Removal device, substrate processing apparatus and removal method

Abstract

To provide a removal device, a substrate processing apparatus and a removal method which can efficiently remove a silicic acid compound from processing liquid.SOLUTION: In a substrate processing system, a removal device 3 comprises a silicic acid capturing part 34, an introduction part 32 and a discharge part 35. The silicic acid capturing part 34 captures a silicic acid compound included in used processing liquid used in substrate processing. The introduction part 32 introduces the used processing liquid to the silicic acid capturing part. The discharge part 35 discharges the used processing liquid processed by the silicic acid capturing part. The silicic acid capturing part 34 includes a porous member 51 and a pH adjustment mechanism 52. The porous member has a hole diameter through which the silicic acid compound included in the used processing liquid can pass. The pH adjustment mechanism increases a pH value of the used processing liquid that is in contact with the porous member.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a technique has been known in a substrate processing system in which a nitride film formed on a substrate is etched by immersing the substrate in an aqueous solution of phosphoric acid (H3PO4). Also, a technique has been known in which a used aqueous solution of phosphoric acid is reused by removing silicate compounds from the used aqueous solution of phosphoric acid in the etching process (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-6623 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique capable of efficiently removing silicic acid compounds from a treatment solution. [Means for solving the problem]

[0005] A removal device according to one embodiment of the present disclosure includes a silicic acid capture unit, an introduction unit, and a discharge unit. The silicic acid capture unit captures silicic acid compounds contained in a used processing liquid used in substrate processing. The introduction unit introduces the used processing liquid into the silicic acid capture unit. The discharge unit discharges the used processing liquid treated in the silicic acid capture unit. The silicic acid capture unit also includes a porous member and a pH adjustment mechanism. The porous member has a pore size that allows the silicic acid compounds contained in the used processing liquid to pass through. The pH adjustment mechanism increases the pH value of the used processing liquid that comes into contact with the porous member. [Effects of the Invention]

[0006] According to the present disclosure, silicic acid compounds can be efficiently removed from a treatment liquid. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic block diagram showing an example of the configuration of a substrate processing system according to each embodiment. [Figure 2] FIG. 2 is a schematic block diagram showing an example of the configuration of an etching processing apparatus according to each embodiment. [Figure 3] FIG. 3 is a schematic block diagram showing an example of the configuration of the silicic acid trapping unit according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining an example of the trapping process of the silicic acid trapping unit according to the first embodiment. [Figure 5] FIG. 5 is a diagram for explaining an example of the trapping process of the silicic acid trapping unit according to the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining another example of the trapping process of the silicic acid trapping unit according to the first embodiment. [Figure 7] FIG. 7 is a diagram for explaining another example of the trapping process of the silicic acid trapping unit according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining another example of the trapping process of the silicic acid trapping unit according to the first embodiment. [Figure 9] FIG. 9 is a schematic block diagram showing a configuration example of a silicic acid trapping unit according to Modification 1 of the first embodiment. [Figure 10] FIG. 10 is a schematic block diagram showing the configuration of a silicic acid trapping unit according to the second modification of the first embodiment. [Figure 11] FIG. 11 is a schematic block diagram showing an example of the configuration of a silicic acid trapping unit according to the second embodiment. [Figure 12] FIG. 12 is a diagram for explaining the configuration of the silicic acid trapping unit and the trapping process according to the second embodiment. [Figure 13]FIG. 13 is a diagram for explaining the configuration of the silicic acid trapping unit and the trapping process according to the second embodiment. [Figure 14] FIG. 14 is a schematic block diagram showing a configuration example of a silicic acid trapping unit according to Modification 3 of the first embodiment. [Figure 15] FIG. 15 is a schematic block diagram showing a configuration example of a silicic acid trapping unit according to the fourth modification of the first embodiment. [Figure 16] FIG. 16 is a schematic block diagram showing another configuration example of the substrate processing system according to each embodiment. [Figure 17] FIG. 17 is a flowchart illustrating an example of a procedure of the removal process executed by the removal device according to the first embodiment. [Figure 18] FIG. 18 is a flowchart illustrating an example of a procedure of the removal process executed by the removal device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of a removal apparatus, a substrate processing apparatus, and a removal method disclosed herein will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments described below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from reality. Furthermore, the dimensional relationships and ratios may differ between the drawings.

[0009] BACKGROUND ART Conventionally, in a substrate processing system, a technique is known in which a nitride film formed on a substrate is etched by immersing the substrate in an aqueous solution of phosphoric acid (H3PO4).

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

[0011] Furthermore, in the etching process of the silicon nitride film, silicic acid compounds (hereinafter also simply referred to as "silicic acid") such as polysiloxane generated from the silicon nitride film dissolve in the etching solution.

[0012] In the etching process of the silicon nitride film, if the concentration of silicic acid in the etching solution becomes high, problems such as precipitation of silicic acid compounds on the silicon oxide film may occur.

[0013] Therefore, in order to achieve both stable etching and a reduction in the amount of phosphoric acid aqueous solution discarded in such an etching process, a technique is known in which the used phosphoric acid aqueous solution is reused by removing silicate compounds from the used phosphoric acid aqueous solution.

[0014] On the other hand, the above-mentioned conventional techniques have room for further improvement in the efficiency of removing silicic acid compounds. Therefore, it is desired to realize a technique that can overcome the above-mentioned problems and efficiently remove silicic acid compounds from a treatment liquid such as an aqueous phosphoric acid solution.

[0015] <Configuration of substrate processing system> First, the configuration of a substrate processing system 1 according to each embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic block diagram showing an example of the configuration of a substrate processing system 1 according to each embodiment, and Figure 2 is a schematic block diagram showing an example of the configuration of an etching processing apparatus 2 according to each embodiment. The substrate processing system 1 is an example of a substrate processing apparatus.

[0016] As shown in FIG. 1, the substrate processing system 1 includes an etching processing device 2, a removal device 3, and a control device 4. The etching processing device 2 is an example of a substrate processing unit, and performs an etching process on a substrate W with an etching liquid L1. The etching liquid L1 is an example of a processing liquid. The removal device 3 regenerates the used etching liquid L1 (hereinafter also referred to as used liquid L2) used in the etching processing device 2.

[0017] The substrate W includes, for example, a wafer made of silicon or the like, and a silicon oxide film and a silicon nitride film formed on the surface of the wafer. The silicon oxide film and the silicon nitride film are, for example, repeatedly stacked alternately to form a laminated film. The laminated film has, for example, through holes penetrating in the thickness direction.

[0018] The etching solution L1 is, for example, a processing solution containing phosphoric acid. The etching solution L1 penetrates into the through holes of the laminated film and selectively etches and removes the silicon nitride film out of the silicon oxide film and the silicon nitride film.

[0019] 2, the etching processing apparatus 2 is, for example, a batch type that simultaneously processes a plurality of substrates W with an etching liquid L1, and has a processing tank 11. The processing tank 11 stores the etching liquid L1, and the plurality of substrates W are immersed in the etching liquid L1 inside the processing tank 11.

[0020] The processing tank 11 is, for example, a double tank, and includes an inner tank 11a and an outer tank 11b. The inner tank 11a stores an etching solution L1. The outer tank 11b collects the etching solution L1 that overflows from the inner tank 11a. A plurality of substrates W are immersed in the etching solution L1 inside the inner tank 11a and are processed by the etching solution L1.

[0021] The etching treatment device 2 has a circulation path 12. The circulation path 12 sends the etching solution L1 taken out from the outer bath 11b to the inner bath 11a. The etching treatment device 2 also has a pump 13, a heater 14, and a filter 15 along the circulation path 12.

[0022] The pump 13 forms a circulating flow of the etching solution L1 that is sent from the outer tank 11b to the inner tank 11a via the circulation path 12. The etching solution L1 also overflows from the opening of the inner tank 11a and flows back into the outer tank 11b. In this way, a circulating flow of the etching solution L1 is formed in the etching processing device 2. That is, this circulating flow is formed in the outer tank 11b, the circulation path 12, and the inner tank 11a.

[0023] The heater 14 adjusts the temperature of the etching solution L1 circulating through the circulation path 12. The temperature of the etching solution L1 is set to, for example, the boiling point of the etching solution L1. The filter 15 collects particles contained in the etching solution L1 circulating through the circulation path 12 and filters the etching solution L1.

[0024] The etching treatment device 2 also has a horizontal pipe 16 inside the inner tank 11a. The horizontal pipe 16 supplies the etching liquid L1 sent from the circulation path 12 into the inner tank 11a. The horizontal pipes 16 extend in the Y-axis direction, and a plurality of the horizontal pipes 16 are provided at intervals in the X-axis direction.

[0025] The horizontal pipes 16 each have a plurality of discharge ports (not shown) spaced apart in the longitudinal direction, and each of the discharge ports discharges the etching solution L1 directly upward, thereby forming a curtain-like upward flow in the inner tank 11a.

[0026] The etching processing apparatus 2 also has a substrate holding unit 17. The substrate holding unit 17 moves up and down between a standby position and a processing position while holding a plurality of substrates W at intervals in the Y-axis direction. The standby position is a position where the plurality of substrates W are transferred to a transport device (not shown), and is set above the processing position. The processing position is a position where the plurality of substrates W are immersed in the etching solution L1.

[0027] The substrate holder 17 receives the unprocessed substrate W from the transport device at the standby position, then descends to the processing position, and after a predetermined time has elapsed, ascends again to the standby position and hands over the processed substrate W to the transport device at the standby position.

[0028] The selectivity of the etching process in this etching device 2 depends on the concentration of silicic acid in the etching solution L1, and the higher the concentration of silicic acid, the better the selectivity. On the other hand, if the concentration of silicic acid exceeds the saturation concentration, silicic acid compounds S (see FIG. 4) will precipitate on the silicon oxide film.

[0029] Furthermore, as the etching process of the substrate W progresses, the silicic acid compound S is eluted from the substrate W into the etching solution L1, and the silicic acid concentration in the etching solution L1 gradually increases. Therefore, in the etching processing device 2, a replacement process of the etching solution L1 is performed to maintain the silicic acid concentration within an allowable range.

[0030] Specifically, used etching liquid L1 having a high silicic acid concentration (i.e., used liquid L2) is discharged from the etching processing device 2 to the outside, and etching liquid L1 having a lower silicic acid concentration than this used liquid L2 is supplied to the etching processing device 2 from the outside.

[0031] Therefore, the etching treatment device 2 has a liquid supply unit 18 and a liquid drainage unit 19. The liquid supply unit 18 supplies an etching liquid L1 with a low concentration of silicic acid to the etching treatment device 2 from the outside.

[0032] The liquid supply unit 18 supplies the etching liquid L1, for example, regenerated by the removal device 3, to the etching processing device 2. Note that the liquid supply unit 18 may supply the etching processing device 2 with unused etching liquid L1.

[0033] The liquid supply unit 18 has, for example, an on-off valve and a flow rate controller, and by opening the on-off valve, supplies the etching liquid L1 with a low silicic acid concentration to the outer tank 11b of the processing tank 11. The supply amount is controlled by the flow rate controller.

[0034] The drainage section 19 discharges the used liquid L2 to the outside from the etching treatment device 2. The drainage section 19 may discharge the used liquid L2 to the outside from the bottom of the inner tank 11a as shown in FIG. 2, or may discharge the used liquid L2 to the outside from the middle of the circulation path 12.

[0035] The drainage unit 19 has, for example, an on-off valve and a flow rate controller, and by opening the on-off valve, the used liquid L2 is discharged to the outside of the etching processing apparatus 2. The amount of discharge is controlled by the flow rate controller. At least a portion of the used liquid L2 discharged by the drainage unit 19 is sent to the removal device 3.

[0036] Returning to the explanation of Figure 1, the removal device 3 removes the silicic acid compound S (see Figure 4) from the used liquid L2 (see Figure 3) used in the etching treatment device 2. As a result, in the removal device 3, the used liquid L2 with a high silicic acid concentration is regenerated into the etching liquid L1 with a low silicic acid concentration.

[0037] The removal device 3 includes a first buffer tank 31, an introduction section 32, a switching valve 33, a silicic acid capture section 34, a discharge section 35, a filter 36, a concentration sensor 37, a switching valve 38, a circulation path 39, a second buffer tank 40, and an additive supply section 41. The switching valve 33 is an example of a branch section.

[0038] The first buffer tank 31 stores the used liquid L2 supplied from the drainage part 19 via the first liquid transfer path 20.

[0039] The introduction section 32 introduces the used liquid L2 stored in the first buffer tank 31 into the silicic acid capture section 34. The introduction section 32 is composed of, for example, a pipe 32a (see FIG. 3) connecting the first buffer tank 31 and the silicic acid capture section 34, and a pump (not shown) provided on the pipe 32a.

[0040] The introduction section 32 is also provided with a switching valve 33. The switching valve 33 selects either the liquid supplied from the first buffer tank 31 on the upstream side or the liquid supplied from the circulation path 39, and allows the selected liquid to flow into the silicic acid capture section 34 on the downstream side.

[0041] The silicic acid trapping section 34 traps the silicic acid compound S contained in the used liquid L2 that has been used in substrate processing in the etching processing apparatus 2. Details of the silicic acid trapping section 34 will be described later.

[0042] The discharge unit 35 discharges the used liquid L2 from which the silicic acid compound S has been removed in the silicic acid capture unit 34. The discharge unit 35 is composed of, for example, a pipe 35a (see FIG. 3) connecting the silicic acid capture unit 34 and the second buffer tank 40, and a pump (not shown) provided on the pipe 35a.

[0043] The discharge section 35 is also provided with a filter 36, a concentration sensor 37, and a switching valve 38. The filter 36 collects particles contained in the used liquid L2 flowing through the discharge section 35, and filters the used liquid L2.

[0044] The concentration sensor 37 detects the silicic acid concentration of the used liquid L2 flowing through the discharge section 35. The concentration sensor 37 is also connected to the control device 4, and a signal generated by the concentration sensor 37 is sent to the control device 4.

[0045] The switching valve 38 selects either the downstream circulation path 39 or the second buffer tank 40, and allows the liquid supplied from the upstream silicic acid capture unit 34 to flow through the selected path. The circulation path 39 is connected between the switching valve 38 and the switching valve 33.

[0046] The second buffer tank 40 stores the used liquid L2 (i.e., the regenerated etching liquid L1) after the removal process of the silicic acid compound S has been completed. The second buffer tank 40 is connected to the liquid supply unit 18 via a second liquid transfer path 21. The second liquid transfer path 21 transfers the etching liquid L1 regenerated by the removal device 3 to the etching treatment device 2.

[0047] The removal device 3 may have an additive supply unit 41 that supplies an additive to the regenerated etching solution L1 stored in the second buffer tank 40. Such an additive may be a common additive, such as a precipitation inhibitor that suppresses silica precipitation during processing of the substrate W, or a concentration adjuster that adjusts the silicic acid concentration.

[0048] 1, the additive supply unit 41 is connected to the second buffer tank 40, but the additive supply unit 41 may be connected to a third buffer tank (not shown). Such a third buffer tank is provided midway along the second liquid transfer path 21 that connects the second buffer tank 40 and the etching treatment device 2. Furthermore, the additive supply unit 41 may be omitted.

[0049] The substrate processing system 1 also includes a control device 4. The control device 4 controls the operation of each unit in the substrate processing system 1. The control device 4 is, for example, a computer, and includes a control unit 5 and a storage unit 6. The storage unit 6 stores programs for controlling various processes such as substrate processing and removal processing. The control unit 5 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the storage unit 6.

[0050] Such a program may be recorded on a computer-readable recording medium and installed from that recording medium into the storage unit 6 of the control device 4. Examples of computer-readable recording media include hard disks (HDs), flexible disks (FDs), compact disks (CDs), magnetic optical disks (MOs), and memory cards.

[0051] <Details of the Silica Capture Unit (First Embodiment)> Next, the silicic acid trapping unit 34 according to the first embodiment will be described in detail with reference to Figures 3 to 10. Figure 3 is a schematic block diagram showing an example of the configuration of the silicic acid trapping unit 34 according to the first embodiment.

[0052] 3, the silicic acid capture unit 34 according to the first embodiment includes a pipe 50, a porous member 51, and a pH adjustment mechanism 52. The pH adjustment mechanism 52 includes a cathode 53, an anode 54, and a power source 55. The cathode 53 is an example of an electrode.

[0053] The pipe 50 is, for example, a pipe formed integrally with the pipe 32a of the inlet 32 ​​and the pipe 35a of the outlet 35. The porous member 51 is made of a porous material having a pore size that allows the silicic acid compound S (see FIG. 4) contained in the used liquid L2 to pass through. The porous member 51 is, for example, arranged in a cylindrical shape along the inner wall of the pipe 50.

[0054] The porous member 51 is made of, for example, a metal (such as tungsten or a noble metal), a semiconductor (such as silicon or germanium), a metal oxide, carbon, a polymer material (such as polyaniline), etc. The pore diameter of the porous member 51 is preferably, for example, 1 nm to 100 nm, and more preferably 2 nm to 10 nm.

[0055] The cathode 53 of the pH adjustment mechanism 52 is in contact with the porous member 51. The cathode 53 is arranged, for example, in a cylindrical shape so as to be in contact with the outer wall of the cylindrically arranged porous member 51. The anode 54 is arranged in the vicinity of the porous member 51 at a distance from the porous member 51. The anode 54 is also arranged so as to be in contact with the used liquid L2 flowing inside the pipe 50.

[0056] The power supply 55 applies a given negative voltage to the cathode 53 and a given positive voltage to the anode 54. The negative voltage applied to the cathode 53 is, for example, −0.5 (V) to −10 (V).

[0057] Next, a description will be given of the removal process of the silicic acid compound S by the silicic acid trapping section 34. Figures 4 and 5 are diagrams for explaining an example of the trapping process by the silicic acid trapping section 34 according to the first embodiment.

[0058] 4, first, the control unit 5 (see FIG. 1) operates the power supply 55 (see FIG. 3) to apply a given negative voltage to the cathode 53 (step S01). Then, a chemical reaction shown in the following formula (1) occurs in the used liquid L2 that permeates the inside of the porous member 51 adjacent to the cathode 53, and the pH value of the used liquid L2 increases (step S02). 2H+ +2e - →H2···(1)

[0059] As a result, the used liquid L2 that permeates the inside of the porous member 51 changes from weakly acidic to neutral or weakly alkaline. Furthermore, when the used liquid L2 changes to neutral or weakly alkaline, the silicate compounds S contained in the used liquid L2 polymerize with each other and gradually increase in particle size.

[0060] That is, in the first embodiment, by applying a negative voltage to the cathode 53, the silicic acid compound S is polymerized inside the porous member 51 (step S03). Then, as shown in Fig. 5, the control unit 5 captures the silicic acid compound S, which has polymerized with each other and whose particle size is larger than the pore size of the porous member 51, in the porous member 51 (step S04).

[0061] In this way, in the first embodiment, the pH adjustment mechanism 52 increases the pH value of the used liquid L2 that comes into contact with the porous member 51, thereby promoting the polymerization reaction of the silicate compound S, and thereby capturing the polymerized silicate compound S in the porous member 51.

[0062] As a result, in the first embodiment, the silicic acid compound S can be efficiently removed from the used liquid L2.

[0063] In the first embodiment, the pH adjustment mechanism 52 preferably includes a cathode 53 and a power source 55. This allows the used liquid L2 that permeates the inside of the porous member 51 to be efficiently changed to neutral or weakly alkaline, thereby further promoting the polymerization reaction of the silicate compound S.

[0064] Therefore, according to the first embodiment, the silicic acid compound S can be removed more efficiently from the used liquid L2.

[0065] 3 shows the case where pH adjustment mechanism 52 has cathode 53 and power supply 55, the present disclosure is not limited to such an example. For example, pH adjustment mechanism 52 may have a chemical solution supply unit that causes an alkaline chemical solution to permeate the inside of porous member 51.

[0066] This also makes it possible to change the used liquid L2 that permeates the inside of the porous member 51 to a neutral or weakly alkaline state, thereby making it possible to efficiently remove the silicic acid compound S from the used liquid L2.

[0067] In the first embodiment, the porous member 51 is preferably made of a conductive material. This allows the negative voltage applied to the cathode 53 to be directly transmitted to the porous member 51, thereby efficiently changing the used liquid L2 that permeates the inside of the porous member 51 to a neutral or weakly alkaline state.

[0068] Therefore, according to the first embodiment, the silicic acid compound S can be removed more efficiently from the used liquid L2.

[0069] In the present disclosure, when the porous member 51 is made of a conductive material, the cathode 53 may be omitted and a negative voltage may be applied directly to the porous member 51 from the power source 55. This also makes it possible to efficiently change the used liquid L2 that permeates the inside of the porous member 51 to a neutral or weakly alkaline state, thereby making it possible to more efficiently remove the silicate compound S from the used liquid L2.

[0070] 3, the porous member 51 may be disposed along the inner wall of the pipe 50 through which the used liquid L2 flows. This prevents the porous member 51 from interfering with the flow of the used liquid L2.

[0071] Therefore, according to the first embodiment, the frequency with which the silicate compound S in the used liquid L2 comes into contact with the porous member 51 can be increased, thereby making it possible to more efficiently remove the silicate compound S from the used liquid L2.

[0072] In addition, in the first embodiment, the control unit 5 controls the switching valve 33 and the switching valve 38 to return the used liquid L2, which has been treated to remove the silicic acid compound S, from the discharge unit 35 to the silicic acid capture unit 34 via the circulation path 39.

[0073] That is, in the first embodiment, the circulating flow formed by the discharge section 35, the circulation path 39, and the introduction section 32 may be used to repeatedly remove the silicic acid compound S from the used liquid L2 in the silicic acid trapping section 34.

[0074] At this time, the control unit 5 performs the removal process of the silicic acid compound S while measuring the silicic acid concentration in the circulating flow using the concentration sensor 37. When the silicic acid concentration becomes equal to or lower than a given threshold value, the control unit 5 determines that the removal process of the silicic acid compound S is completed, and controls the switching valve 38 to send the regenerated etching solution L1 in the circulating flow to the second buffer tank 40.

[0075] This increases the frequency with which the silicic acid compounds S in the used liquid L2 come into contact with the porous member 51, compared to when the used liquid L2 is retained in the silicic acid capture section 34 and the silicic acid compounds S are removed. Therefore, according to the first embodiment, the silicic acid compounds S can be removed from the used liquid L2 more efficiently.

[0076] 4 and 5 show an example in which a constant negative voltage is applied to the cathode 53, but the present disclosure is not limited to such an example. Figures 6 to 8 are diagrams for explaining another example of the capture process of the silicic acid capture unit 34 according to the first embodiment.

[0077] In another example of the capture process described below, a pulsed negative voltage is applied to the cathode 53. First, as shown in FIG. 6, the control unit 5 (see FIG. 1) controls the power supply 55 (see FIG. 3) to apply a given negative voltage to the cathode 53 (step S11).

[0078] As a result, the area where the weakly acidic used liquid L2 has changed to neutral or weakly alkaline (hereinafter also referred to as the neutralized area N) increases (step S12). In the process of step S12, for example, the neutralized area N in the used liquid L2 increases from the surface of the cathode 53 to the area extending beyond the porous member 51.

[0079] Next, as shown in FIG. 7, the control unit 5 (see FIG. 1) controls the power supply 55 (see FIG. 3) to stop applying a given negative voltage to the cathode 53 (step S13). Then, the neutralization region N in the used liquid L2 decreases (step S14). In the process of step S14, for example, the neutralization region N in the used liquid L2 decreases to near the surface of the cathode 53.

[0080] That is, at this point, the vicinity of the surface of the porous member 51 is no longer the neutralized region N, and therefore the polymerization reaction of the silicic acid compound S is suppressed in the vicinity of the surface of the porous member 51. Therefore, the silicic acid compound S easily penetrates into the interior of the porous member 51 (step S15).

[0081] Next, as shown in Fig. 8, the control unit 5 (see Fig. 1) controls the power supply 55 (see Fig. 3) to apply a given negative voltage to the cathode 53 again (step S16). As a result, the neutralization region N in the used liquid L2 increases again (step S17).

[0082] Therefore, the control unit 5 can promote the polymerization reaction of the silicic acid compound S that has penetrated deep into the porous member 51, and can capture the polymerized silicic acid compound S even deep inside the porous member 51 (step S18).

[0083] 6 to 8, by applying a pulsed negative voltage to the cathode 53, the polymerized silicic acid compound S can be captured not only near the surface of the porous member 51 but also deep inside the porous member 51. Therefore, according to the first embodiment, the silicic acid compound S can be more efficiently removed from the used liquid L2.

[0084] 9 is a schematic block diagram showing a configuration example of the silicic acid trapping unit 34 according to Modification 1 of the first embodiment. As shown in Fig. 9, in the silicic acid trapping unit 34 of Modification 1, porous members 51 are arranged so as to intersect inside a pipe 50 through which the used liquid L2 flows. For example, in Modification 1, a mesh-like cathode 53 coated with the porous member 51 is arranged so as to block the inside of the pipe 50.

[0085] This increases the frequency with which the silicic acid compound S in the used liquid L2 comes into contact with the porous member 51. Therefore, according to this first modification, the silicic acid compound S can be removed from the used liquid L2 more efficiently.

[0086] 10 is a schematic block diagram showing a configuration example of the silicic acid trapping unit 34 according to Modification 2 of the first embodiment. As shown in Fig. 10, in the silicic acid trapping unit 34 of Modification 2, a porous member 51 is arranged in a coil shape along the inner wall of a pipe 50 through which the used liquid L2 flows. For example, in Modification 2, a coil-shaped cathode 53 coated with the porous member 51 is arranged along the inner wall of the pipe 50.

[0087] This increases the frequency with which the silicic acid compound S in the used liquid L2 comes into contact with the porous member 51. Therefore, according to Modification 2, the silicic acid compound S can be removed from the used liquid L2 more efficiently.

[0088] <Details of the Silica Capture Unit (Second Embodiment)> Next, the silicic acid trapping unit 34 according to the second embodiment will be described in detail with reference to Figures 11 to 13. Figure 11 is a schematic block diagram showing an example of the configuration of the silicic acid trapping unit 34 according to the second embodiment.

[0089] 11, the silicic acid capture unit 34 according to the second embodiment includes an expanded diameter section 60, an adsorbent 61, and filters 62 and 63. The expanded diameter section 60 is a section of the pipe 50 through which the used liquid L2 flows in the silicic acid capture unit 34, where the inner diameter is larger than that of the upstream and downstream sides.

[0090] The adsorbent 61 selectively adsorbs the silicic acid compound S (see FIG. 12) contained in the used liquid L2. The adsorbent 61 is arranged, for example, so as to block the inside of the expanded diameter portion 60. The filter 62 is arranged upstream of the adsorbent 61 inside the expanded diameter portion 60. The filter 63 is arranged downstream of the adsorbent 61 inside the expanded diameter portion 60.

[0091] In this way, by arranging the filters 62 and 63 on the upstream and downstream sides of the adsorbent 61, it is possible to prevent the adsorbent 61 from flowing out of the expanded diameter portion 60.

[0092] 12 and 13 are diagrams illustrating the configuration and capture process of the silicic acid capture unit 34 according to the second embodiment. As shown in Fig. 12, the adsorbent 61 has a base material 61a, a spacer 61b, and an alkoxysilyl group 61c.

[0093] The base material 61a is, for example, particulate or fibrous, and is made of resin, metal, metal oxide, etc. There is no particular limit to the particle size or fiber diameter of the base material 61a, and it can be from the nm order to the mm order.

[0094] The spacer 61b connects the surface of the base material 61a and the alkoxysilyl group 61c. If the surface of the base material 61a can be directly modified with the alkoxysilyl group 61c, the spacer 61b may be omitted.

[0095] The alkoxysilyl group 61c is -SiR n In this formula, R is a methoxy group (-OCH3) or an ethoxy group (-OCH2CH3), and n can be 1 to 3.

[0096] 12, the adsorbent 61 whose surface is modified with alkoxysilyl groups 61c is immersed in the used liquid L2 in the silicic acid capture unit 34. Then, as shown in FIG. 13, the alkoxysilyl groups 61c and the silicic acid compound S chemically react to form a covalent bond, and the silicic acid compound S is selectively adsorbed onto the adsorbent 61.

[0097] Therefore, according to the second embodiment, the silicic acid compound S can be efficiently removed from the used liquid L2.

[0098] <Modification of the silicic acid trapping unit> Next, various modifications in which the first embodiment is combined with the second embodiment will be described with reference to Fig. 14 and Fig. 15. Fig. 14 is a schematic block diagram showing an example of the configuration of a silicic acid trapping unit 34 according to Modification 3 of the first embodiment.

[0099] 14 , in this modification 3, the adsorbent 61 of the second embodiment is disposed inside a cylindrical porous member 51 that is disposed along the inner wall of a pipe 50. For example, the adsorbent 61 is disposed so as to fill the interior of the cylindrical porous member 51. In this modification 3, a negative voltage is applied from a power source 55 to a cathode 53 that is in contact with the porous member 51.

[0100] As a result, the silicic acid compounds S (see FIG. 4) can be captured by the porous member 51, and the silicic acid compounds S can also be captured by the adsorbent 61. Therefore, according to the third modification, the silicic acid compounds S can be more efficiently removed from the used liquid L2.

[0101] Fig. 15 is a schematic block diagram showing a configuration example of the silicic acid capture unit 34 according to Modification 4 of the first embodiment. As shown in Fig. 15, in Modification 4, the adsorbent 61 of the second embodiment is disposed inside the porous member 51 and near the surface of the cathode 53 that is in contact with the porous member 51.

[0102] As a result, the silicic acid compound S (see FIG. 4) can be captured by the porous member 51 in a region away from the cathode 53, and the silicic acid compound S can be captured by the adsorbent 61 in the vicinity of the surface of the cathode 53. Therefore, according to the fourth modification, the silicic acid compound S can be more efficiently removed from the used liquid L2.

[0103] In the present disclosure, the removal device 3 may be provided with a silicic acid trapping section 34 in which the silicic acid trapping section 34 of the first embodiment and the silicic acid trapping section 34 of the second embodiment are connected in series between the switching valve 33 (see FIG. 1) and the filter 36 (see FIG. 1). This also makes it possible to more efficiently remove the silicic acid compound S from the used liquid L2.

[0104] <Modification of removal device> Fig. 16 is a schematic block diagram showing another configuration example of the substrate processing system 1 according to each embodiment. In Fig. 16, the configuration of the removal apparatus 3 is different from the example in Fig. 1. Specifically, in the example in Fig. 16, a solution supply unit 43 and a solution discharge unit 47 are further provided in the removal apparatus 3.

[0105] The dissolving liquid supply unit 43 is connected to a switching valve 45 via a dissolving liquid supply path 44. The switching valve 45 is provided in the pipe 32a (see FIG. 3) of the introduction unit 32, and selects either the liquid supplied from the first buffer tank 31 on the upstream side or the liquid supplied from the dissolving liquid supply unit 43, and causes the selected liquid to flow into the silicic acid capture unit 34 on the downstream side.

[0106] The dissolving liquid supply unit 43 supplies a dissolving liquid capable of selectively dissolving the silicic acid compound S (see FIG. 4) to the silicic acid capture unit 34 via a switching valve 45 or the like. Such a dissolving liquid is, for example, a mixture of dilute hydrofluoric acid, dilute ammonia water, and DIW (deionized water). Note that the dissolving liquid of the present disclosure is not limited to the mixture of the above composition, and may have any composition as long as it can selectively dissolve the silicic acid compound S.

[0107] The dissolving liquid discharge part 47 is connected to a switching valve 46 provided upstream of the filter 36 in the discharge part 35, and discharges the liquid (e.g., dissolving liquid) supplied to the silicic acid capture part 34 to the drain part DR. The switching valve 46 selects either the downstream switching valve 38 or the dissolving liquid discharge part 47, and allows the liquid supplied from the upstream silicic acid capture part 34 to flow into the selected one.

[0108] Then, the control unit 5 (see Figure 1) supplies the dissolving liquid from the dissolving liquid supply unit 43 to the silicic acid capture unit 34 that has been used for a given time, and discharges the supplied dissolving liquid from the dissolving liquid discharge unit 47 to the drain unit DR.

[0109] This allows the silicic acid compound S captured by the silicic acid capture unit 34 to be selectively dissolved and removed, thereby regenerating the silicic acid capture unit 34. Therefore, according to the example of Fig. 16, the silicic acid capture unit 34 does not need to be disposed of, and the regeneration cost of the etching solution L1 can be reduced.

[0110] The removal device 3 according to the first embodiment includes a silicic acid trapping section 34, an introduction section 32, and a discharge section 35. The silicic acid trapping section 34 traps silicic acid compounds S contained in a used processing liquid (used liquid L2) that has been used in substrate processing. The introduction section 32 introduces the used processing liquid (used liquid L2) into the silicic acid trapping section 34. The discharge section 35 discharges the used processing liquid (used liquid L2) that has been treated in the silicic acid trapping section 34. The silicic acid trapping section 34 also includes a porous member 51 and a pH adjustment mechanism 52. The porous member 51 has a pore size that allows the silicic acid compounds S contained in the used processing liquid (used liquid L2) to pass through. The pH adjustment mechanism 52 increases the pH value of the used processing liquid (used liquid L2) that comes into contact with the porous member 51. This enables efficient removal of silicic acid compounds S from the used liquid L2.

[0111] In the removal device 3 according to the first embodiment, the pH adjustment mechanism 52 includes an electrode (cathode 53) in contact with the porous member 51 and a power source 55 that applies a negative voltage to the electrode (cathode 53). This allows the silicic acid compound S to be removed more efficiently from the used liquid L2.

[0112] The removal device 3 according to the first embodiment further includes a control unit 5 that controls each unit. The control unit 5 applies a pulsed negative voltage to the electrode (cathode 53) while maintaining the flow of the used treatment liquid (used liquid L2) through the silicic acid capture unit 34. This allows the silicic acid compound S to be removed more efficiently from the used liquid L2.

[0113] Furthermore, in the removal device 3 according to the first embodiment, the porous member 51 is made of a conductive material, which allows the silicic acid compound S to be removed from the used liquid L2 more efficiently.

[0114] In the removal device 3 according to the first embodiment, the porous member 51 is disposed along the inner wall of the pipe 50 through which the used treatment liquid (used liquid L2) flows. This allows the silicic acid compound S to be removed from the used liquid L2 more efficiently.

[0115] In the removal device 3 according to the first embodiment, the porous members 51 are arranged so as to intersect inside the pipe 50 through which the used treatment liquid (used liquid L2) flows. This allows the silicic acid compound S to be removed from the used liquid L2 more efficiently.

[0116] Furthermore, in the removal device 3 according to the first embodiment, the silicic acid trapping section 34 has an adsorbent 61 that selectively adsorbs the silicic acid compounds S. This allows the silicic acid compounds S to be removed more efficiently from the used liquid L2.

[0117] The removal apparatus 3 according to the second embodiment includes a silicic acid trapping section 34, an introduction section 32, and a discharge section 35. The silicic acid trapping section 34 traps silicic acid compounds S contained in a used processing liquid (used liquid L2) that has been used in substrate processing. The introduction section 32 introduces the used processing liquid (used liquid L2) into the silicic acid trapping section 34. The discharge section 35 discharges the used processing liquid (used liquid L2) that has been treated in the silicic acid trapping section 34. The silicic acid trapping section 34 also includes an adsorbent 61 that selectively adsorbs silicic acid compounds S. This allows the silicic acid compounds S to be efficiently removed from the used liquid L2.

[0118] In the removal device 3 according to each embodiment, the discharge section 35 has a branching section (switching valve 38). The removal device 3 according to each embodiment further includes a circulation path 39 that returns the used treatment liquid (used liquid L2) from the branching section (switching valve 38) to the silicic acid capture section 34. This allows the silicic acid compound S to be removed more efficiently from the used liquid L2.

[0119] Moreover, the removal device 3 according to each embodiment further includes a dissolving liquid supply unit 43 that supplies a dissolving liquid for dissolving the silicic acid compound S to the silicic acid capturing unit 34, and a dissolving liquid discharge unit 47 that discharges the dissolving liquid supplied to the silicic acid capturing unit 34. This reduces the cost of regenerating the etching liquid L1.

[0120] Furthermore, the substrate processing apparatus (substrate processing system 1) according to each embodiment includes a substrate processing unit (etching processing apparatus 2), a first liquid transfer path 20, the removal apparatus 3 described above, and a second liquid transfer path 21. The substrate processing unit (etching processing apparatus 2) processes a substrate W with a processing liquid (etching liquid L1). The first liquid transfer path 20 transfers the used processing liquid (used liquid L2) from the substrate processing unit (etching processing apparatus 2) to the introduction unit 32. The second liquid transfer path 21 transfers the used processing liquid (used liquid L2) that has been treated in the silicic acid capture unit 34 from the discharge unit 35 to the substrate processing unit (etching processing apparatus 2). This makes it possible to achieve etching of the substrate W that achieves both stable etching and reduced waste of phosphoric acid aqueous solution.

[0121] <Removal procedure> Next, the procedure of the removal process according to each embodiment will be described with reference to Fig. 17 and Fig. 18. Fig. 17 is a flowchart showing an example of the procedure of the removal process executed by the removal device 3 according to the first embodiment.

[0122] In the removal process according to the first embodiment, first, the control unit 5 causes the used liquid L2 used in the etching treatment device 2 to flow through the silicic acid trapping unit 34 (step S101).

[0123] Next, the control unit 5 operates the pH adjustment mechanism 52 to increase the pH value of the used liquid L2 flowing through the silicic acid capture unit 34 (step S102). Then, the control unit 5 polymerizes the silicic acid compound S inside the porous member 51, and captures the polymerized silicic acid compound S in the porous member 51 (step S103).

[0124] Next, the control unit 5 controls the switching valves 33, 38, etc. to circulate the used liquid L2 treated in the silicic acid trapping unit 34 (step S104), and the removal process in the silicic acid trapping unit 34 is repeated.

[0125] Next, the control unit 5 determines whether the silicic acid concentration of the circulating used liquid L2 is equal to or less than a given threshold value (step S105). If the silicic acid concentration of the circulating used liquid L2 is equal to or less than the given threshold value (step S105, Yes), the control unit 5 controls the switching valve 38 and the like to send the used liquid L2, for which the removal process has been completed, to the second buffer tank 40 (step S106). This completes the series of removal processes.

[0126] On the other hand, if the silicic acid concentration of the circulating used liquid L2 is not equal to or less than the given threshold value (No in step S105), the process returns to step S102.

[0127] FIG. 18 is a flowchart showing an example of the procedure of the removal process executed by the removal device 3 according to the second embodiment.

[0128] In the removal process according to the second embodiment, first, the control unit 5 causes the used liquid L2 used in the etching processing device 2 to flow through the silicic acid capturing unit 34 (step S201). Then, the control unit 5 causes the adsorbent 61 to capture the silicic acid compound S contained in the used liquid L2 (step S202).

[0129] Next, the control unit 5 controls the switching valves 33, 38, etc. to circulate the used liquid L2 treated in the silicic acid trapping unit 34 (step S203), and the removal process in the silicic acid trapping unit 34 is repeated.

[0130] Next, the control unit 5 determines whether the silicic acid concentration of the circulating used liquid L2 is equal to or less than a given threshold value (step S204). If the silicic acid concentration of the circulating used liquid L2 is equal to or less than the given threshold value (step S204, Yes), the control unit 5 controls the switching valve 38 and the like to send the used liquid L2, for which the removal process has been completed, to the second buffer tank 40 (step S205). This completes the series of removal processes.

[0131] On the other hand, if the silicic acid concentration of the circulating used liquid L2 is not equal to or less than the given threshold value (No in step S204), the process returns to step S202.

[0132] The removal method according to the first embodiment includes a flowing step (step S101), a polymerization step (step S102), and a capture step (step S103). In the flowing step (step S101), a used processing liquid (used liquid L2) used in substrate processing is passed through a porous member 51 having a pore size that allows the silicic acid compound S to pass through. In the polymerization step (step S102), the pH value of the used processing liquid (used liquid L2) in contact with the porous member 51 is increased, thereby polymerizing the silicic acid compound S contained in the used processing liquid (used liquid L2). In the capture step (step S103), the polymerized silicic acid compound S is captured by the porous member 51. This allows the silicic acid compound S to be efficiently removed from the used liquid L2.

[0133] In the removal method according to the first embodiment, the polymerization step (step S102) applies a pulsed negative voltage to the electrode (cathode 53) in contact with the porous member 51 while maintaining the flow of the used processing liquid (used liquid L2) through the porous member 51. This makes it possible to more efficiently remove the silicic acid compound S from the used liquid L2.

[0134] Moreover, the removal method according to the first embodiment further includes a step of supplying a dissolving liquid that dissolves the silicic acid compound S to remove the silicic acid compound S captured in the porous member 51. This reduces the cost of regenerating the etching liquid L1.

[0135] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit thereof. For example, in the above embodiments, an example is shown in which an etching solution L1 containing an aqueous phosphoric acid solution is used as the treatment solution, but the composition of the treatment solution is not limited to this example, and any treatment solution may be used as long as it is a treatment solution that requires removal of the silicic acid compound S.

[0136] Furthermore, in each of the above embodiments, the device structure formed on the surface of the substrate W is a stacked silicon nitride film and a silicon oxide film, but the device structure formed on the surface of the substrate W is not limited to such an example.

[0137] In addition, although the etching processing apparatus 2 is a batch-type substrate processing apparatus in each of the above embodiments, the etching processing apparatus 2 may be a single-wafer type substrate processing apparatus. The single-wafer type substrate processing apparatus includes, for example, a spin chuck that holds the substrate W horizontally and a nozzle that supplies the etching liquid L1 to the substrate W rotated by the spin chuck.

[0138] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0139] 1. Substrate processing system (an example of a substrate processing device) 2. Etching treatment equipment (an example of a substrate treatment equipment) 3 Removal device 5. Control section 20 First liquid transfer path 21 Second liquid transfer path 32 Introduction 34 Silica capture unit 35 Discharge section 38 Switching valve (an example of a branching section) 39 Circulation path 43 Solution supply section 47 Solution discharge part 50 Piping 51 Porous materials 52 pH adjustment mechanism 53 Cathode (an example of an electrode) 55 Power supply 60 Expanded diameter part 61 Adsorbents L1 Etching solution (an example of a processing solution) L2 Used liquid (an example of used processing liquid) S Silicate compounds W substrate

Claims

1. a silicic acid capturing unit configured to capture silicic acid compounds contained in a used processing solution used in substrate processing; an introduction section for introducing the used treatment liquid into the silicic acid capture section; a discharge section for discharging the used treatment liquid that has been treated in the silicic acid capture section; Equipped with The silicic acid capturing part is a porous member having a pore size that allows the passage of a silicic acid compound contained in the used treatment liquid; a pH adjusting mechanism for increasing the pH value of the used treatment liquid that comes into contact with the porous member; A removal device having:

2. The pH adjusting mechanism is an electrode in contact with the porous member; a power source that applies a negative voltage to the electrode; have The removal device of claim 1 .

3. Further, a control unit for controlling each unit is provided. The control unit applies a pulsed negative voltage to the electrode while maintaining the flow of the used treatment liquid through the silicic acid capture unit. The removal device of claim 2 .

4. The porous member is made of a conductive material. The removal device according to any one of claims 1 to 3.

5. The porous member is disposed along the inner wall of a pipe through which the used processing liquid flows. The removal device according to any one of claims 1 to 4.

6. The porous member is disposed so as to intersect inside the pipe through which the used processing liquid flows. The removal device according to any one of claims 1 to 4.

7. The silicic acid capturing section has an adsorbent that selectively adsorbs silicic acid compounds. The removal device according to any one of claims 1 to 6.

8. The discharge section has a branch section, a circulation path for returning the used treatment liquid from the branching section to the silicic acid capturing section. The removal device according to any one of claims 1 to 7.

9. a dissolving solution supplying section for supplying a dissolving solution for selectively dissolving a silicic acid compound to the silicic acid capturing section; a dissolution liquid discharge section that discharges the dissolution liquid supplied to the silicic acid capture section; Further equipped The removal device according to any one of claims 1 to 8.

10. a substrate processing unit for processing substrates with a processing liquid; a first liquid transfer path that transfers the used processing liquid from the substrate processing unit to the introduction part; A removal device according to any one of claims 1 to 9; a second liquid transfer path that transfers the used processing liquid that has been treated in the silicic acid capture unit from the discharge unit to the substrate processing unit; A substrate processing apparatus comprising:

11. a step of passing a used processing solution used in substrate processing through the inside of a porous member having a pore size that allows a silicate compound to pass through; increasing the pH value of the used treatment liquid that comes into contact with the porous member to polymerize a silicate compound contained in the used treatment liquid; capturing the polymerized silicic acid compound with the porous member; A removal method including:

12. The polymerization step includes applying a pulsed negative voltage to an electrode in contact with the porous member while maintaining the flow of the used treatment liquid through the porous member. The removal method according to claim 11.

13. and further comprising a step of supplying a dissolving liquid for dissolving the silicic acid compound to remove the silicic acid compound trapped in the porous member. The removal method according to claim 11 or 12.

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