve 17 is closed. Furthermore, the first upstream discharge valve 14 is closed, and the return valve 61 is opened (step S1 in FIG. 5). As a result, the etching liquid that has reached the measurement position 12a returns to the upstream discharge pipe 11 via the return pipe 60 (return process). The silicon concentration in the etching liquid that has reached the measurement position 12a is measured by the concentration measurement unit 50 (step S2 in FIG. 5: concentration measurement process). More specifically, a portion of the etching liquid that has reached the measurement position 12a is supplied to a measuring instrument 52 via a measurement pipe 51, and the measuring instrument 52 starts measuring the silicon concentration in the etching liquid.

[0073] Then, the controller 3 monitors whether or not the measurement of the silicon concentration in the etching liquid has been completed (step S3 in FIG. 5: measurement time monitoring step). Therefore, until a predetermined measurement time has elapsed (step S3 in FIG. 5: NO), the etching liquid that has returned to the upstream discharge pipe 11 via the return pipe 60 circulates through the upstream discharge pipe 11, the solid silica unit 40, the downstream discharge pipe 12, and the return pipe 60, as shown in FIG. 6B (first circulation step).

[0074] After a predetermined measurement time has elapsed (step S3 in FIG. 5: YES), the controller 3 determines whether the silicon concentration (measured concentration) measured by the concentration measuring unit 50 is equal to or lower than a predetermined threshold (step S4 in FIG. 5: determination step). If the controller 3 determines that the measured concentration is equal to or lower than the threshold value (step S4 in FIG. 5: YES), the return valve 61 is closed, and instead the downstream discharge valve 17 is opened (step S5 in FIG. 5). As a result, as shown in FIG. 6C, the circulation of the etching liquid is stopped, and the etching liquid is supplied to the etching liquid tank 20 via the downstream discharge piping 12. That is, the etching liquid in which the silicon concentration has been sufficiently reduced is recovered (recovery step).

[0075] If the controller 3 determines that the measured concentration exceeds the threshold value (step S4 in FIG. 5: NO), the second upstream discharge valve 15 is closed, and instead the branch valve 71 is opened (step S6 in FIG. 5). As a result, as shown in FIG. 6D, the supply of the etching liquid to the solid silica unit 40 is stopped, and the etching liquid circulates in the return pipe 60, the upstream discharge pipe 11, and the branch pipe 70 (second circulation step).

[0076] In this way, when the controller 3 determines that the measured concentration exceeds the threshold, the feedback process is also executed. Therefore, depending on the determination result of the determination process, the recovery process and the second circulation process (feedback process) are selectively executed. The controller 3 monitors whether a predetermined recovery time has elapsed since the branch valve 71 was opened and the second upstream discharge valve 15 was closed (step S7 in FIG. 5: recovery time monitoring step).

[0077] Until the recovery time has elapsed (step S7 in FIG. 5: NO), the cooling unit 100 cools the plurality of solid silica particles 41 in the solid silica unit 40 (solid silica cooling step). Specifically, the coolant supply valve 103 and the coolant discharge valve 105 are opened. This causes the coolant to be supplied to the internal space of the silica accommodating section 42 of the solid silica unit 40 (coolant supply step). The coolant supplied to the internal space of the silica accommodating section 42 passes through the silica accommodating section 42 and is discharged from the coolant discharge pipe 104 (coolant discharge step). The removal capacity of the solid silica unit 40 is restored by cooling the plurality of solid silica particles 41 with the coolant.

[0078] Unlike this embodiment, the plurality of solid silica particles 41 in the silica containing section 42 may be replaced with new solid silica particles 41, or the entire solid silica unit 40 may be replaced with a new solid silica unit 40, until the recovery time has elapsed. When the recovery time has elapsed (step S7 in FIG. 5: YES), the second upstream discharge valve 15 is opened, and instead the branch valve 71 is closed (step S8 in FIG. 5). As a result, as shown in FIG. 6B, the supply of the etching liquid to the solid silica unit 40 is resumed, and cooling of the etching liquid by the multiple solid silica particles 41 is resumed (etching liquid re-cooling step).

[0079] The etching liquid that has passed through the solid silica unit 40 again reaches the measurement position 12a. Thereafter, the process returns to step S2, and the concentration measurement unit 50 starts measuring the silicon concentration in the etching liquid again. If the measured concentration becomes equal to or lower than the predetermined threshold value due to the etching liquid being cooled again (step S4 in FIG. 5: YES), the return valve 61 is closed, and instead the downstream discharge valve 17 is opened (step S5 in FIG. 5). As a result, as shown in FIG. 6C, the circulation of the etching liquid is stopped, and the etching liquid is supplied to the etching liquid tank 20 via the downstream discharge piping 12. That is, the etching liquid whose silicon concentration has been sufficiently reduced is recovered (recovery process).

[0080] According to the first embodiment, the solid silica unit 40 can effectively reduce the silicon concentration in the etching solution. According to the first embodiment, the downstream discharge valve 17 allows the etching liquid to flow into the etching liquid tank 20 when the measured concentration is equal to or lower than a predetermined threshold, and stops the flow of the etching liquid into the etching liquid tank 20 when the measured concentration exceeds the threshold. Therefore, when the removal capacity of the plurality of solid silica particles 41 is sufficiently high, the etching liquid is supplied to the etching liquid tank 20. On the other hand, when the removal capacity of the plurality of solid silica particles 41 decreases and the silicon concentration of the etching liquid passing through the solid silica unit 40 becomes higher than the threshold, the supply of the etching liquid to the etching liquid tank 20 is stopped. Therefore, the etching liquid whose silicon concentration has been sufficiently reduced can be selectively recovered in the etching liquid tank 20.

[0081] According to the first embodiment, the return valve 61 stops the inflow of the etching liquid into the return pipe 60 if the measured concentration is equal to or less than the threshold, and allows the etching liquid to flow into the return pipe 60 if the measured concentration exceeds the threshold. Furthermore, if the measured concentration exceeds the threshold, the branch valve 71 allows the etching liquid returned to the return position 11a by the return pipe 60 to flow into the branch pipe 70 for a predetermined recovery time.

[0082] Therefore, if the measured concentration exceeds the threshold value, the etching liquid that has returned to the return position 11a via the return pipe 60 flows into the branch pipe 70 for a predetermined recovery time. As a result, the flow of the etching liquid into the solid silica unit 40 is stopped. Therefore, the etching liquid can be circulated in the branch pipe 70 and the return pipe 60 while the supply of the etching liquid to the solid silica unit 40 is stopped.

[0083] According to the first embodiment, the coolant supply valve 103 causes the coolant to flow into the coolant supply pipe 101 during the recovery time. Therefore, while the inflow of the etching liquid into the solid silica unit 40 is stopped, the coolant is supplied to the silica accommodating portion 42, thereby cooling the plurality of solid silica particles 41. Therefore, compared to the case where the plurality of solid silica particles 41 are cooled from the outside of the silica accommodating portion 42, the solid silica particles 41 located relatively inside can be cooled more quickly.

[0084] 7 is a flowchart illustrating another example of operation of the substrate processing apparatus 1. The example of operation shown in FIG. 7 differs from the example of operation shown in FIG. 5 in that when the controller 3 determines in step S4 that the measured concentration exceeds a predetermined threshold (step S4 in FIG. 7: YES), the branch valve 71 is not opened, but the second upstream discharge valve 15 remains open, and measurement of the silicon concentration in the etching solution is started again by the concentration measuring unit 50 (step S10 in FIG. 7). As a result, during the measurement time in step S3, as shown in FIG. 6B, the etching solution returned to the upstream discharge pipe 11 via the return pipe 60 passes through the silica accommodating portion 42 of the solid silica unit 40 again, which further precipitates silicon oxide from the etching solution and reduces the silicon concentration in the etching solution.

[0085] After step S10, the controller 3 monitors whether the measurement of the silicon concentration in the etching solution has been completed (step S11 in FIG. 7: measurement time monitoring step). Therefore, until a predetermined measurement time has elapsed (step S11 in FIG. 7: NO), the etching solution that has returned to the upstream discharge pipe 11 via the return pipe 60 continues to circulate through the upstream discharge pipe 11, the solid silica unit 40, the downstream discharge pipe 12, and the return pipe 60, as shown in FIG. 6B.

[0086] After a predetermined measurement time has elapsed (step S11 in FIG. 7: YES), the controller 3 determines whether the measured concentration is equal to or less than a predetermined threshold value (step S12 in FIG. 7: determination step). If the controller 3 determines that the measured concentration is equal to or lower than the threshold value (step S12 in FIG. 7: YES), the return valve 61 is closed, and instead the downstream discharge valve 17 is opened (step S5 in FIG. 7). If the controller 3 determines that the measured concentration exceeds the threshold value (step S12 in FIG. 7: NO), steps S6 to S8 are executed, and then the process returns to step S2, as in the example of operation shown in FIG.

[0087] In the following, modifications (first and second modifications) of the substrate processing apparatus 1 according to the first embodiment will be described. 8 is a schematic diagram for explaining a first modified example of the substrate processing apparatus 1. As shown in FIG. 8, the downstream end of the supply pipe 30 may be connected to the lower end of the inner bath 5 of the immersion processing bath 4.

[0088] 9 is a schematic diagram illustrating a second modified example of the substrate processing apparatus 1. As shown in FIG. 9, the substrate processing apparatus 1 may include a dissolving liquid supply unit 150 that supplies a dissolving liquid such as hydrofluoric acid (hydrofluoric acid) to the plurality of solid silica particles 41 to dissolve and remove silicon oxide deposited on the surfaces of the plurality of solid silica particles 41. The dissolving liquid supply unit 150 includes, for example, a dissolving liquid supply pipe 151 that supplies the dissolving liquid to the silica accommodation portion 42, and a dissolving liquid supply valve 152 that is disposed in the dissolving liquid supply pipe 151. The downstream end of the dissolving liquid supply pipe 151 may be branched and connected to the cooling liquid supply pipe 101. The dissolving liquid supply pipe 151 forms a dissolving liquid supply flow path, and the dissolving liquid supply valve 152 is an example of a dissolving liquid supply flow path opening and closing unit that opens and closes the dissolving liquid supply flow path.

[0089] The coolant discharge pipe 104 also functions as a dissolving liquid discharge pipe that discharges the dissolving liquid from the silica containing section 42. The dissolving liquid supply unit 150 may include a pump (not shown) that sends the dissolving liquid to the dissolving liquid supply pipe 151. For example, after removing silicon oxide from the surfaces of the plurality of solid silica particles 41 with a dissolving liquid, the plurality of solid silica particles 41 may be cooled with a cooling liquid while the dissolving liquid is replaced from the silica containing portion 42 with a cooling liquid.

[0090] Second Embodiment Next, the configuration and operation of a substrate processing apparatus 1P according to a second embodiment will be described. Fig. 10 is a schematic diagram for explaining the substrate processing apparatus 1P. In Fig. 10, the same reference numerals as in Fig. 1 etc. are used for components equivalent to those shown in Figs. 1 to 9, and descriptions thereof will be omitted.

[0091] The substrate processing apparatus 1P according to the second embodiment differs from the substrate processing apparatus 1 according to the first embodiment mainly in that a circulation pipe 120 for circulating the etching solution in the downstream discharge pipe 12 is provided instead of the branch pipe 70. The circulation pipe 120 is connected to a measurement position 12a on the downstream discharge pipe 12 and to an upstream position 12c on the downstream discharge pipe 12 downstream of the solid silica unit 40 and upstream of the measurement position 12a and the downstream discharge pump 16. A circulation valve 121 is installed in the circulation pipe 120. The circulation pipe 120 forms a circulation flow path, and the circulation valve 121 is an example of a circulation flow path opening and closing unit that opens and closes the circulation flow path.

[0092] The substrate processing apparatus 1P can be used to allow the etching liquid to flow into the circulation pipe 120, or to stop the flow of the etching liquid into the circulation pipe 120 and allow the etching liquid to flow into the return pipe 60. Therefore, for example, the following operations can be performed. If the measured concentration is equal to or less than a predetermined threshold, the circulation flow path is closed to stop the flow of the etching liquid into the return pipe 60 and the circulation pipe 120. Furthermore, if the measured concentration exceeds the threshold, the etching liquid flows into the circulation pipe 120 for a predetermined recovery time, and then the circulation flow path is opened to allow the etching liquid in the circulation pipe 120 to flow into the return pipe 60. By opening and closing the circulation flow path in this manner, the etching liquid can be circulated within the circulation pipe 120 while the supply of the etching liquid to the solid silica unit 40 is stopped.

[0093] Therefore, for example, the plurality of solid silica particles 41 in the silica containing section 42 can be cooled, or the plurality of solid silica particles 41 in the silica containing section 42 can be replaced with sufficiently cooled solid silica particles 41. After the recovery time has elapsed, the etching solution in the circulation pipe 120 flows into the return pipe 60. Therefore, after the recovery time has elapsed, the etching solution can be flowed into the solid silica unit 40 whose removal capacity has been restored. This allows silicon oxide to be removed from the etching solution.

[0094] Third Embodiment Next, the configuration and operation of a substrate processing apparatus 1Q according to a third embodiment will be described. Fig. 11 is a schematic diagram for explaining the substrate processing apparatus 1Q. Fig. 11 shows only the solid silica unit 40 and its surroundings in the substrate processing apparatus 1Q. In Fig. 11, components equivalent to those shown in Figs. 1 to 10 described above are assigned the same reference numerals as in Fig. 1, etc., and descriptions thereof will be omitted.

[0095] The substrate processing apparatus 1Q differs from the substrate processing apparatus 1 according to the first embodiment mainly in that two solid silica units 40 are arranged in series in the discharge pipe 10. The two solid silica units 40 have the same configuration. Each solid silica unit 40 is provided with a cooling unit 100. Although not shown, each solid silica unit 40 may be provided with an inert gas supply unit 110 (see FIG. 1).

[0096] The discharge pipe 10 includes an upstream discharge pipe 11 located upstream of the plurality of solid silica units 40, a downstream discharge pipe 12 located downstream of the plurality of solid silica units 40, and an intermediate discharge pipe 18 connecting the solid silica units 40 to each other. The solid silica unit 40 having a silica-accommodating section 42 connected to the downstream end of the upstream discharge pipe 11 is referred to as a first solid silica unit 40A, and the solid silica unit 40 having a silica-accommodating section 42 connected to the upstream end of the downstream discharge pipe 12 is referred to as a second solid silica unit 40B.

[0097] The upstream end of the intermediate discharge pipe 18 is connected to the silica accommodating section 42 of the first solid silica unit 40A, and the downstream end of the intermediate discharge pipe 18 is connected to the silica accommodating section 42 of the second solid silica unit 40B. If two solid silica units 40 are arranged in series, the amount of silicon oxide removed per solid silica unit 40 can be reduced. Therefore, compared to a configuration in which a single solid silica unit 40 is provided in the discharge pipe 10, the time required for the removal capacity of the solid silica unit 40 to be restored can be delayed.

[0098] Unlike the third embodiment, three or more solid silica units 40 may be arranged in series. <Fourth embodiment> Next, the configuration and operation of a substrate processing apparatus 1Q according to a fourth embodiment will be described. Fig. 12 is a schematic diagram for explaining a substrate processing apparatus 1R. Fig. 12 shows only the solid silica unit 40 and its surroundings in the substrate processing apparatus 1R. In Fig. 12, components equivalent to those shown in Figs. 1 to 11 are given the same reference numerals as in Fig. 1, etc., and descriptions thereof will be omitted.

[0099] The substrate processing apparatus 1R differs from the substrate processing apparatus 1 according to the first embodiment mainly in that two solid silica units 40 are arranged in parallel in the discharge pipe 10. The two solid silica units 40 have the same configuration. Each solid silica unit 40 is provided with a cooling unit 100. Although not shown, each solid silica unit 40 may be provided with an inert gas supply unit 110 (see FIG. 1).

[0100] The discharge pipe 10 includes an upstream discharge pipe 11 located upstream of one solid silica unit 40 (first solid silica unit 40A), a downstream discharge pipe 12 located downstream of the first solid silica unit 40A, and a branch discharge pipe 19 branched and connected to the upstream discharge pipe 11 and the downstream discharge pipe 12 and provided with the other solid silica unit 40 (second solid silica unit 40B). The substrate processing apparatus 1R further includes a branch discharge valve 19v interposed in the branch discharge pipe 19 upstream of the second solid silica unit 40B. The branch discharge pipe 19 forms a branch discharge flow path, and the branch discharge valve 19v is an example of a branch discharge flow path opening / closing unit that opens and closes the branch discharge flow path.

[0101] An upstream branch connection position 19a at which the branch discharge pipe 19 branches off and is connected to the upstream discharge pipe 11 is located downstream of an upstream branch connection position 11b of the branch pipe 70. A downstream branch connection position 19b at which the branch discharge pipe 19 branches off and is connected to the downstream discharge pipe 12 is located upstream of a downstream branch connection position 12b of the branch pipe 70. When two solid silica units 40 are arranged in parallel, the removal of silicon oxide from the etching solution can be continued as long as at least one of the two solid silica units 40 has sufficient removal capacity. In the example shown in FIG. 12, the first solid silica unit 40A is in a usable state. Therefore, while continuing to remove silicon oxide from the etching solution using the first solid silica unit 40A, the removal capacity of the second solid silica unit 40B can be restored. FIG. 12 shows a state in which the removal capacity of the second solid silica unit 40B is restored by cooling multiple solid silica 41 using the cooling unit 100.

[0102] Unlike the fourth embodiment, three or more solid silica units 40 may be arranged in parallel. Also, the third embodiment and the fourth embodiment may be combined. Specifically, a plurality of solid silica unit groups each configured by directly arranging a plurality of solid silica units 40 may be provided, and the plurality of solid silica unit groups may be arranged in parallel. <Other embodiments> The present invention is not limited to the above-described embodiment, and can be embodied in other forms.

[0103] 13, the silica storage section 42 of the solid silica unit 40 may be a liquid storage section 44 that stores a plurality of solid silica particles 41 therein and stores an etching liquid. The solid silica unit 40 may further include a storage filter 45 that stores a plurality of solid silica particles 41 and allows the etching liquid to pass through. The storage filter 45 preferably has a plurality of holes formed therein that are large enough to prevent the solid silica particles 41 from passing through (for example, a diameter of 1 mm or less).

[0104] As shown in FIG. 13, if the silica storage section 42 is a liquid storage section 44, the etching liquid discharged from the etching processing section 2 to the upstream discharge piping 11 can be stored in the liquid storage section 44, while silicon oxide can be precipitated from the etching liquid by a plurality of solid silica particles 41. 14, the etching processing unit 2 may be a single-wafer processing unit that ejects an etching liquid onto the substrates W to etch the substrates W one by one. In this case, the etching processing unit 2 includes a spin chuck 130 that rotates the substrate W about a vertical axis A2 passing through the center of the substrate W while holding the substrate W horizontally, an etching liquid nozzle 131 that ejects an etching liquid toward the upper surface of the substrate W held by the spin chuck 130, and a processing cup 132 that receives the etching liquid splashed from the substrate W. Although not shown, the etching processing unit 2 may be provided with a rinse liquid nozzle that ejects a rinse liquid toward the upper surface of the substrate W to wash the etching liquid off the upper surface of the substrate W.

[0105] The downstream end of supply pipe 30 is connected to etching liquid nozzle 131 , and the upstream end of upstream discharge pipe 11 of discharge pipe 10 is connected to the lower end of processing cup 132 . Except for the following points, even if the etching processing unit 2 is a single wafer processing unit, the same effects as when the etching processing unit 2 is an immersion processing unit can be achieved. The efficiency of replacing the etching liquid near the surface of the substrate W differs between when the etching processor 2 is a single-wafer processor and when the etching processor 2 is an immersion processor. Figure 15 is a schematic diagram for explaining the state near the surface of the substrate W during etching processing.

[0106] When the etching processing unit 2 is a single-wafer processing unit, the flow rate of the etching liquid supplied to the upper surface (upper main surface) of the substrate W is relatively high. Therefore, the etching liquid in the recesses 201 of the concave-convex pattern 200 formed on the upper surface of the substrate W is relatively easily replaced by new etching liquid newly supplied to the upper surface of the substrate W. The recesses 201 may be gaps between the structures 202 or holes formed in the structures 202.

[0107] The concave-convex pattern 200 is formed of, for example, a silicon oxide layer 203 and a silicon nitride layer 204. Specifically, the silicon nitride layer 204 is formed in a plurality of trenches 205 formed in the silicon oxide layer 203. An etching process may be performed to etch the silicon nitride layer 204 in the trenches 205. If the etching process is performed on the substrate W using a single-wafer processing system, the etching liquid in the trenches 205 can be quickly replaced with a new etching liquid, thereby quickly etching the silicon nitride layer 204.

[0108] On the other hand, when the etching processing unit 2 is an immersion processing unit, the flow rate of the etching liquid around the substrate W is relatively slow. Therefore, the etching liquid in the recesses 201 of the concave-convex pattern 200 formed on the upper surface of the substrate W is not easily replaced with the etching liquid outside the recesses 201. Therefore, compared to a single-wafer processing unit, it takes a longer time (e.g., 3 hours) to etch the silicon nitride layer 204. Therefore, the amount of etching liquid consumed is also larger than in a single-wafer processing unit.

[0109] Therefore, when the etching processing unit 2 is an immersion processing unit, as in the above-described embodiment, silicon oxide can be efficiently removed from the etching solution and the etching solution can be reused, thereby significantly reducing the consumption of the etching solution. Unlike the above-described embodiment, the concentration measuring unit 50 may not be provided. In this case, the degree of deterioration of the removal ability of the solid silica unit 40 may be determined based on the operating time of the solid silica unit 40. Specifically, the degree of deterioration of the removal ability of the solid silica unit 40 may be determined based on the time elapsed since the previous cooling by the cooling unit 100. If the multiple solid silica particles 41 have never been cooled by the cooling unit 100, the degree of deterioration of the removal ability of the solid silica unit 40 may be determined based on the time elapsed since the start of use of the multiple solid silica particles 41.

[0110] Furthermore, if the measurement time by the concentration measurement unit 50 is extremely short and the controller 3 can immediately determine whether the measured concentration in the etching liquid that has reached the measurement position 12a is equal to or less than the threshold value, there is no need to allow the etching liquid to flow into the return pipe 60 until the measurement time has elapsed. In this case, if the measured concentration in the etching liquid that has reached the measurement position 12a is equal to or less than the threshold value, the etching liquid is sent to the etching liquid tank 20 without flowing into the return pipe 60.

[0111] Furthermore, the concentration measurement unit 50 may be, for example, an ICP optical emission spectrometer (ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy). When the concentration measurement unit 50 is, for example, an ICP optical emission spectrometer, it is common that the ICP optical emission spectrometer is not provided in the exhaust pipe 10 but is provided separately from the substrate processing apparatus 1. In this case, the etching liquid in the exhaust pipe 10 is sampled, and the silicon concentration in the etching liquid is measured using the ICP optical emission spectrometer provided separately from the substrate processing apparatus 1. However, a configuration in which the ICP optical emission spectrometer is provided in the exhaust pipe 10 may also be used.

[0112] Furthermore, the upstream end of the return pipe 60 and the upstream end of the circulation pipe 120 do not need to be connected to the measurement position 12a, but may be connected to a position in the downstream discharge pipe 12 downstream of the measurement position 12a and upstream of the downstream discharge valve 17. The modifications shown in FIGS. 8 and 9 can also be applied to the second to fourth embodiments.

[0113] In addition, various modifications can be made within the scope of the claims. [Explanation of symbols]

[0114] 1: Substrate processing equipment 1: Substrate processing equipment 1P: Substrate processing equipment 1Q: Substrate processing equipment 1R: Substrate processing equipment 2: Etching processing section 10: Discharge piping (discharge flow path) 11: Upstream discharge piping (upstream discharge flow path) 12: Downstream discharge piping (downstream discharge flow path) 12a: Measurement position 17: Downstream discharge valve (downstream discharge flow path opening and closing unit) 20: Etching solution tank 30: Supply pipe (supply flow path) 40: Solid silica unit 40A: 1st solid silica unit 40B: Second solid silica unit 41: Solid silica 41a: Corner 42: Silica storage section 43: Cylindrical space 44: Liquid storage section 50: Concentration measurement unit 60: Return piping (return flow path) 61: Return valve (return flow path opening and closing valve) 70: Branch piping (branch flow path) 71: Branch valve (branch flow path opening and closing valve) 100: Cooling unit 101: Coolant supply pipe (coolant supply flow path) 104: Coolant discharge pipe (coolant discharge flow path) 120: Circulation piping (circulation flow path) 121: Circulation valve (circulation flow path opening and closing unit) EL: Etching solution W: Substrate X: Axial direction

Claims

1. an etching processing unit that etches the substrate with an etching solution; a discharge flow path for discharging the etching solution from the etching processing unit; a solid silica unit provided in the discharge flow path, the solid silica unit includes a plurality of solid silica particles and a silica container that contains the plurality of solid silica particles and allows an etching solution to pass therethrough; the silica storage portion has a cylindrical space filled with a plurality of the solid silica particles, the discharge flow path includes an upstream discharge flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream discharge flow path connected to the other end of the cylindrical space in the axial direction, The substrate processing apparatus, wherein the particle size of the solid silica is 1 mm or more and 10 mm or less.

2. The substrate processing apparatus according to claim 1 , wherein the solid silica has a grain shape with corners.

3. The substrate processing apparatus of claim 1 , wherein the solid silica has a spherical shape.

4. The substrate processing apparatus according to claim 2 , wherein the solid silica has a polyhedral shape or a pellet shape.

5. An etching processing unit that etches the substrate with an etching solution; a discharge flow path for discharging the etching solution from the etching processing unit; a solid silica unit provided in the discharge flow path; a concentration measuring unit for detecting a silicon concentration in the etching solution at a predetermined measurement position downstream of the solid silica unit in the discharge flow path; an etching solution tank for storing an etching solution; a discharge flow path opening / closing unit that is provided downstream of the measurement position in the discharge flow path and opens and closes the discharge flow path; the solid silica unit includes a plurality of solid silica particles and a silica container that contains the plurality of solid silica particles and allows an etching solution to pass therethrough; the silica storage portion has a cylindrical space filled with a plurality of the solid silica particles, The substrate processing apparatus, wherein the discharge flow path includes an upstream discharge flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream discharge flow path connected to the other end of the cylindrical space in the axial direction.

6. a return flow path connected to the discharge flow path at the same position as the measurement position or at a position downstream of the measurement position, and returning the etching solution to the discharge flow path upstream of the solid silica unit; The substrate processing apparatus according to claim 5 , further comprising a return flow path opening and closing unit that opens and closes the return flow path.

7. a branch flow path that branches off from the discharge flow path downstream of a return position where the etching solution returns from the return flow path and upstream of the solid silica unit, and is connected to the discharge flow path downstream of the solid silica unit and upstream of the measurement position; The substrate processing apparatus according to claim 6 , further comprising a branch flow path opening / closing unit that opens and closes the branch flow path.

8. a circulation flow path that is connected to the discharge flow path at the same position as the measurement position or downstream of the measurement position, and downstream of the solid silica unit and upstream of the measurement position, and that circulates the etching solution; The substrate processing apparatus according to claim 6 , further comprising a circulation channel opening and closing unit that opens and closes the circulation channel.

9. 9. The substrate processing apparatus according to claim 5, further comprising a supply passage that supplies the etching liquid in the etching liquid tank to the etching processing section.

10. An etching processing unit that etches the substrate with an etching solution; a discharge flow path for discharging the etching solution from the etching processing unit; a solid silica unit provided in the discharge flow path, the solid silica unit includes a plurality of solid silica particles and a silica container that contains the plurality of solid silica particles and allows an etching solution to pass therethrough; the silica storage portion has a cylindrical space filled with a plurality of the solid silica particles, the discharge flow path includes an upstream discharge flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream discharge flow path connected to the other end of the cylindrical space in the axial direction, a plurality of the solid silica units are provided, A substrate processing apparatus, wherein a plurality of the solid silica units are arranged in series in the discharge flow path.

11. An etching processing unit that etches the substrate with an etching solution; a discharge flow path for discharging the etching solution from the etching processing unit; a solid silica unit provided in the discharge flow path, the solid silica unit includes a plurality of solid silica particles and a silica container that contains the plurality of solid silica particles and allows an etching solution to pass therethrough; the silica storage portion has a cylindrical space filled with a plurality of the solid silica particles, the discharge flow path includes an upstream discharge flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream discharge flow path connected to the other end of the cylindrical space in the axial direction, a plurality of the solid silica units are provided, A substrate processing apparatus, wherein a plurality of the solid silica units are arranged in parallel in the discharge flow path.

12. an etching step of etching the substrate with an etching solution in an etching processing unit; a discharge step of discharging the etching solution from the etching treatment section to a discharge flow path; a solid silica passing step of passing the etching solution discharged into the discharge flow path in the discharge step through a silica storage section that stores a plurality of solid silica particles; the silica storage portion has a cylindrical space filled with a plurality of the solid silica particles, the discharge flow path includes an upstream discharge flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream discharge flow path connected to the other end of the cylindrical space in the axial direction, The substrate processing method, wherein the particle size of the solid silica is 1 mm or more and 10 mm or less.

13. An etching step of etching a substrate with an etching solution in an etching processing section; a discharge step of discharging the etching solution from the etching treatment section to a discharge flow path; a solid silica passing step of passing the etching solution discharged into the discharge flow path in the discharge step through a silica storage section that stores a plurality of solid silica particles; a concentration measuring step of measuring a silicon concentration in the etching solution that has passed through the silica containing section; a determining step of determining whether the silicon concentration measured in the concentration measuring step is equal to or less than a predetermined threshold value, the recovery step and the return step are selectively performed so that, when it is determined in the determination step that the silicon concentration measured in the concentration measurement step is equal to or less than the threshold value, a recovery step is performed in which the etching liquid that has passed through the silica containing section is recovered in an etching liquid tank, and when it is determined in the determination step that the silicon concentration measured in the concentration measurement step is not equal to or less than the threshold value, a return step is performed in which the etching liquid is returned to a side upstream of the silica containing section in the discharge flow path, the silica storage portion has a cylindrical space filled with a plurality of the solid silica particles, A substrate processing method, wherein the exhaust flow path includes an upstream exhaust flow path connected to one end of the cylindrical space in the axial direction of the cylindrical space, and a downstream exhaust flow path connected to the other end of the cylindrical space in the axial direction.

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