Substrate processing apparatus and substrate processing method

Abstract

A waste liquid is simply reused as a treatment liquid containing sulfuric acid and an aqueous hydrogen peroxide solution. The substrate processing apparatus includes: a nozzle that supplies a first sulfuric acid-containing liquid and an aqueous hydrogen peroxide solution as a processing liquid to a substrate; a first tank for storing a first sulfuric acid-containing liquid supplied to the nozzle; an electrolysis path for generating a second sulfuric acid-containing liquid by electrolyzing a waste liquid, which is a processing liquid after processing the substrate; a concentration reduction device for reducing the concentration of peroxydisulfuric acid in the second sulfuric acid-containing liquid to generate a first sulfuric acid-containing liquid; and a supply path that supplies the first sulfuric acid-containing liquid to the first tank.

Description

Technical Field

[0001] The present invention relates to a technology for processing substrates. Substrates targeted for processing (hereinafter referred to as "substrate processing") include, for example, semiconductor wafers, glass substrates for liquid crystal displays (LCDs), substrates for flat panel displays (FPDs) such as organic EL (electroluminescence) displays, substrates for optical disks, magnetic disks, magneto-optical disks, glass substrates for photomasks, ceramic substrates, substrates for field emission displays (FEDs), and substrates for solar cells. Background Art

[0002] As a treatment liquid used for substrate treatment, a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), commonly known as SPM (Sulfuric Acid-Hydrogen Peroxide Mixture), is well known. SPM generates oxidizing power by mixing sulfuric acid and hydrogen peroxide, and is used, for example, to remove resist formed on the substrate surface.

[0003] The hydrogen peroxide solution contained in the SPM decomposes into water (H2O) during substrate processing. The concentration of sulfuric acid in the treatment liquid after substrate processing (hereinafter referred to as "waste liquid") is lower than that in the treatment liquid before substrate processing.

[0004] It is known to distill a waste liquid by increasing its temperature or pressurizing it, or by performing either of these methods, and reuse it as a treatment liquid (for example, disclosed in Patent Documents 1 and 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-47857

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-80048 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] There is a problem that increasing the temperature and pressurizing the waste liquid for distillation for reuse places a heavy burden on the equipment and requires a long time.

[0011] In view of the above problems, the present disclosure discloses a technology for simply recycling waste liquid into a treatment liquid containing sulfuric acid and an aqueous hydrogen peroxide solution.

[0012] Technical means to solve the problem

[0013] A first embodiment of a substrate processing apparatus according to the present invention uses a processing liquid containing sulfuric acid and an aqueous hydrogen peroxide solution to process a substrate, wherein the apparatus comprises: a nozzle for supplying a first sulfuric acid-containing liquid and an aqueous hydrogen peroxide solution as the processing liquid to the substrate; a first tank for storing the first sulfuric acid-containing liquid supplied to the nozzle; an electrolysis path for electrolyzing the processing liquid, i.e., waste liquid, after the substrate has been processed; a concentration reducing device for reducing the concentration of peroxydisulfuric acid in the second sulfuric acid-containing liquid to produce the first sulfuric acid-containing liquid; and a supply path for supplying the first sulfuric acid-containing liquid to the first tank.

[0014] According to a second aspect of the substrate processing apparatus of the present invention, in the first aspect, the concentration reducing device includes a first heater.

[0015] A third aspect of the substrate processing apparatus of the present invention, in the first or second aspect, is characterized in that the electrolysis path comprises: an electrolysis device for electrolysis; and a concentration meter for measuring the concentration of sulfuric acid, peroxymonosulfuric acid, and peroxydisulfuric acid, which are liquids flowing in the electrolysis device.

[0016] A fourth embodiment of the substrate processing apparatus of the present invention, in the first embodiment, the second embodiment or the third embodiment, further comprises a second tank, the second tank being supplied with the waste liquid and storing a third sulfuric acid-containing liquid, the third sulfuric acid-containing liquid comprising at least any one of the waste liquid, the first sulfuric acid-containing liquid, and the second sulfuric acid-containing liquid, the third sulfuric acid-containing liquid circulating between the second tank, the electrolysis path, and the concentration reducing device.

[0017] According to a fifth aspect of the substrate processing apparatus of the present invention, in the first aspect, the second aspect, the third aspect, or the fourth aspect, the supply path includes a second heater.

[0018] A sixth aspect of the substrate processing apparatus of the present invention is that, in the first, second, third, fourth, or fifth aspect, the nozzle mixes the first sulfuric acid-containing liquid with an aqueous hydrogen peroxide solution and supplies the processing liquid to the substrate.

[0019] The substrate processing method of the present invention uses a processing liquid containing sulfuric acid and an aqueous hydrogen peroxide solution to process a substrate, wherein the substrate processing method includes: a step of supplying a first sulfuric acid-containing liquid and an aqueous hydrogen peroxide solution as the processing liquid to the substrate; a step of electrolyzing the processing liquid, i.e., waste liquid, after the substrate has been processed to generate a second sulfuric acid-containing liquid; and a step of reducing the concentration of peroxydisulfuric acid in the second sulfuric acid-containing liquid to generate the first sulfuric acid-containing liquid.

[0020] Effects of the Invention

[0021] According to the first aspect of the substrate processing apparatus of the present invention, waste liquid can be easily reused as a processing liquid containing sulfuric acid and an aqueous hydrogen peroxide solution.

[0022] The second way helps in the deactivation of peroxydisulfuric acid.

[0023] A third approach helps estimate the concentration of water in the liquid flowing in the electrolysis device.

[0024] The fourth mode facilitates the regeneration process of obtaining the first sulfuric acid-containing liquid from the waste liquid.

[0025] The fifth aspect contributes to the liquid temperature maintenance treatment for adjusting the first sulfur-containing liquid to a temperature suitable for storage in the first tank.

[0026] The sixth aspect facilitates the production of a treatment liquid using the first sulfuric acid-containing liquid.

[0027] According to the substrate processing method of the present invention, waste liquid can be easily reused as a processing liquid containing sulfuric acid and an aqueous hydrogen peroxide solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a block diagram schematically showing the structure of the substrate processing apparatus of the present invention.

[0029] Figure 2 It is a schematic diagram illustrating the structure of the supply recovery unit.

[0030] Figure 3 It is a schematic diagram illustrating the configuration of a processing unit.

[0031] Figure 4 It is a schematic diagram schematically illustrating a processing unit and associated structures.

[0032] Figure 5 It is a cross-sectional view illustrating the internal structure of the nozzle.

[0033] Figure 6 It is a schematic diagram illustrating the structure of the discharge unit.

[0034] Figure 7 It is a schematic diagram illustrating the structure of the regeneration section.

[0035] Figure 8 This is a block diagram conceptually illustrating the configuration of a control unit.

[0036] Figure 9 This is a flow chart illustrating a process for regenerating sulfuric acid from waste liquid as the first sulfur-acid-containing liquid. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments will be described with reference to the accompanying drawings. In the following embodiments, detailed features are shown for the purpose of explaining the technology, but these are merely examples and are not necessarily all necessary features for implementing the embodiments.

[0038] The accompanying drawings are schematic diagrams, and for ease of explanation, structures may be omitted or simplified as appropriate in the accompanying drawings. In addition, the sizes and positions of the structures shown in the different drawings may not be accurately described and may be changed as appropriate. In addition, in drawings such as top views that are not cross-sectional views, hatching may sometimes be indicated to facilitate understanding of the contents of the embodiments.

[0039] In the drawings, when pipes are depicted as intersecting in a triangular or T-shape, unless otherwise specified, this indicates that the three pipes depicted as straight lines are interconnected. In the drawings, when pipes are depicted as intersecting in a quadrilateral or cross shape, unless otherwise specified, this indicates that the two pipes depicted as straight lines that pass through the intersection are not interconnected.

[0040] In the drawings, arrows attached to lines depicted as pipes indicate the direction of fluid flow.

[0041] In the following description, the same components are labeled with the same reference numerals and have the same names and functions, so detailed description thereof may be omitted to avoid duplication.

[0042] In the description described in the specification of the present application, when a certain structural member is described as “including”, “comprising”, or “having”, it is not an exclusive expression excluding the presence of other structural members unless otherwise specified.

[0043] In the descriptions recorded in the specification of this application, although ordinal numbers such as "first" or "second" are sometimes used, these terms are used to facilitate easy understanding of the contents of the implementation methods, and the contents of the implementation methods are not limited to the order that can be generated by these ordinal numbers.

[0044] In the descriptions recorded in the specification of this application, even if there are cases where terms are used that refer to specific positions or directions such as "up", "down", "left", "right", "side", "bottom", "front" or "back", these terms are used to facilitate easy understanding of the contents of the implementation method, and the implementation method has nothing to do with the position or direction during actual implementation.

[0045] In the description of this application, when references are made to "the upper surface of..." or "the lower surface of...", this includes not only the upper surface or lower surface of the structural member itself, but also states where other structural members are formed on the upper or lower surface of the structural member. That is, for example, when reference is made to "B provided on the upper surface of A," another structural member "C" may be provided between A and B.

[0046] <1. Overview of Substrate Processing Apparatus 1 >

[0047] Reference Figures 1 to 8 , the substrate processing apparatus 1 of the present invention is described. Figure 1 It is a block diagram schematically showing the structure of the substrate processing apparatus 1 according to the present invention.

[0048] The substrate processing apparatus 1 includes a supply and recovery unit 3 , a discharge unit 5 , a processing unit 6 , a regeneration unit 7 , and a control unit 90 .

[0049] <1-1. Supply and Recovery Section 3>

[0050] Figure 2 This is a schematic diagram illustrating the structure of the supply and recovery unit 3. The supply and recovery unit 3 has the function of supplying and recovering the first sulfuric acid-containing liquid to and from the processing unit 6. The processing unit 6 performs substrate processing. The first sulfuric acid-containing liquid is a liquid containing sulfuric acid, and may contain either or both peroxymonosulfuric acid (H2SO5) and peroxydisulfuric acid (H2S2O8). As described below, the concentration of peroxydisulfuric acid in the first sulfuric acid-containing liquid is preferably low.

[0051] The supply recovery unit 3 includes a supply tank 10 , supply pipes 100 and 220 , circulation pipes 102 and 110 , a drain pipe 162 , valves 12A, 100A, 102A, and 162A, a flow meter 112 , a pump 114 , a heater 116 , a thermometer 117 , and a filter 119 .

[0052] The supply tank 10 functions as a first tank for storing the first sulfur-containing liquid.

[0053] Sulfuric acid regenerated by the regeneration unit 7 (hereinafter also referred to as "regenerated sulfuric acid") flows through the supply pipe 100. A valve 100A is provided in the supply pipe 100 to adjust the flow rate of the regenerated sulfuric acid flowing through the supply pipe 100 under the control of the controller 90.

[0054] Sulfuric acid supplied from the sulfuric acid supply source 12 flows through the supply pipe 220. A valve 12A is provided in the supply pipe 220 to adjust the flow rate of the sulfuric acid flowing through the supply pipe 220 under the control of the controller 90. Figure 1Although the sulfuric acid supply source 12 is provided outside the substrate processing apparatus 1 as an example, it may be provided inside the substrate processing apparatus 1 .

[0055] The first sulfur-acid-containing liquid is supplied as regenerated sulfuric acid from the supply pipe 100 to the supply tank 10 , and sulfuric acid is supplied from the supply pipe 220 to the supply tank 10 .

[0056] The circulation pipe 102 circulates the first sulfuric acid-containing liquid between the circulation pipe 102 and the supply tank 10. The supply pipe group 106G communicates with the circulation pipe 102, and the circulation pipe 102 also supplies the first sulfuric acid-containing liquid to the processing unit 6 via the supply pipe group 106G.

[0057] The valve 102A, the flow meter 112 , the pump 114 , the heater 116 , the thermometer 117 , and the filter 119 are provided in series on the circulation pipe 102 .

[0058] Thermometer 117 measures the temperature of the first sulfuric acid-containing liquid flowing in circulation pipe 102. Heater 116 heats the first sulfuric acid-containing liquid so that the temperature measured by thermometer 117 reaches, for example, 120°C. This temperature adjustment is performed under the control of controller 90.

[0059] The filter 119 removes foreign matter such as particles from the first sulfur-containing liquid flowing through the circulation pipe 102 .

[0060] Pump 114 pressurizes the first sulfuric acid-containing liquid in circulation pipe 102 from the bottom of supply tank 10 to the opposite side of supply tank 10. This pressurization causes the first sulfuric acid-containing liquid to flow in circulation pipe 102 from the bottom of supply tank 10 to the liquid level of the first sulfuric acid-containing liquid.

[0061] The control unit 90 refers to the processing schedule to monitor the substrate processing performed by the processing unit 6. The control unit 90 controls the valve 102A to adjust the flow rate of the first sulfuric acid-containing liquid flowing through the circulation pipe 102 so that the flow rate of the first sulfuric acid-containing liquid measured by the flow meter 112 is sufficient for the substrate processing.

[0062] The return piping group 108G is connected to the circulation piping 110. The first sulfuric acid-containing liquid supplied from the supply piping group 106G but not used for substrate processing flows into the return piping group 108G. The first sulfuric acid-containing liquid flows from the processing section 6 through the return piping group 108G into the circulation piping 110. The first sulfuric acid-containing liquid flowing into the circulation piping 110 is supplied to the supply tank 10, for example, to the liquid level of the first sulfuric acid-containing liquid stored in the supply tank 10. In this manner, the first sulfuric acid-containing liquid is recovered from the processing section 6 to the supply recovery section 3.

[0063] The first sulfur-containing liquid is supplied to the supply tank 10 from the circulation pipes 102 and 110 .

[0064] Drain pipe 162 has the function of discharging the first sulfuric acid-containing liquid from supply tank 10. A valve 162A is provided on drain pipe 162 to adjust the flow rate of the first sulfuric acid-containing liquid flowing through drain pipe 162 under the control of controller 90. The first sulfuric acid-containing liquid discharged from supply tank 10 via drain pipe 162 is supplied to discharge unit 5.

[0065] <1-2. Processing Unit 6>

[0066] Figure 3 is a schematic diagram illustrating the structure of the processing unit 6. The processing unit 6 has a plurality of ( Figure 3 In the example, there are 6) processing units 600.

[0067] Each processing unit 600 includes valves 106A, 108A, 200A, and a nozzle 106B. Supply pipes 106, return pipes 108, and mixing pipes 200 lead to each processing unit 600. The plurality of supply pipes 106 constitute a supply pipe group 106G. The plurality of return pipes 108 constitute a return pipe group 108G.

[0068] The first sulfuric acid-containing liquid branches from the circulation pipe 102 and flows into the supply pipe 106 . A valve 106A is provided in the supply pipe 106 and adjusts the flow rate of the first sulfuric acid-containing liquid flowing in the supply pipe 106 under the control of the controller 90 .

[0069] The first sulfuric acid-containing liquid flows from nozzle 106B into return pipe 108. The first sulfuric acid-containing liquid flowing in return pipe 108 merges in circulation pipe 110 and flows into supply recovery unit 3. Valve 108A is provided in return pipe 108 to adjust the flow rate of the first sulfuric acid-containing liquid flowing in return pipe 108 under the control of controller 90.

[0070] Aqueous hydrogen peroxide solution is supplied from a source 13 (see Figure 1 ) flows into the mixing pipe 200. The valve 200A is provided in the mixing pipe 200 and adjusts the flow rate of the aqueous hydrogen peroxide solution flowing in the mixing pipe 200 under the control of the control unit 90.

[0071] Nozzle 106B supplies a first sulfuric acid-containing liquid and an aqueous hydrogen peroxide solution as treatment liquids to substrate W. Nozzle 106B is connected to supply pipe 106, return pipe 108, and mixing pipe 200. The first sulfuric acid-containing liquid is supplied from circulation pipe 102 to nozzle 106B via valve 106A and through supply pipe 106. Aqueous hydrogen peroxide solution is supplied from aqueous hydrogen peroxide supply source 13 to nozzle 106B via valve 200A and through mixing pipe 200. Nozzle 106B allows the first sulfuric acid-containing liquid supplied from supply pipe 106 but not used as treatment liquid to flow into circulation pipe 110 via valve 108A and through return pipe 108.

[0072] For example, the nozzle 106B mixes the first sulfuric acid-containing liquid and the hydrogen peroxide aqueous solution in the following manner and then flows into the return pipe 108 , or flows into the return pipe 108 without mixing.

[0073] exist Figure 3 The hydrogen peroxide aqueous solution supply source 13 is omitted. Figure 1 Although the case where it is provided outside the substrate processing apparatus 1 is illustrated in FIG, it may be provided inside the substrate processing apparatus 1 .

[0074] <1-3. Processing Unit 600>

[0075] Figure 4 FIG is a schematic diagram schematically illustrating the processing unit 600 and related structures. Figure 4 In the example, the configuration is shown in Figure 3 The illustrated example shows a structure of a treatment unit 600 on the side of a supply pipe 106 opposite to the circulation pipe 102 (downstream side with respect to the first sulfuric acid-containing liquid flowing in the circulation pipe 102; hereinafter referred to as "downstream side of the circulation pipe 102"). Figure 3 The processing unit 600 shown as an example is also arranged at a position downstream of the other supply pipe 106 than the circulation pipe 102. Figure 4 The illustrated structure is configured in the same manner.

[0076] The processing unit 600 includes a chamber 80 , a spin chuck 251 , and a processing shield 511 .

[0077] The chamber 80 is box-shaped with an internal space. The spin chuck 251 holds a substrate W in a horizontal position within the chamber 80 while rotating it about a vertical rotation axis Z1. For example, the spin chuck 251 holds the substrate W so that its center is located above the rotation axis Z1.

[0078] The processing shield 511 surrounds the spin chuck 251 and has a cylindrical shape extending along the rotation axis Z1.

[0079] The chamber 80 has a box-shaped wall 250A. An opening 250B is formed in the wall 250A. The substrate W is loaded into and unloaded from the chamber 80 through the opening 250B.

[0080] The chamber 80 has a movable baffle 250C. The opening 250B is opened and closed by the baffle 250C. The baffle 250C is moved to a closed position (in a position where it covers the opening 250B) by a baffle lifting mechanism (not shown). Figure 4 The opening position of the opening portion 250B (indicated by a dotted line in FIG. Figure 4 The solid line indicates the rise and fall between them.

[0081] The spin chuck 251 includes a spin base 251A, a plurality of chuck pins 251B, a rotation shaft 251C, and a rotation motor 251D.

[0082] The rotating base 251A is disk-shaped. A plurality of chuck pins 251B protrude upward from the outer periphery of the upper surface of the rotating base 251A. The plurality of chuck pins 251B grip or release the peripheral edge of the substrate W. The substrate W gripped by the chuck pins 251B is held horizontally on the rotating chuck 251, facing the rotating base 251A. A rotating shaft 251C extends downward from the center of the rotating base 251A. The rotating motor 251D rotates the rotating shaft 251C to rotate the substrate W gripped by the plurality of chuck pins 251B.

[0083] For example, the spin chuck 251 may be a vacuum adsorption type suction cup having a rotating base that vacuum adsorbs the lower surface of the substrate W, instead of holding the substrate W using a plurality of chuck pins 251B.

[0084] The nozzle 106B discharges the processing liquid toward a predetermined location (eg, the spin base 251A) inside the chamber 80. This discharge corresponds to supplying the processing liquid to the substrate W from the nozzle 106B when the substrate W is held on the spin base 251A.

[0085] The processing unit 600 may also be connected to a nozzle for spraying liquid for other purposes (for example, a nozzle for spraying other chemical liquids or a nozzle for spraying a flushing liquid).

[0086] The processing shield 511 is provided so as to surround the spin chuck 251. The processing shield 511 is vertically raised and lowered by a lifting mechanism (e.g., a motor or an air cylinder) not shown. The upper portion of the processing shield 511 is positioned above the substrate W held on the spin base 251A at its upper end (at the position of Figure 4 The substrate W is moved up and down between a position (shown as a processing shield 511 in the figure) and a position below the substrate W (not shown).

[0087] The waste liquid pipe 122 is provided at the bottom of the chamber 80 and inside the processing shield 511. Waste liquid scattered from the upper surface of the substrate W to the outside is caught by the inner side surface of the processing shield 511. The waste liquid caught by the processing shield 511 is appropriately discharged to the outside of the chamber 80 through the waste liquid pipe 122.

[0088] The recovery pipe 124 is connected to all the waste liquid pipes 122. The waste liquid flowing in the waste liquid pipe 122 is merged in the recovery pipe 124. The valve 122A is provided in the waste liquid pipe 122, and under the control of the control unit 90, the flow rate of the waste liquid flowing from the waste liquid pipe 122 to the recovery pipe 124 is adjusted. Figure 1 1 and 2 , the waste liquid pipes 122 of the respective processing units 600 are collectively shown as a waste liquid pipe group 122G.

[0089] The exhaust port 515 is provided on the side of the chamber 80. The atmosphere in the chamber 80 is appropriately exhausted to the outside of the chamber 80 through the exhaust port 515. The atmosphere in the processing shield 511 is exhausted by a shield exhaust mechanism (not shown).

[0090] For example, a piping space 8 is provided between the location where the supply recovery unit 3 is disposed and the space where the processing unit 6 is disposed. In the piping space 8, the supply piping group 106G is connected to the circulation piping 102, the return piping group 108G is connected to the circulation piping 110, and the waste liquid piping group 122G is connected to the recovery piping 124.

[0091] <1-4. Nozzle 106B>

[0092] Figure 5 It is a cross-sectional view illustrating the internal structure of the nozzle 106B.

[0093] The nozzle 106B includes a main body 36 , a valve body 37 , a pneumatic actuator 38 , and a discharge port 31 . The main body 36 includes a valve chamber 45 .

[0094] A flow path 35 for guiding the first sulfuric acid-containing liquid or the treatment liquid is formed in the main body 36. A valve body 37 opens and closes the flow path 35. A pneumatic actuator 38 advances and retracts the valve body 37 in the axial direction X1 to open and close the flow path 35. The flow path 35 on the side of the valve body 37 closer to the discharge port 31 communicates with the mixing pipe 200. The flow path 35 on the side of the mixing pipe 200 closer to the discharge port 31 functions as a flow path 35c for the treatment liquid. The flow path 35 farther from the discharge port 31 than the valve body 37 branches into flow paths 35a and 35b.

[0095] A pair of joints 48 are connected to the main body 36. One joint 48 is connected to a supply pipe 106, which communicates with the flow path 35a. The flow path 35a can also be considered a portion of the supply pipe 106. The other joint 48 is connected to a return pipe 108, which communicates with the flow path 35b. The flow path 35b can also be considered a portion of the return pipe 108.

[0096] The flow path 35a communicates with the supply pipe 106 and the valve chamber 45. The flow path 35b communicates with the return pipe 108 and the valve chamber 45. The flow path 35c communicates with the valve chamber 45 and the discharge port 31.

[0097] The pneumatic actuator 38 includes a cylinder 39, a piston 42, a spring 43, and a rod 44. The cylinder 39 and the valve chamber 45 are arranged along the axial direction X1. The cylinder 39 and the valve chamber 45 are separated by a partition wall 41. The valve body 37 moves forward and backward in the valve chamber 45.

[0098] The cylinder 39 is partitioned by a piston 42 into a front chamber on the partition wall 41 side and a rear chamber sandwiching the piston 42 in the axial direction X1. A spring 43 is installed between the piston 42 and the body 36 on the rear chamber side of the cylinder 39. The spring 43 presses the piston 42 toward the partition wall 41.

[0099] A pair of joints 47 are connected to the main body 36. One joint 47 is connected to a pipe (not shown) that transmits air pressure to the front chamber of the cylinder 39. The other joint 47 is connected to a pipe (not shown) that transmits air pressure to the rear chamber of the cylinder 39. Air pressure is transmitted to either the front chamber or the rear chamber of the cylinder 39 via these pipes and joints 47, thereby causing the piston 42 to advance and retract within the cylinder 39 along the axial direction X1.

[0100] The rod 44 extends through the partition wall 41 in the axial direction X1. One end of the rod 44 is connected to the piston 42. The other end of the rod 44 is connected to the valve body 37. The valve body 37 is, for example, in the shape of a disk, and its radial direction is perpendicular to the axial direction X1.

[0101] When the piston 42 moves forward and backward in the axial direction X1 in the cylinder 39 , the valve body 37 moves forward and backward in the axial direction X1 in the valve chamber 45 via the rod 44 .

[0102] The valve chamber 45 includes a valve seat surface 46. The valve seat surface 46 faces the partition wall 41 and has, for example, a circular annular shape perpendicular to the axial direction X1. The flow paths 35a and 35b are connected, for example, to the inner edge of the circular annular shape of the valve seat surface 46. When viewed along the forward and backward direction of the valve body 37 (axial direction X1), the flow path 35c is connected to the side of the valve chamber 45.

[0103] The main body 36 includes a cylindrical portion 49. The cylindrical portion 49 protrudes downward, and a discharge port 31 is formed at the lower end thereof. The mixing pipe 200 is introduced to the side of the cylindrical portion 49 and communicates with the flow path 35c.

[0104] When air pressure is not applied to any of the front chamber and the rear chamber of the cylinder 39, the air pressure actuator 38 is in an inoperative state. At this time, the piston 42 is pressed toward the valve chamber 45 by the spring 43 in the cylinder 39, and the valve body 37 contacts the valve seat surface 46 in the valve chamber 45. Due to this contact, the flow path 35 is closed between the flow paths 35a, 35b and the flow path 35c ( Figure 5 At this time, the piston 42 is located close to the partition wall 41.

[0105] At this time, the first sulfuric acid-containing liquid supplied from the supply tank 10 to the nozzle 106B through the supply pipe 106 and the flow path 35a returns to the supply tank 10 via the flow path 35b and the return pipe 108. Hereinafter, the state in which the first sulfuric acid-containing liquid flows from the supply pipe 106 to the return pipe 108 without being used as a treatment liquid in this manner is referred to as a "nozzle circulation state."

[0106] In the nozzle circulation state, the first sulfuric acid-containing liquid may flow between the circulation pipe 102 and the supply tank 10 without branching from the circulation pipe 102 to the supply pipe 106 .

[0107] When the nozzle circulation state is achieved, air pressure is transmitted to the front chamber of the cylinder 39, causing the piston 42 to retreat toward the rear chamber of the cylinder 39 against the pressing force of the spring 43. At this time, the valve body 37 moves away from the valve seat surface 46 within the valve chamber 45. As the valve body 37 moves away from the valve seat surface 46, the flow paths 35a and 35c communicate with the valve chamber 45, the flow path 35c communicates with the valve chamber 45, and the flow paths 35a and 35c communicate with the flow path 35c.

[0108] The first sulfuric acid-containing liquid supplied from supply tank 10 via supply pipe 106 and flow path 35a flows into flow path 35c. If valve 200A is opened at this time, the aqueous hydrogen peroxide solution mixes with the first sulfuric acid-containing liquid in flow path 35c from mixing pipe 200. As a result of this mixing, SPM, a treatment liquid, is ejected from ejection port 31. Hereinafter, the state in which the treatment liquid is ejected from ejection port 31 is referred to as the "ejection state."

[0109] When this ejection state is achieved, the air pressure supplied to the front chamber of cylinder 39 is stopped, or the air pressure supplied to the rear chamber of cylinder 39 is simultaneously stopped. As a result, piston 42 advances toward the front chamber of cylinder 39 under the pressing force of spring 43. At this point, valve body 37 contacts valve seat surface 46 within valve chamber 45. This contact of valve body 37 with valve seat surface 46 isolates flow paths 35a and 35b from valve chamber 45, isolates flow path 35c from valve chamber 45, and closes the gap between flow paths 35a and 35b and flow path 35c. In this way, the nozzle circulation state is achieved.

[0110] <1-5. Discharge Unit 5>

[0111] Figure 6 4 is a schematic diagram illustrating the structure of the discharge unit 5. The discharge unit 5 has a function of discharging liquid that is not necessary for the substrate processing apparatus 1 from the substrate processing apparatus 1. The discharge unit 5 includes a discharge liquid tank 40 and a valve 40A.

[0112] The first sulfuric acid-containing liquid is supplied from the supply recovery section 3, specifically, from the supply tank 10, to the discharge tank 40 via a drain pipe 162. Either or both of the second sulfuric acid-containing liquid and the waste liquid are supplied from the regeneration section 7 to the discharge tank 40 via a drain pipe 164. The second sulfuric acid-containing liquid will be described below in conjunction with the structure of the regeneration section 7.

[0113] The drain tank 40 stores any one of the first sulfuric acid-containing liquid, the second sulfuric acid-containing liquid, and waste liquid, or a mixture thereof. The liquid stored in the drain tank 40 is discharged to the outside of the substrate processing apparatus 1 via a valve 40A. The valve 40A adjusts the flow rate of the liquid discharged from the drain tank 40 under the control of the controller 90.

[0114] <1-6. Regeneration Section 7>

[0115] Figure 7 Schematic diagram illustrating the structure of the regeneration unit 7. The regeneration unit 7 includes recovery tanks 30A and 30B, valves 124A, 124B, 136A, and 136B, a pump 136, a recovery pipe 126, and a drain pipe 164.

[0116] Recovery piping 124 supplies waste liquid to recovery tank 30A via valve 124A and to recovery tank 30B via valve 124B. Recovery tanks 30A and 30B store waste liquid. Recovery tanks 30A and 30B supply waste liquid to pump 136 via valves 136A and 136B, respectively. Valves 136A and 136B regulate the flow rate of waste liquid supplied to pump 136 under the control of controller 90.

[0117] The waste liquid stored in the recovery tanks 30A and 30B is used for the following regeneration process. In the regeneration process, it is not desirable that the temperature of the waste liquid is high. When the first sulfuric acid-containing liquid is supplied to the nozzle 106B, it is preliminarily passed through the heater 116 (refer to Figure 2 ) increases in temperature, and the temperature of the waste liquid also increases. Recovery tanks 30A and 30B store the waste liquid and lower its temperature to, for example, below 60°C. Compared to using only one of recovery tanks 30A and 30B, alternating between recovery tanks 30A and 30B for storing the waste liquid and supplying it to the regeneration process improves the efficiency of both storage and supply. For example, when valve 124A is open, valve 136A is closed and valve 136B is open. For example, when valve 124A is closed, valve 136A is opened and valve 136B is closed.

[0118] The pump 136 sends both the waste liquid supplied from the recovery tank 30A via the valve 136A and the waste liquid supplied from the recovery tank 30B via the valve 136B to the recovery pipe 126 .

[0119] The regeneration section 7 includes regeneration tanks 20A and 20B, an electrolysis unit 21 , circulation pipes 128 and 130 , supply pipes 132 and 134 , and valves 126A and 126B.

[0120] Waste liquid is supplied from the recovery pipe 126 to the regeneration tank 20A via the valve 126A, and is supplied to the regeneration tank 20B via the valve 126B. Both valves 126A and 126B are controlled by the controller 90 to adjust the flow rate of the supplied waste liquid.

[0121] The regeneration tanks 20A and 20B function as a second tank for storing a third sulfuric acid-containing liquid. The third sulfuric acid-containing liquid includes one or more of the waste liquid, the first sulfuric acid-containing liquid, and the second sulfuric acid-containing liquid described below.

[0122] The circulation pipe 130 circulates the third sulfur-containing liquid between the regeneration tanks 20A and 20B and the electrolysis unit 21. The circulation pipe 128 circulates the third sulfur-containing liquid stored in the regeneration tanks 20A and 20B.

[0123] The supply pipe 132 supplies the first sulfuric acid-containing liquid from the regeneration tank 20A to the supply pipe 100 , and the supply pipe 134 supplies the first sulfuric acid-containing liquid from the regeneration tank 20B to the supply pipe 100 .

[0124] The circulation pipe 128 is provided with valves 14A, 14B, 128A, and 128B, a pump 140 , a heater 142 , a thermometer 143 , and a filter 144 .

[0125] Under the control of the controller 90 , the valve 128A adjusts the flow rate of the first sulfuric acid-containing liquid flowing from the regeneration tank 20A to the circulation pipe 128 , and the valve 128B adjusts the flow rate of the first sulfuric acid-containing liquid flowing from the regeneration tank 20B to the circulation pipe 128 .

[0126] Under the control of the controller 90 , the valve 14A adjusts the flow rate of the first sulfuric acid-containing liquid flowing from the circulation pipe 128 to the regeneration tank 20A, and the valve 14B adjusts the flow rate of the first sulfuric acid-containing liquid flowing from the circulation pipe 128 to the regeneration tank 20B.

[0127] Pump 140 transports the first sulfuric acid-containing liquid flowing through circulation pipe 128. Heater 142 heats the first sulfuric acid-containing liquid flowing through circulation pipe 128. Thermometer 143 measures the temperature of the first sulfuric acid-containing liquid flowing through circulation pipe 128. Filter 144 removes foreign matter, such as particles, from the first sulfuric acid-containing liquid flowing through circulation pipe 128.

[0128] The circulation pipe 130 is provided with valves 16A, 16B, 130A, and 130B, a concentration meter 146 , a pump 148 , a heater 150 , a thermometer 151 , and a filter 152 .

[0129] Under the control of the controller 90 , the valve 130A adjusts the flow rate of the third sulfuric acid-containing liquid flowing from the regeneration tank 20A to the circulation pipe 130 , and the valve 130B adjusts the flow rate of the third sulfuric acid-containing liquid flowing from the regeneration tank 20B to the circulation pipe 130 .

[0130] Under the control of the controller 90 , the valve 16A adjusts the flow rate of the third sulfuric acid-containing liquid flowing from the circulation pipe 130 to the regeneration tank 20A, and the valve 16B adjusts the flow rate of the third sulfuric acid-containing liquid flowing from the circulation pipe 130 to the regeneration tank 20B.

[0131] The concentration meter 146 measures the sulfuric acid concentration in the third sulfuric acid-containing liquid flowing in the circulation pipe 130. The "sulfuric acid concentration" mentioned here includes the concentration of sulfuric acid and the concentration of persulfuric acid (peroxymonosulfuric acid and peroxydisulfuric acid are both persulfuric acid).

[0132] Pump 148 conveys the third sulfuric acid-containing liquid flowing through circulation pipe 130. Heater 150 heats the third sulfuric acid-containing liquid flowing through circulation pipe 130. Thermometer 151 measures the temperature of the third sulfuric acid-containing liquid flowing through circulation pipe 130. Filter 152 removes foreign matter, such as particles, from the third sulfuric acid-containing liquid flowing through circulation pipe 130.

[0133] Under the control of the controller 90 , the valve 132A adjusts the flow rate of the third sulfuric acid-containing liquid flowing through the supply pipe 132 , and the valve 134A adjusts the flow rate of the third sulfuric acid-containing liquid flowing through the supply pipe 134 .

[0134] In the regeneration section 7 , a pump 154 ​​, a heater 156 , a thermometer 157 , and a filter 158 are provided in the supply pipe 100 .

[0135] The first sulfuric acid-containing liquid is supplied from the regeneration tank 20A via the supply pipe 132 and valve 132A to the pump 154, and the first sulfuric acid-containing liquid is supplied from the regeneration tank 20B via the supply pipe 134 and valve 134A to the pump 154. The pump 154 ​​conveys the first sulfuric acid-containing liquid flowing through the supply pipe 100.

[0136] Heater 156 heats the first sulfuric acid-containing liquid flowing through supply pipe 100. Thermometer 157 measures the temperature of the first sulfuric acid-containing liquid flowing through supply pipe 100. Filter 158 removes foreign matter, such as particles, from the first sulfuric acid-containing liquid flowing through supply pipe 100. Heater 156 controls the temperature of the first sulfuric acid-containing liquid flowing through supply pipe 100. This temperature control is performed under the control of control unit 90 using temperature measurements taken by thermometer 157.

[0137] The regeneration unit 7 includes valves 164A, 164B, 164C, and 164D. The regeneration tank 20A supplies the third sulfuric acid-containing liquid to the drain pipe 164 via valve 164A, and the regeneration tank 20B supplies the third sulfuric acid-containing liquid to the drain pipe 164 via valve 164B. The recovery tank 30A supplies waste liquid to the drain pipe 164 via valve 164C, and the recovery tank 30B supplies waste liquid to the drain pipe 164 via valve 164D. The flow rates adjusted by valves 164A, 164B, 164C, and 164D are controlled by the controller 90.

[0138] <1-7. Control Unit 90>

[0139] Figure 8 This is a block diagram conceptually illustrating the structure of the control unit 90. The control unit 90 can be formed by a common computer having circuits. Specifically, the control unit 90 includes a central processing unit (CPU) 91, a read-only memory (ROM) 92, a random access memory (RAM) 93, a storage device 94, an input unit 96, a display unit 97, and a communication unit 98, as well as a bus 95 interconnecting these.

[0140] ROM 92 stores basic programs. RAM 93 is used as a work area when CPU 91 performs predetermined processing. Storage device 94 is composed of a non-volatile storage device (e.g., a flash memory or a hard disk device). Input unit 96 is composed of, for example, various switches or a touch panel, and receives input setting instructions (e.g., processing procedures) from the operator. Display unit 97 is composed of, for example, a liquid crystal display device and a lamp, and displays various information under the control of CPU 91. Communication unit 98 has a data communication function via, for example, a local area network (LAN).

[0141] The storage device 94 is pre-set with multiple modes related to controlling the various components of the substrate processing apparatus 1. By having the CPU 91 execute a processing program 94P, one of these multiple modes is selected, and each component is controlled according to that mode. Furthermore, the processing program 94P can be stored on a storage medium. Using this storage medium, the processing program 94P can be installed in the control unit 90. Furthermore, some or all of the functions performed by the control unit 90 do not necessarily need to be implemented using software; they can also be implemented using dedicated hardware, such as logic circuits.

[0142] <2. Operation of Substrate Processing Apparatus 1 >

[0143] <2-1. Generation of treatment solution>

[0144] The substrate processing method performed using the substrate processing apparatus 1 includes the following steps: spraying a processing liquid onto a substrate W conveyed to the processing unit 600 to process the substrate; cleaning the processed substrate W; rotating and drying the cleaned substrate W; and unloading the dried substrate W from the processing unit 600. These steps are performed by the control unit 90 controlling the operation of various components of the substrate processing apparatus 1 (e.g., pumps, heaters, valves, or rotary motors).

[0145] The first sulfuric acid-containing liquid stored in the supply tank 10 is fed by the pump 114 and circulated between the circulation pipe 102 and the supply tank 10 (see Figure 2 The temperature of the first processing liquid in the circulation pipe 102 is adjusted by the heater 116 so that the temperature measured by the thermometer 117 becomes, for example, 120° C., and foreign matter such as particles is appropriately removed by the filter 119 .

[0146] The control unit 90 refers to the processing schedule to monitor the substrate processing being performed by the processing unit 600. The flow rate of the first sulfuric acid-containing liquid circulating in the circulation pipe 102 is adjusted by, for example, the opening degree of valve 102A so that the flow rate of the first sulfuric acid-containing liquid measured by flowmeter 112 is sufficient for the substrate processing. Valve 102A is adjusted under the control of the control unit 90.

[0147] By opening the valve 106A, the first sulfuric acid-containing liquid is supplied to the processing unit 600 via the circulation pipe 102 and the supply pipe 106 (see Figure 3 ).

[0148] Nozzle 106B is in nozzle circulation state ( Figure 5 When the valve body 37 is in contact with the valve seat surface 46, the valves 106A and 108A are opened, and the first sulfuric acid-containing liquid flows from the circulation pipe 102 through the supply pipe 106 and the return pipe 108 to the circulation pipe 110 and returns to the supply tank 10.

[0149] In this manner, the first sulfuric acid-containing liquid flows into nozzle 106B of supply pipe 106 and circulates. This helps suppress temperature fluctuations in the processing liquid caused by temperature differences between the various pipes and the processing liquid when the processing liquid is ejected from nozzle 106B to process substrates. For example, in the nozzle circulation state, the first sulfuric acid-containing liquid flowing through return pipe 108 to circulation pipe 110 is suppressed to the minimum flow rate sufficient to maintain the temperatures of the various pipes.

[0150] Nozzle 106B is in the ejection state ( Figure 5 When valve body 37 is separated from valve seat surface 46, valve 106A opens and valve 108A closes. The first sulfuric acid-containing liquid is supplied to flow path 35c. In the ejection state, valve 200A is also opened, and the hydrogen peroxide solution is also supplied to flow path 35c from mixing pipe 200. In flow path 35c, the first sulfuric acid-containing liquid and the hydrogen peroxide solution mix, and the treated liquid is ejected from ejection port 31. In this treated liquid, peroxymonosulfuric acid is generated as follows:

[0151] 2H2SO4+2H2O2→2H2SO5+2H2O

[0152] Therefore, the concentration of permonosulfuric acid in the first sulfuric acid-containing liquid is not required to be low.

[0153] The nozzle 106B helps to generate the treatment liquid using the first sulfuric acid-containing liquid. The treatment liquid ejected from the ejection port 31 reaches the upper surface of the substrate W, thereby performing substrate processing.

[0154] <2-2. Wastewater Recovery>

[0155] The processing liquid that has been discharged onto the substrate W and used for substrate processing flows as waste liquid through the open valve 122A to the waste liquid pipe 122. The waste liquid then flows to the recovery pipe 124 and is supplied to the recovery tanks 30A and 30B. This supply of waste liquid can be regarded as recovering the waste liquid from the processing unit 6 to the regeneration unit 7.

[0156] In the regeneration unit 7, a first sulfuric acid-containing liquid is obtained from the recovered waste liquid through the regeneration process described below. The regeneration process reduces the amount of sulfuric acid newly supplied to the substrate processing apparatus 1 and the amount of waste liquid discharged from the substrate processing apparatus 1, enabling more efficient use of resources and contributing to the realization of environmentally friendly technologies or production methods.

[0157] The waste liquid stored in the recovery tank 30A is transported in the recovery pipe 126 via the valve 136A by the pump 136, and the waste liquid stored in the recovery tank 30B is transported in the recovery pipe 126 via the valve 136B by the pump 136 (see Figure 7The waste liquid can be selectively delivered to the regeneration tank 20A by opening the valve 126A, delivered to the regeneration tank 20B by opening the valve 126B, or delivered to both by the pump 136.

[0158] <2-3. Generation of Second Sulfuric Acid-Containing Liquid>

[0159] The regeneration process can be explained by dividing it into the step of generating the second sulfur-acid-containing liquid from the waste liquid (hereinafter referred to as the "pre-step") and the step of generating the first sulfur-acid-containing liquid from the second sulfur-acid-containing liquid (hereinafter referred to as the "post-step"). The pre-step is the step of electrolyzing the waste liquid to generate the second sulfur-acid-containing liquid. The post-step is the step of reducing the concentration of peroxydisulfuric acid in the second sulfur-acid-containing liquid to generate the first sulfur-acid-containing liquid.

[0160] For simplicity of description, the case of regeneration treatment in the regeneration tank 20A will be described first. In the previous step or before the previous step, the valves 126A and 164A are adjusted to store waste liquid in an amount suitable for regeneration treatment in the regeneration tank 20A.

[0161] During the preceding and following steps, valves 128A and 14A are closed, and the third sulfuric acid-containing liquid stored in regeneration tank 20A does not flow into circulation pipe 128. Valve 132A is closed, and regeneration tank 20A is disconnected from supply pipe 100. Valve 164A is closed, and regeneration tank 20A is disconnected from drain pipe 164.

[0162] In the previous step, valves 16A and 130A are opened, pump 148 is operated, and the third sulfuric acid-containing liquid stored in regeneration tank 20A is supplied to electrolysis unit 21. Electrolysis unit 21 functions as an electrolysis device. As electrolysis unit 21 operates, the third sulfuric acid-containing liquid is electrolyzed by electrolysis unit 21 and stored in regeneration tank 20A.

[0163] By this electrolysis, water contained in the third sulfuric acid-containing liquid is decomposed into oxygen (O2) and hydrogen ions (H + ):

[0164] 2H2O→4H + +O2+4e -

[0165] The oxygen is exhausted as gas.

[0166] In this electrolysis, the peroxymonosulfuric acid contained in the third sulfuric acid-containing liquid is decomposed into oxygen, hydrogen ions and sulfate ions (SO4 2- ):

[0167] 2H2SO5→2SO4 2- +4H + +O2

[0168] The oxygen is exhausted as gas.

[0169] As water decomposes into oxygen and hydrogen ions, the water concentration in the third sulfuric acid-containing liquid decreases. The decrease in water concentration is detected as an increase in sulfuric acid concentration.

[0170] The second sulfuric acid-containing liquid has a lower water concentration than the waste liquid. By performing electrolysis, the proportion of the waste liquid in the third sulfuric acid-containing liquid stored in the regeneration tank 20A decreases, and the proportion of the second sulfuric acid-containing liquid increases.

[0171] The sulfuric acid concentration measured by the concentration meter 146 is greater than the specified value, which indicates that the water concentration in the third sulfuric acid-containing liquid is less than the desired upper limit. The concentration meter 146 helps estimate the water concentration in the liquid (e.g., the third sulfuric acid-containing liquid) flowing in the electrolysis unit 21.

[0172] For example, if the measured sulfuric acid concentration continuously falls within a specified range during the period required for the entire third sulfuric acid-containing liquid stored in the regeneration tank 20A to flow through the electrolysis unit 21, the measured sulfuric acid concentration can be considered to be the sulfuric acid concentration of the third sulfuric acid-containing liquid stored in the regeneration tank 20A. If the sulfuric acid concentration at this time exceeds the specified value, it can be estimated that the water concentration in the entire third sulfuric acid-containing liquid stored in the regeneration tank 20A is less than the desired upper limit. When the measured sulfuric acid concentration becomes greater than the specified value, the electrolysis is terminated, and the previous process is also terminated.

[0173] Using electrolysis to reduce the water concentration in wastewater helps reduce the burden on equipment and the time required compared to using distillation. It also allows for easy recycling of wastewater into a treatment solution containing sulfuric acid and aqueous hydrogen peroxide.

[0174] Before electrolysis begins, if the sulfuric acid concentration of the third sulfuric acid-containing liquid stored in regeneration tank 20A is above a predetermined value, electrolysis is not required. Thus, only when, for example, the sulfuric acid concentration is less than a first predetermined value, is electrolysis initiated, as determined to indicate that the water concentration has exceeded a desired upper limit. Furthermore, after electrolysis begins, electrolysis is terminated when the sulfuric acid concentration exceeds a second predetermined value that is greater than the first predetermined value. By terminating electrolysis, the preceding process is terminated.

[0175] After the electrolysis has ceased, sulfuric acid is obtained as follows:

[0176] 2SO4 2- +4H + →2H2SO4

[0177] Not with sulfate ions (SO4 2- ) bonded hydrogen ions (H + ) obtains electrons (e) from the cathode (not shown) of the electrolytic unit 21- ) and is discharged as hydrogen (H2).

[0178] In the previous step, the circulation pipe 130 and the electrolysis unit 21 function as an electrolysis path for electrolyzing the waste liquid to generate a second sulfuric acid-containing liquid. The degree of electrolysis can be estimated by the sulfuric acid concentration measured by the concentration meter 146, so the concentration meter 146 may also be included in the electrolysis path.

[0179] <2-4. Generation of the First Sulfuric Acid-Containing Liquid>

[0180] During electrolysis, the water concentration decreases while the peroxodisulfuric acid concentration increases. If the peroxodisulfuric acid concentration in the first sulfuric acid-containing liquid fluctuates, the peroxodisulfuric acid concentration in the treatment solution also fluctuates, potentially impairing substrate processing stability. A lower peroxodisulfuric acid concentration in the first sulfuric acid-containing liquid contributes to the stability of substrate processing using the treatment solution.

[0181] In the subsequent step, the electrolysis performed by the electrolysis unit 21 is stopped, and the second sulfuric acid-containing liquid flowing in the circulation pipe 130 is heated using the heater 150 .

[0182] In the subsequent step, valves 16A and 130A are opened, and pump 148 is operated. The second sulfuric acid-containing liquid stored in regeneration tank 20A in the previous step is supplied to heater 150. The second sulfuric acid-containing liquid is heated by heater 150 and stored in regeneration tank 20A. For example, heater 150 heats the second sulfuric acid-containing liquid flowing in circulation pipe 130 to a temperature of 90°C or higher. This temperature control is performed under the control of controller 90, using temperature measurement by thermometer 151.

[0183] By such heating, the peroxodisulfuric acid in the second sulfuric acid-containing liquid is decomposed, and sulfuric acid and peroxomonosulfuric acid are generated as shown below (the symbol "·" represents a free radical, and the same applies hereinafter).

[0184] S2O8 2- →2SO4 - ·

[0185] 2SO4 - +2H2O→2HSO4 2- +2OH·

[0186] 2HSO4 - +xH2O→2H2SO5+xH2

[0187] 2SO4 - +2H2O→2HSO4 2- +2OH·

[0188] This decomposition also manifests itself as the deactivation of peroxydisulfuric acid. The temperature at which this deactivation is achieved is also referred to as the deactivation temperature below. For example, the deactivation temperature is 90°C.

[0189] Peroxymonosulfuric acid is also generated in the treatment liquid. Therefore, the concentration of peroxymonosulfuric acid in the first sulfuric acid-containing liquid has little effect on the stability of substrate treatment performed using the treatment liquid.

[0190] The sulfuric acid concentration measured by concentration meter 146 does not distinguish between sulfuric acid, peroxymonosulfuric acid, and peroxydisulfuric acid. The heating time by heater 150 can be used to estimate, for example, the time it takes for the peroxydisulfuric acid concentration to fall below a desired upper limit. The post-process ends when its operating time exceeds a specified time. For example, the specified time is 5 minutes.

[0191] In the subsequent step, the circulation pipe 130 and the heater 150 function as a concentration reducing device for reducing the concentration of the second sulfur-containing liquid to generate the first sulfur-containing liquid.

[0192] Taking both the preceding and following steps into consideration, the third sulfur-containing liquid stored in the regeneration tank 20A circulates among the regeneration tank 20A, the electrolysis path, and the concentration reduction device. This circulation contributes to the regeneration process.

[0193] When the post-process is completed, that is, the regeneration treatment is completed, the temperature of the first sulfuric acid-containing liquid stored in the regeneration tank 20A is maintained at a temperature suitable for storage in the supply tank 10. This temperature maintenance is performed by circulation using the circulation pipe 128 and is sometimes temporarily referred to as "liquid temperature maintenance treatment" hereinafter.

[0194] Specifically, valves 16A, 130A, 126A, 132A, and 164A are closed, valves 14A and 128A are opened, and pump 140 and heater 142 are operated. The first sulfuric acid-containing liquid stored in regeneration tank 20A is pumped to circulation pipe 128 by pump 140 while being adjusted to a temperature of, for example, 60°C or higher by heater 142. This temperature control is performed under the control of control unit 90, using temperature measurement by thermometer 143.

[0195] The first sulfuric acid-containing liquid flowing through the circulation pipe 128 passes through the filter 144 to appropriately remove foreign matter such as particles, and is returned to the regeneration tank 20A via the valve 14A.

[0196] By circulating through the circulation pipe 128 , the regeneration treatment may be performed in the third sulfuric acid-containing liquid stored in the regeneration tank 20B while the liquid temperature of the first sulfuric acid-containing liquid stored in the regeneration tank 20A is being maintained.

[0197] Specifically, during the preceding and following steps, valves 128B and 14B are closed, and the third sulfuric acid-containing liquid stored in regeneration tank 20B does not flow into circulation pipe 128. Valve 134A is closed, and regeneration tank 20B is disconnected from supply pipe 100. Valve 164B is closed, and regeneration tank 20B is disconnected from drain pipe 164.

[0198] In the previous step, valves 16B and 130B are opened, pump 148 is activated, and the third sulfuric acid-containing liquid stored in regeneration tank 20B is supplied to electrolysis unit 21. Electrolysis unit 21 is activated, and the third sulfuric acid-containing liquid passes through electrolysis unit 21, undergoes electrolysis, and is stored in regeneration tank 20B. When the sulfuric acid concentration measured by concentration meter 146 exceeds a predetermined value, electrolysis is terminated, and the previous step also terminates.

[0199] In the subsequent step, electrolysis by electrolysis unit 21 is stopped, and heater 150 is used to heat the second sulfuric acid-containing liquid flowing in circulation pipe 130. In the subsequent step, valves 16B and 130B are opened, pump 148 is operated, and the second sulfuric acid-containing liquid stored in regeneration tank 20B in the previous step is supplied to heater 150. The second sulfuric acid-containing liquid is heated by heater 150 and stored in regeneration tank 20B. For example, heater 150 heats the second sulfuric acid-containing liquid flowing in circulation pipe 130 to a temperature of 90°C or higher.

[0200] The heating in the post-process deactivates the peroxydisulfuric acid in the manner described above. Heater 150 facilitates this deactivation. The longer the second sulfuric acid-containing liquid remains at the deactivation temperature, the greater the degree of deactivation. The degree of deactivation can be estimated by the time the second sulfuric acid-containing liquid remains at the deactivation temperature. The post-process terminates when its operating time exceeds a specified time.

[0201] Since the third sulfur-containing liquid is electrolyzed during the regeneration process, the circulation piping 130 or the circulation piping 130 together with the electrolysis unit 21, concentration meter 146, pump 148, heater 150, thermometer 151, and filter 152 provided in the circulation piping 130 is also temporarily referred to as the electrolysis system piping.

[0202] Since the temperature of the first sulfuric acid-containing liquid is adjusted during the liquid temperature maintaining process, the circulation piping 128 or the circulation piping 128 together with the pump 140, heater 142, thermometer 143, and filter 144 provided in the circulation piping 128 is also temporarily referred to as the temperature adjustment system piping.

[0203] In the regeneration tank 20B, the liquid temperature is also maintained using the circulation pipe 128, the pump 140, and the heater 142. The heater 142 contributes to the liquid temperature maintenance process. During the liquid temperature maintenance process, valves 128B and 14B are open, and valves 126B, 164B, 130B, 16B, and 134A are closed.

[0204] When the liquid temperature maintenance process is being performed in the regeneration tank 20B, the regeneration process can also be performed using the regeneration tank 20A. Performing the regeneration process using the regeneration tank 20A while performing the liquid temperature maintenance process using the regeneration tank 20B, or performing the regeneration process using the regeneration tank 20B while performing the liquid temperature maintenance process using the regeneration tank 20A, contributes to improving the efficiency of the regeneration process and the liquid temperature maintenance process.

[0205] The regeneration process using the regeneration tank 20A and the regeneration process using the regeneration tank 20B may be performed in parallel, and the liquid temperature maintenance process using the regeneration tank 20A and the liquid temperature maintenance process using the regeneration tank 20B may be performed in parallel.

[0206] During the regeneration process, organic matter in the waste liquid is also decomposed. For example, the organic matter is the resist formed on the surface of the substrate W and removed by the processing liquid. During electrolysis, the organic matter is decomposed as follows:

[0207] S2O8 2- →2SO4 - ·

[0208] 2SO4 - +2H2O→2HSO4 2- +2OH·

[0209] C, H (organic matter) + 2SO4 - →2HSO4 - +xCO2+yH2O

[0210] 2HSO4 - +xH2O→2H2SO5+xH2

[0211] C, H (organic matter) + 2OH → xCO2 + yH2O

[0212] The decomposition of the organic matter helps reduce foreign matter contained in the third sulfur-acid-containing liquid and helps maintain the functions of the filters 144 , 152 , and 158 .

[0213] <2-5. Supply of First Sulfuric Acid-Containing Liquid>

[0214] The regeneration tank 20A and the regeneration tank 20B can switchably supply the first sulfuric acid-containing liquid to the supply tank 10. For example, valves 14A and 128A are opened to circulate the first sulfuric acid-containing liquid through the circulation pipe 128. Simultaneously, valve 132A is opened to supply the treatment liquid from the regeneration tank 20A to the supply tank 10 via the supply pipe 100. At this time, valves 130A and 134A can also be closed to store the waste liquid from the recovery tanks 30A and 30B in the regeneration tank 20B.

[0215] If the temperature of the first sulfuric acid-containing liquid stored in the regeneration tank 20A has not reached the desired temperature, the valve 128A can be opened while the valves 130A and 132A are closed to continue the liquid temperature maintenance process using the circulation pipe 128. Then, the valve 134A can be opened to supply the first sulfuric acid-containing liquid that has reached the desired temperature and is circulating in the circulation pipe 130 from the regeneration tank 20B to the supply tank 10. This operation facilitates the continuous supply of the first sulfuric acid-containing liquid to the supply tank 10.

[0216] Based on the above, the supply pipe 100 and the supply pipe 132 can be considered as a path for supplying the first sulfuric acid-containing liquid to the supply tank 10, that is, a supply path. Similarly, the supply pipe 100 and the supply pipe 134 can be considered as a path for supplying the first sulfuric acid-containing liquid to the supply tank 10, that is, a supply path. The first sulfuric acid-containing liquid flowing in this supply path corresponds to the regenerated sulfuric acid described above.

[0217] The supply of the first sulfuric acid-containing liquid from the regeneration tank 20A to the supply pipe 100 is regulated by the opening of valve 132A, and the supply of the first sulfuric acid-containing liquid from the regeneration tank 20B to the supply pipe 100 is regulated by the opening of valve 134A. The supply of the first sulfuric acid-containing liquid from the supply pipe 100 to the supply tank 10 is regulated by the opening of valve 100A. The supply of sulfuric acid from the supply pipe 220 to the supply tank 10 is regulated by the opening of valve 12A.

[0218] The openings of valves 12A, 100A, 132A, and 134A are controlled by control unit 90 based on, for example, the storage level of the first sulfuric acid-containing liquid in supply tank 10. When, for example, only the first sulfuric acid-containing liquid supplied from supply pipe 100, which is regenerated sulfuric acid, is stored in supply tank 10 and the predetermined level is insufficient, valve 12A is opened to supply sulfuric acid from supply pipe 220 to supply tank 10.

[0219] <3. Sulfuric acid regeneration treatment>

[0220] As described above, the substrate processing apparatus 1 operates to generate the first sulfuric acid-containing liquid from the waste liquid. The first sulfuric acid-containing liquid is supplied to the supply tank 10 as regenerated sulfuric acid to be used for generating the processing liquid.

[0221] Figure 9 FIG. 1 is a flow chart illustrating the process of regenerating sulfuric acid from waste liquid as the first sulfuric acid-containing liquid. Figure 9 Hereinafter, this process is referred to as "sulfuric acid regeneration process". The sulfuric acid regeneration process includes steps S11, S12, S13, S14, S15, S16, and S17. The sulfuric acid regeneration process may also include step S18.

[0222] At the start of sulfuric acid regeneration, either or both regeneration tanks 20A and 20B are connected to the electrolysis system piping. When regeneration tank 20A is connected to the electrolysis system piping, valves 16A and 130A are open, and valves 14A and 128A are closed. When regeneration tank 20B is connected to the electrolysis system piping, valves 16B and 130B are open, and valves 14B and 128B are closed. Step S11 is executed with either or both regeneration tanks 20A and 20B connected to the electrolysis system piping.

[0223] In step S11, it is determined whether the sulfuric acid concentration in the third sulfuric acid-containing liquid is less than a first predetermined value. As described above, the concentration meter 146 does not distinguish between the concentration of sulfuric acid and the concentration of persulfuric acid. The first predetermined value corresponds to a value that is desired as the upper limit of the water concentration in the third sulfuric acid-containing liquid.

[0224] If the result of the determination in step S11 is negative, it can be estimated that the water concentration in the third sulfuric acid-containing liquid is below the desired upper limit. In this case, steps S12, S13, S14, S15, and S16 are not executed, and step S17 is executed.

[0225] If the result of the determination in step S11 is positive, it can be estimated that the concentration of water in the third sulfuric acid-containing liquid is greater than the value expected as the upper limit. In this case, steps S12, S13, S14, S15, and S16 are executed, and then step S17 is executed.

[0226] Step S12 starts electrolysis. The execution of step S12 is equivalent to the start of the previous process. Through this electrolysis, water is decomposed into oxygen and hydrogen ions, and the sulfuric acid concentration increases.

[0227] The electrolysis started in step S12 is continued while step S13 is executed simultaneously. In step S13, a determination is made as to whether the sulfuric acid concentration is greater than a second predetermined value. The second predetermined value is set to be greater than the first predetermined value. If the determination in step S13 is affirmative, it can be estimated that the water concentration in the third sulfuric acid-containing liquid is below the desired upper limit. At this point, it is assumed that the second sulfuric acid-containing liquid has been generated from the third sulfuric acid-containing liquid, and the electrolysis is stopped in step S14.

[0228] If the result of the determination in step S13 is negative, step S13 is repeatedly executed and electrolysis is continued until the result of the determination becomes positive.

[0229] By stopping the electrolysis in step S14, the previous process ends. After stopping the electrolysis in step S14, step S15 is executed.

[0230] In step S15, the temperature of the second sulfuric acid-containing liquid stored in the regeneration tanks 20A and 20B (abbreviated as "liquid temperature" in the figure) is adjusted to the deactivation temperature. Execution of step S15 corresponds to a post-process.

[0231] The degree of peroxydisulfuric acid deactivation can be estimated by the time the second sulfuric acid-containing liquid is maintained at the deactivation temperature. The post-process ends when its operating time exceeds a predetermined time. In step S16, a determination is made as to whether a predetermined time has elapsed since the second sulfuric acid-containing liquid was adjusted to the deactivation temperature. In step S16, a determination is made as to whether a predetermined time has elapsed since step S15 was executed.

[0232] If the result of the determination in step S16 is negative, step S16 is repeatedly executed, and the liquid temperature is continuously adjusted to the deactivation temperature until the result of the determination becomes positive.

[0233] If the determination result in step S16 is positive, it is considered that the peroxydisulfuric acid has been deactivated to a concentration lower than the desired value. This deactivation generates the first sulfuric acid-containing liquid from the second sulfuric acid-containing liquid. If the determination result in step S16 is positive, the subsequent process ends.

[0234] If the determination result in step S16 is affirmative, step S17 is executed to switch the piping from the electrolysis system to the temperature control system. For regeneration tank 20A, this switch is achieved by closing valves 16A and 130A and opening valves 14A and 128A. For regeneration tank 20B, this switch is achieved by closing valves 16B and 130B and opening valves 14B and 128B. Step S17 is executed, and the sulfuric acid regeneration process is completed.

[0235] It is also possible to further include step S18 in the sulfuric acid regeneration process. After executing step S17, step S18 adjusts the temperature of the first sulfuric acid-containing liquid generated in steps S15 and S16 (abbreviated as "liquid temperature" in the figure) to a treatment temperature. The "treatment temperature" referred to here is a temperature suitable for storage in the supply tank 10. Step S18 corresponds to a liquid temperature maintenance process.

[0236] <4. Transformation>

[0237] In the above embodiment, for example, an in-pipe heater may be provided in the supply pipe 100 in the supply recovery section 3 , and the heater 156 in the regeneration section 7 may be omitted.

[0238] Sometimes, the concentration meter 146 can also distinguish between the concentration of peroxydisulfuric acid, the concentration of sulfuric acid, and the concentration of peroxymonosulfuric acid (e.g., by spectroscopic analysis). The determination in step S16 determines the degree of inactivation of the peroxydisulfuric acid. In this case, the determination condition in step S16 can be changed to "whether the concentration of peroxydisulfuric acid has not reached a predetermined concentration."

[0239] Furthermore, it goes without saying that all or part of the components constituting each of the above-described embodiments and various modifications can be appropriately combined within a range that does not conflict with each other.

[0240] Description of reference numerals:

[0241] 1: Substrate processing equipment

[0242] 10: Supply tank

[0243] 20A, 20B: Regeneration tank

[0244] 21: Electrolysis unit

[0245] 100: Supply piping

[0246] 106B: Nozzle

[0247] 146: Concentration meter

[0248] 150, 156: Heater

[0249] 128, 130: Circulation piping

[0250] W: substrate

Claims

1. A substrate processing apparatus for processing a substrate using a processing liquid containing sulfuric acid and an aqueous hydrogen peroxide solution, wherein: have: a nozzle for supplying a first sulfuric acid-containing liquid and a hydrogen peroxide aqueous solution as the processing liquid to the substrate; a first tank storing the first sulfuric acid-containing liquid supplied to the nozzle; an electrolysis path for electrolyzing the treatment liquid, i.e., the waste liquid, after the substrate has been treated, to generate a second sulfuric acid-containing liquid; a concentration reducing device for reducing the concentration of peroxodisulfuric acid in the second sulfuric acid-containing liquid to generate the first sulfuric acid-containing liquid; as well as A supply path is a path for supplying the first sulfur-containing liquid to the first tank.

2. The substrate processing apparatus according to claim 1, wherein: The concentration reducing device includes a first heater.

3. The substrate processing apparatus according to claim 1 or 2, wherein: The electrolysis path has: an electrolysis device for said electrolysis; and The concentration meter measures the concentrations of sulfuric acid, peroxymonosulfuric acid, and peroxydisulfuric acid, which are the liquids flowing through the electrolysis device.

4. The substrate processing apparatus according to any one of claims 1 to 3, wherein: The second tank is further provided with the waste liquid and stores the third sulfuric acid-containing liquid. The third sulfur-containing liquid includes at least any one of the waste liquid, the first sulfur-containing liquid, and the second sulfur-containing liquid. The third sulfur-containing liquid circulates among the second tank, the electrolysis path, and the concentration reducing device.

5. The substrate processing apparatus according to any one of claims 1 to 4, wherein: The supply path includes a second heater.

6. The substrate processing apparatus according to any one of claims 1 to 5, wherein: The nozzle mixes the first sulfuric acid-containing liquid with an aqueous hydrogen peroxide solution and supplies the treatment liquid to the substrate.

7. A substrate processing method, comprising processing a substrate using a processing solution comprising sulfuric acid and an aqueous hydrogen peroxide solution, wherein: The substrate processing method comprises: supplying a first sulfuric acid-containing liquid and a hydrogen peroxide aqueous solution as the processing liquid to the substrate; a step of electrolyzing the treatment liquid, i.e., the waste liquid, after the substrate has been treated to generate a second sulfuric acid-containing liquid; and a step of reducing the concentration of peroxodisulfuric acid in the second sulfuric acid-containing liquid to generate the first sulfuric acid-containing liquid.

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