Substrate processing apparatus and substrate processing method

Abstract

The substrate processing apparatus of the present invention uses a processing liquid to process a substrate. The substrate processing apparatus includes: a processing liquid storage unit, an inflow pipe, at least one circulation pipe, a pump, a filter unit, a pressure regulating valve, and a control unit. The processing liquid storage unit stores the processing liquid. The processing liquid flows from the processing liquid storage unit into the inflow pipe. The upstream end of the at least one circulation pipe is connected to the inflow pipe, and the downstream end is connected to the processing liquid storage unit, thereby circulating the processing liquid. The pump is disposed in the inflow pipe. The pump is driven by gas pressure, allowing the processing liquid to flow. The filter unit is disposed in the inflow pipe. The filter unit removes foreign matter from the processing liquid. The pressure regulating valve adjusts the pressure of the gas supplied to the pump, and adjusts the ejection pressure, which represents the pressure at which the pump ejects the processing liquid. The control unit controls the pressure regulating valve to perform a pressure boosting process when the pump starts operating. The aforementioned pressurization process includes the following steps: gradually increasing the pressure of the gas supplied to the aforementioned pump, and gradually increasing the aforementioned ejection pressure to the target pressure.

Description

Substrate Processing Apparatus and Substrate Processing Method The present invention relates to a substrate processing apparatus and a substrate processing method. There is known a substrate processing apparatus having a circulation pipeline (for example, refer to Patent Document 1). A pump and a filter are provided in the circulation pipeline. The pump transports the processing liquid in such a manner that the processing liquid circulates in the circulation pipeline. The filter removes foreign matters from the processing liquid circulating in the circulation pipeline. The substrate processing apparatus sometimes stops operating when performing operations such as replacement of the processing liquid or resetting from a failure. When the operation of the substrate processing apparatus stops, the circulation of the processing liquid in the circulation pipeline also stops. When the operation of the substrate processing apparatus is started again after the operation such as replacement of the processing liquid or resetting from a failure is completed, the circulation of the processing liquid via the circulation pipeline also starts again. However, when the circulation of the processing liquid is started again, due to the ejection pressure of the pump, the foreign matters captured by the filter are released from the filter, and the number of foreign matters adhering to the substrate sometimes increases. This problem is caused by a large pressure corresponding to the ejection pressure of the pump being applied to the filter all at once. Regarding this problem, Patent Document 1 describes a technique for controlling a back pressure valve and a pump provided in a circulation pipeline to suppress the release of foreign matters from the filter when the circulation of the processing liquid is started again. Specifically, first, the control unit controls the back pressure valve to maintain the valve opening degree of the back pressure valve at the maximum valve opening degree. After that, the control unit adjusts the regulator so that the ejection pressure of the pump becomes a first pressure, and drives the pump. As a result, the circulation of the processing liquid is started again. After that, the control unit controls the back pressure valve to control the pressure on the upstream side of the filter to a specified constant value. After the control unit controls the pressure on the upstream side of the filter to the specified constant value, the control unit controls the back pressure valve so that the valve opening degree of the back pressure valve becomes smaller. After that, corresponding to the elapse of a specified time since the start of driving of the pump, the control unit adjusts the regulator so that the ejection pressure of the pump becomes a second pressure. Here, the second pressure indicates the maximum ejection pressure of the pump, and the first pressure indicates a pressure lower than the second pressure (the maximum ejection pressure of the pump). Also, the specified time since the start of driving of the pump is adjusted to the time required until the pressure difference between the upstream side and the downstream side of the filter becomes stable. According to the technique described in Patent Document 1, when the circulation of the processing liquid is started again, it is suppressed that the pressure difference between the upstream side and the downstream side of the filter is larger than the pressure resistance of the filter. As a result, it is suppressed that foreign matters pass through the filter and contaminate the circulation pipeline. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-41039 [Problems to be Solved by the Invention] The inventors of the present invention application have conducted in-depth research on a technique for suppressing an increase in foreign matter adhering to a substrate when the circulation of the processing liquid starts again by means different from those described in Patent Document 1. An object of the present invention is to provide a substrate processing apparatus and a substrate processing method capable of suppressing an increase in foreign matter adhering to a substrate when the circulation of the processing liquid starts again. [Technical means for solving the problem] According to one aspect of the present invention, a substrate processing apparatus is an apparatus that processes a substrate using a processing liquid. The substrate processing apparatus includes: a processing liquid storage unit, an inflow pipe, at least one circulation pipe, a pump, a filtration unit, a pressure regulating valve, and a control unit. The processing liquid storage unit stores the processing liquid. The processing liquid flows into the inflow pipe from the processing liquid storage unit. The upstream end of the at least one circulation pipe is connected to the inflow pipe, and the downstream end is connected to the processing liquid storage unit to circulate the processing liquid. The pump is disposed in the inflow pipe. The pump is driven by the pressure of a gas to circulate the processing liquid. The filtration unit is disposed in the inflow pipe. The filtration unit removes foreign matter from the processing liquid. The pressure regulating valve adjusts the pressure of the gas supplied to the pump and adjusts the ejection pressure indicating the pressure at which the pump ejects the processing liquid. The control unit controls the pressure regulating valve at the start of driving of the pump and performs a pressure increasing process. The pressure increasing process includes the following process: gradually increasing the pressure of the gas supplied to the pump and gradually increasing the ejection pressure to a target pressure. In one embodiment, the above-described substrate processing apparatus further includes a memory unit. The memory unit stores history information indicating information related to the usage history of the filtration unit. The control unit adjusts the period during which the ejection pressure is gradually increased by the pressure increasing process based on the history information. In one embodiment, the control unit adjusts the period during which the ejection pressure is gradually increased by the pressure increasing process by adjusting the pressure of the gas supplied to the pump at the start of the pressure increasing process based on the history information. In one embodiment, the at least one circulation pipe includes: a first circulation pipe and a second circulation pipe shorter than the first circulation pipe. The above-described substrate processing apparatus further includes a circulation control mechanism. The circulation control mechanism controls the circulation of the processing liquid through the first circulation pipe and the circulation of the processing liquid through the second circulation pipe. The control unit controls the circulation control mechanism at the start of driving of the pump to start the circulation of the processing liquid through the second circulation pipe. The control unit controls the circulation control mechanism during the process of gradually increasing the ejection pressure by the pressure increasing process to start the circulation of the processing liquid through the first circulation pipe and stop the circulation of the processing liquid through the second circulation pipe. In one embodiment, the pump described above has: a first gas chamber, a second gas chamber, a first liquid chamber, and a second liquid chamber. The gas described above flows into the first gas chamber and the second gas chamber. The processing liquid flows into the first liquid chamber and the second liquid chamber. The volumes of the first gas chamber and the second gas chamber are respectively variable. The volumes of the first liquid chamber and the second liquid chamber are respectively variable. By the gas flowing into the first gas chamber, the processing liquid is sent from the first liquid chamber toward the inflow pipe. By the gas flowing into the second gas chamber, the processing liquid is sent from the second liquid chamber toward the inflow pipe. According to another aspect of the present invention, a substrate processing apparatus is an apparatus that processes a substrate using a processing liquid. The substrate processing apparatus includes: a processing liquid storage unit, an inflow pipe, at least one circulation pipe, a circulation control mechanism, a pump, a filter unit, a drain pipe, a drain valve, and a control unit. The processing liquid storage unit stores the processing liquid. The processing liquid flows from the processing liquid storage unit toward the inflow pipe. The upstream end of the at least one circulation pipe is connected to the inflow pipe, and the downstream end is connected to the processing liquid storage unit to circulate the processing liquid. The circulation control mechanism controls the circulation of the processing liquid through the at least one circulation pipe. The pump is disposed in the inflow pipe. The pump causes the processing liquid to flow. The filter unit is disposed in the inflow pipe. The filter unit removes foreign matter from the processing liquid. The drain pipe discharges the processing liquid. The drain valve is disposed in the drain pipe. The drain valve controls the flow of the processing liquid in the drain pipe. The control unit controls the circulation control mechanism, the ejection pressure indicating the pressure at which the pump ejects the processing liquid, and the drain valve, and performs a drain process, a circulation start process, and a pressure increase process. The filter unit has a filter membrane. The filter membrane captures the foreign matter contained in the processing liquid. The drain pipe discharges the processing liquid that has passed through the filter membrane. The drain process includes the following process: at the start of driving of the pump, the ejection pressure is increased to a first pressure, and the drain valve is controlled to discharge the processing liquid from the drain pipe. The control unit reduces the ejection pressure to a second pressure lower than the first pressure in response to discharging the processing liquid from the drain pipe. The control unit performs the circulation start process and the pressure increase process in response to reducing the ejection pressure from the first pressure to the second pressure. The circulation start process includes the following process: the circulation control mechanism and the drain valve are controlled to stop the discharge of the processing liquid from the drain pipe and start the circulation of the processing liquid through one of the at least one circulation pipes. The pressure increase process includes the following process: the ejection pressure is gradually increased in stages to a third pressure greater than the second pressure, or the ejection pressure is gradually increased to a third pressure greater than the second pressure. In one embodiment, the drain pipe is connected to the filtration unit or the inflow pipe. In one embodiment, the drain pipe is connected to the inflow pipe on the upstream side of the connection portion of each of the at least one circulation pipe and the inflow pipe. In one embodiment, the substrate processing apparatus further includes a memory unit. The memory unit stores history information indicating information related to the usage history of the filtration unit. The control unit adjusts the period during which the ejection pressure is increased stepwise or gradually by the pressure increase process based on the history information. In one embodiment, the control unit adjusts the pressure of the gas supplied to the pump at the start of the pressure increase process based on the history information, thereby adjusting the period during which the ejection pressure is gradually increased by the pressure increase process. In one embodiment, the at least one circulation pipe includes a first circulation pipe and a second circulation pipe shorter than the first circulation pipe. The circulation control mechanism controls the circulation of the processing liquid through the first circulation pipe and the circulation of the processing liquid through the second circulation pipe. The circulation start process includes the following process: controlling the circulation control mechanism to start the circulation of the processing liquid through the second circulation pipe. The control unit controls the circulation control mechanism during the process of gradually or stepwise increasing the ejection pressure by the pressure increase process to start the circulation of the processing liquid through the first circulation pipe and stop the circulation of the processing liquid through the second circulation pipe. In one embodiment, the pump is driven by the pressure of a gas. In one embodiment, the pump has a first gas chamber, a second gas chamber, a first liquid chamber, and a second liquid chamber. The gas flows into the first gas chamber and the second gas chamber. The processing liquid flows into the first liquid chamber and the second liquid chamber. The volumes of the first gas chamber and the second gas chamber are variable respectively. The volumes of the first liquid chamber and the second liquid chamber are variable respectively. By the gas flowing into the first gas chamber, the processing liquid is sent from the first liquid chamber to the inflow pipe. By the gas flowing into the second gas chamber, the processing liquid is sent from the second liquid chamber to the inflow pipe. In one embodiment, the first pressure is greater than the third pressure. In one embodiment, the second pressure includes the pressure in a state where the driving of the pump is stopped. According to another aspect of the present invention, a substrate processing method is a method for processing a substrate by a substrate processing apparatus. The aforementioned substrate processing apparatus includes a processing liquid storage unit, an inflow pipe, at least one circulation pipe, a pump, and a filtration unit. The aforementioned processing liquid storage unit stores a processing liquid used for processing the aforementioned substrate. The aforementioned processing liquid flows into the aforementioned inflow pipe from the aforementioned processing liquid storage unit. The upstream end of the aforementioned at least one circulation pipe is connected to the aforementioned inflow pipe, and the downstream end is connected to the aforementioned processing liquid storage unit to circulate the aforementioned processing liquid. The aforementioned pump is disposed in the aforementioned inflow pipe. The aforementioned pump is driven by the pressure of a gas to cause the aforementioned processing liquid to flow. The aforementioned filtration unit is disposed in the aforementioned inflow pipe. The aforementioned filtration unit removes foreign substances from the aforementioned processing liquid. The substrate processing method includes a circulation start step of starting the drive of the aforementioned pump and starting the circulation of the aforementioned processing liquid. The aforementioned circulation start step includes a step of performing a pressure increase process when starting the drive of the aforementioned pump. The aforementioned pressure increase process includes the following process: gradually increasing the pressure of the aforementioned gas supplied to the aforementioned pump, and gradually increasing the ejection pressure indicating the pressure at which the aforementioned pump ejects the aforementioned processing liquid. In one embodiment, the above substrate processing method further includes the following step: based on the history information indicating information related to the usage history of the above filtration unit, adjusting the period during which the ejection pressure is gradually increased by the above pressure increase process. In one embodiment, the above substrate processing method further includes the following step: based on the history information indicating information related to the usage history of the above filtration unit, adjusting the pressure of the above gas supplied to the above pump at the start of the above pressure increase process, whereby the period during which the ejection pressure is gradually increased by the above pressure increase process is adjusted. In one embodiment, the aforementioned at least one circulation pipe includes: a first circulation pipe, and a second circulation pipe shorter than the aforementioned first circulation pipe. The aforementioned circulation start step includes the following steps: when starting the drive of the aforementioned pump, starting the circulation of the aforementioned processing liquid passing through the aforementioned second circulation pipe; during the process of gradually increasing the ejection pressure by the aforementioned pressure increase process, starting the circulation of the aforementioned processing liquid passing through the aforementioned first circulation pipe and stopping the circulation of the aforementioned processing liquid passing through the aforementioned second circulation pipe. According to another aspect of the present invention, a substrate processing method is a method for processing a substrate by a substrate processing apparatus. The aforementioned substrate processing apparatus includes: a processing liquid storage unit, an inflow pipe, at least one circulation pipe, a pump, a filtration unit, and a drainage pipe. The aforementioned processing liquid storage unit stores a processing liquid used for processing the aforementioned substrate. The processing liquid flows into the aforementioned inflow pipe from the aforementioned processing liquid storage unit. The upstream end of the aforementioned at least one circulation pipe is connected to the aforementioned inflow pipe, and the downstream end is connected to the aforementioned processing liquid storage unit to circulate the aforementioned processing liquid. The aforementioned pump is disposed in the aforementioned inflow pipe. The aforementioned pump causes the aforementioned processing liquid to flow. The aforementioned filtration unit is disposed in the aforementioned inflow pipe. The aforementioned filtration unit removes foreign matters from the aforementioned processing liquid. The aforementioned drainage pipe discharges the aforementioned processing liquid. The aforementioned filtration unit has a filtration membrane. The aforementioned filtration membrane captures the aforementioned foreign matters contained in the aforementioned processing liquid. The aforementioned drainage pipe discharges the aforementioned processing liquid that has passed through the aforementioned filtration membrane. This substrate processing method includes the following steps: at the start of driving of the aforementioned pump, increasing the ejection pressure indicating the pressure at which the aforementioned pump ejects the aforementioned processing liquid to a first pressure, and discharging the aforementioned processing liquid from the aforementioned drainage pipe; corresponding to discharging the aforementioned processing liquid from the aforementioned drainage pipe, reducing the aforementioned ejection pressure to a second pressure lower than the aforementioned first pressure; and corresponding to reducing the aforementioned ejection pressure from the aforementioned first pressure to the aforementioned second pressure, performing a circulation start process and a pressure increase process. The aforementioned circulation start process includes the following process: starting the circulation of the aforementioned processing liquid through one of the aforementioned at least one circulation pipes, and stopping the discharge of the aforementioned processing liquid from the aforementioned drainage pipe. The aforementioned pressure increase process includes the following process: increasing the aforementioned ejection pressure stepwise to a third pressure greater than the aforementioned second pressure, or gradually increasing the aforementioned ejection pressure to a third pressure greater than the aforementioned second pressure. In one embodiment, the above-described substrate processing method further includes a step of adjusting the period during which the ejection pressure is increased stepwise or gradually by the above-described pressure increase process based on history information indicating information related to the usage history of the above-described filtration unit. In one embodiment, the above-described substrate processing method further includes the following step: adjusting the pressure of the gas supplied to the above-described pump at the start of the above-described pressure increase process based on history information indicating information related to the usage history of the above-described filtration unit, whereby the period during which the ejection pressure is gradually increased by the above-described pressure increase process is adjusted. In one embodiment, the aforementioned at least one circulation pipe includes: a first circulation pipe, and a second circulation pipe shorter than the aforementioned first circulation pipe. The aforementioned circulation start process includes the following process: starting the circulation of the aforementioned processing liquid through the aforementioned second circulation pipe. The above-described substrate processing method further includes the following step: during the process of increasing the aforementioned ejection pressure stepwise or gradually by the above-described pressure increase process, starting the circulation of the aforementioned processing liquid through the aforementioned first circulation pipe, and stopping the circulation of the aforementioned processing liquid through the aforementioned second circulation pipe. In one embodiment, the first pressure is greater than the third pressure. In one embodiment, the step of reducing the ejection pressure to the second pressure lower than the first pressure includes the step of stopping the driving of the pump. Hereinafter, with reference to the drawings (FIGS. 1 to 15), embodiments of the substrate processing apparatus and the substrate processing method of the present invention will be described. However, the present invention is not limited to the following embodiments and can be implemented in various aspects without departing from the gist thereof. In addition, for parts where the description is repeated, the description may be appropriately omitted. Also, in the drawings, the same or corresponding parts are denoted by the same reference numerals and will not be described repeatedly. In the substrate processing apparatus and the substrate processing method of the present invention, the "substrate" to be subjected to substrate processing can be applied to various substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical discs, substrates for magnetic discs, and substrates for magneto-optical discs. Hereinafter, embodiments of the present invention will be mainly described by taking the case where a disk-shaped semiconductor wafer is the object of substrate processing as an example, but the substrate processing apparatus and the substrate processing method of the present invention can also be similarly applied to various substrates other than the above-mentioned semiconductor wafers. Also, the shape of the substrate is not limited to a disk shape, and the substrate processing apparatus and the substrate processing method of the present invention can be applied to substrates of various shapes. [Embodiment 1] First, with reference to FIGS. 1 to 5, FIGS. 6A to 6D, and FIGS. 7A to 7C, Embodiment 1 of the present invention will be described. FIG. 1 is a schematic top view of a substrate processing apparatus 100 according to this embodiment. The substrate processing apparatus 100 processes a substrate W using a processing liquid. More specifically, the substrate processing apparatus 100 is a single-wafer type apparatus that processes the substrate W one by one. Hereinafter, the processing of the substrate W by the processing liquid may be referred to as "substrate processing". In addition, the substrate processing apparatus 100 is not particularly limited as long as it is an apparatus for processing the substrate W. For example, the substrate processing apparatus 100 may be a cleaning apparatus, an etching apparatus, a coating apparatus, a developing apparatus, or a film forming apparatus. As shown in FIG. 1, the substrate processing apparatus 100 includes: a plurality of substrate processing units 2, a fluid housing 101, a plurality of fluid tanks 102, a plurality of loading ports LP, an indexer robot IR, a center robot CR, and a control device 110. Each of the loading ports LP accommodates a plurality of stacked substrates W. The indexer robot IR transports the substrate W between the loading port LP and the central robot CR. The central robot CR transports the substrate W between the indexer robot IR and the substrate processing unit 2. In addition, a placement table (path) for temporarily placing the substrate W can be provided between the indexer robot IR and the central robot CR, and the device configuration is such that the substrate W is indirectly transferred between the indexer robot IR and the central robot CR via the placement table. A plurality of substrate processing units 2 form a plurality of towers TW (4 towers TW in FIG. 1). The plurality of towers TW are arranged in a plan view so as to surround the central robot CR. Each tower TW is composed of a plurality of substrate processing units 2 (3 substrate processing units 2 in FIG. 1) stacked vertically. The fluid housing 101 houses the processing liquid. The fluid tank 102 corresponds to one of the plurality of towers TW. The processing liquid in the fluid housing 101 is supplied to all the substrate processing units 2 included in the tower TW corresponding to the fluid tank 102 via any one of the fluid tanks 102. Each of the substrate processing units 2 supplies the processing liquid to the upper surface of the substrate W. As a result, the substrate W is processed by the processing liquid. The processing liquid is not particularly limited as long as it is a liquid that contacts the substrate W. The processing liquid includes, for example, a chemical solution. The chemical solution includes, for example: dilute hydrofluoric acid (DHF), hydrofluoric acid (HF), fluoronitric acid (a mixed solution of hydrofluoric acid and nitric acid (HNO 3 ), buffered hydrofluoric acid (BHF), ammonium fluoride, HFEG (a mixed solution of hydrofluoric acid and ethylene glycol), phosphoric acid (H 3 PO 4 ), sulfuric acid, acetic acid, nitric acid, hydrochloric acid, ammonia water, hydrogen peroxide water, organic acids (e.g., citric acid, oxalic acid), organic bases (e.g., TMAH: tetramethylammonium hydroxide, etc.), sulfuric acid / hydrogen peroxide water mixed solution (SPM), ammonia / hydrogen peroxide water mixed solution (SC1), hydrochloric acid / hydrogen peroxide water (SC2), isopropyl alcohol (IPA), surfactant, or preservative. Alternatively, the liquid chemical may be an organic solvent such as IPA. Specifically, the organic solvent contains: alcohols such as IPA; ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether (PGME) and propylene glycol monoethyl ether (PGEE); propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monoethyl ether acetate; lactate esters such as methyl lactate and ethyl lactate (EL); aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone, 2-heptanone, and cyclohexanone; amides such as N,N-dimethylacetamide and N-methylpyrrolidone; and lactones such as γ-butyrolactone. These organic solvents may be used alone or in combination of two or more. The control device 110 controls the operations of the respective parts of the substrate processing device 100. For example, the control device 110 controls the fluid housing 101, the fluid tank 102, the load port LP, the indexer robot IR, the center robot CR, and the substrate processing unit 2. The control device 110 includes a control unit 111 and a memory unit 112. Based on various information stored in the memory unit 112, the control unit 111 controls the operations of the respective parts of the substrate processing device 100. The control unit 111 has, for example, a processor. As the processor, the control unit 111 may have a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Alternatively, the control unit 111 may have a general-purpose computer or a dedicated calculator. The memory unit 112 stores various information for controlling the operations of the substrate processing device 100. For example, the memory unit 112 stores data and computer programs. The computer program includes a sequence of steps of a computer program that defines the processing when restarting the operations of the substrate processing device 100 after the operations of the substrate processing device 100 are stopped. The data includes various condition data. The conditions include, for example, process conditions. The process conditions define the sequence of substrate processing. The memory unit 112 has a main memory device. As the main memory device, the memory unit 112 may have, for example, a semiconductor memory. The memory unit 112 may further have an auxiliary memory device. As the auxiliary memory device, the memory unit 112 may have at least one of, for example, a semiconductor memory and a hard disk drive. The memory unit 112 may include a removable medium. Next, with reference to FIGS. 1 and 2, the substrate processing device 100 of the present embodiment will be described. FIG. 2 is a diagram showing the configuration of the substrate processing unit 2, the fluid housing 101, and the fluid tank 102 included in the substrate processing device 100 of the present embodiment. As shown in FIG. 2, the substrate processing unit 2 includes a chamber 4, a spin chuck 6, and a spray nozzle 8, respectively. The chamber 4 houses the spin chuck 6 and the spray nozzle 8. The spin chuck 6 holds the substrate W. Specifically, the substrate W is held by the spin chuck 6 in a horizontal posture. Further, the spin chuck 6 rotates the held substrate W. Specifically, the spin chuck 6 rotates the substrate W with the center of the substrate W as the rotation center. The spray nozzle 8 supplies the processing liquid to the substrate W. Specifically, the spray nozzle 8 sprays the processing liquid toward the rotating substrate W. The spray nozzle 8 can spray the processing liquid from a position facing the center of the substrate W to the substrate W, or can spray the processing liquid to the substrate W while moving above the substrate W. As shown in FIG. 2, for each substrate processing unit 2, the substrate processing apparatus 100 includes an individual supply pipe 17 and an individual valve 31. The individual valve 31 is housed in the fluid tank 102. The downstream end of each of the individual supply pipes 17 is connected to the corresponding spray nozzle 8. The individual supply pipe 17 is a tubular member through which the processing liquid flows, and allows the processing liquid to flow to the corresponding spray nozzle 8. The individual valve 31 is provided in the individual supply pipe 17 to control the start and stop of the supply of the processing liquid to the spray nozzle 8. Specifically, the individual valve 31 is an on-off valve that can be opened and closed. The supply of the processing liquid starts when the individual valve 31 is opened. The supply of the processing liquid stops when the individual valve 31 is closed. The opening and closing operation of the individual valve 31 is controlled by the control device 110 (control unit 111). The substrate processing apparatus 100 further includes a processing liquid tank 11, an inflow pipe 13, and a plurality of outer circulation pipes 15. The processing liquid tank 11 and the inflow pipe 13 are housed in the fluid housing 101. The processing liquid tank 11 stores the processing liquid. The processing liquid tank 11 is an example of a "processing liquid storage unit". The outer circulation pipes 15 correspond to one of the plurality of towers TW, respectively. In other words, the outer circulation pipes 15 correspond to one of the plurality of fluid tanks 102, respectively. Toward the inflow pipe 13, the processing liquid flows from the processing liquid tank 11. The inflow pipe 13 is a tubular member through which the processing liquid flows. Specifically, the upstream end of the inflow pipe 13 is connected to the processing liquid tank 11, and the processing liquid flows into the inflow pipe 13 from the upstream end of the inflow pipe 13. The external circulation pipes 15 are tubular members for the flow of the processing liquid. The upstream ends of the external circulation pipes 15 are connected to the inflow pipe 13. In the present embodiment, the upstream ends of the external circulation pipes 15 are connected to the downstream end of the inflow pipe 13. The downstream ends of the external circulation pipes 15 are connected to the processing liquid tank 11. The external circulation pipes 15 circulate the processing liquid respectively. Specifically, towards the upstream ends of the external circulation pipes 15, the processing liquid flows in from the inflow pipe 13, and the processing liquid flows through each external circulation pipe 15. As a result, the processing liquid flows out from the downstream ends of the external circulation pipes 15, and the processing liquid returns to the processing liquid tank 11. The external circulation pipes 15 are an example of the "circulation pipes" and the "first circulation pipes". In each fluid tank 102, the upstream ends of the corresponding plurality of individual supply pipes 17 are connected to the corresponding external circulation pipes 15. When the individual valve 31 is opened, a part of the processing liquid flowing through the external circulation pipe 15 flows into the corresponding individual supply pipe 17. As a result, the processing liquid is supplied from the individual supply pipe 17 to the ejection nozzle 8, and the processing liquid is ejected from the ejection nozzle 8 to the substrate W. As shown in FIG. 2, the substrate processing apparatus 100 further includes: an internal circulation pipe 19, a circulation pump 21, a pulsation damper 23, a thermostat 25, a filter section 27, and a circulation control mechanism 28. The upstream end of the internal circulation pipe 19 is connected to the inflow pipe 13. More specifically, the upstream end of the internal circulation pipe 19 is connected to the inflow pipe 13 at a position upstream of the connection portion P1 between the inflow pipe 13 and each external circulation pipe 15. Therefore, the connection portion P1 between the inflow pipe 13 and each external circulation pipe 15 is located downstream of the connection portion P2 between the inflow pipe 13 and the internal circulation pipe 19. Hereinafter, the connection portion P1 between the inflow pipe 13 and each external circulation pipe 15 may be referred to as the "first connection portion P1". Similarly, the connection portion P2 between the inflow pipe 13 and the internal circulation pipe 19 may be referred to as the "second connection portion P2". The internal circulation pipe 19 is a tubular member for the flow of the processing liquid. The downstream end of the internal circulation pipe 19 is connected to the processing liquid tank 11. The internal circulation pipe 19 circulates the processing liquid. Specifically, the processing liquid flows into the upstream end of the internal circulation pipe 19 from the inflow pipe 13, and the processing liquid flows through the internal circulation pipe 19. As a result, the processing liquid flows out from the downstream end of the internal circulation pipe 19, and the processing liquid returns to the processing liquid tank 11. The internal circulation pipe 19 is an example of the "second circulation pipe". The pipe length of the internal circulation pipe 19 is shorter than that of each external circulation pipe 15. The internal circulation pipe 19 is housed in the fluid housing 101. The internal circulation pipe 19 circulates the processing liquid in the fluid housing 101. The circulation pump 21 is disposed in the inflow pipe 13. The circulation pump 21 circulates the processing liquid. Specifically, by driving the circulation pump 21, the processing liquid is transported from the circulation pump 21. As a result, the processing liquid circulates. In the present embodiment, the circulation pump 21 is driven by the pressure of a gas. The circulation pump 21 is controlled by the control device 110 (control unit 111). The pulsation damper 23 is disposed in the inflow pipe 13. Specifically, the pulsation damper 23 is disposed on the downstream side of the circulation pump 21. The pulsation damper 23 suppresses the pulsation of the processing liquid sent out from the circulation pump 21. The thermostat 25 is disposed in the inflow pipe 13. Specifically, the thermostat 25 is disposed on the downstream side of the circulation pump 21. In the present embodiment, the thermostat 25 is disposed on the downstream side of the pulsation damper 23. The thermostat 25 heats the processing liquid flowing in the inflow pipe 13. Accordingly, the outer circulation pipes 15 respectively circulate the processing liquid heated by the thermostat 25. Similarly, the inner circulation pipe 19 circulates the processing liquid heated by the thermostat 25. The thermostat 25 includes, for example, a heater. The filter unit 27 is disposed in the inflow pipe 13 to remove foreign matters from the processing liquid flowing in the inflow pipe 13. Specifically, the filter unit 27 is disposed on the downstream side of the circulation pump 21 to remove foreign matters from the processing liquid sent out from the circulation pump 21. In the present embodiment, the filter unit 27 is disposed between the thermostat 25 and the first connection portion P1. In detail, the filter unit 27 is disposed on the upstream side of the second connection portion P2. As a result, the clean processing liquid from which foreign matters have been removed flows into the inner circulation pipe 19 and the respective outer circulation pipes 15. The circulation control mechanism 28 controls the circulation of the processing liquid via each of the outer circulation pipes 15 and the circulation of the processing liquid via the inner circulation pipe 19. Specifically, the circulation control mechanism 28 controls the start and stop of the circulation of the processing liquid via each of the outer circulation pipes 15. Also, the circulation control mechanism 28 controls the start and stop of the circulation of the processing liquid via the inner circulation pipe 19. The circulation control mechanism 28 is controlled by the control device 110 (control unit 111). In the present embodiment, the circulation control mechanism 28 includes a plurality of outer circulation valves 29 and an inner circulation valve 33. The outer circulation valves 29 respectively correspond to one of the plurality of outer circulation pipes 15. The outer circulation valves 29 are respectively disposed in the corresponding outer circulation pipes 15. The outer circulation valves 29 respectively control the start and stop of the flow of the processing liquid in the corresponding outer circulation pipes 15. The outer circulation valve 29 is an example of a "circulation valve" and a "first circulation valve". In detail, the outer circulation valve 29 is an on-off valve that can be opened and closed. When the outer circulation valve 29 is opened, the processing liquid flows in the corresponding outer circulation pipe 15. When the outer circulation valve 29 is closed, the flow of the processing liquid in the corresponding outer circulation pipe 15 stops. The opening and closing operations of the outer circulation valves 29 are controlled by the control device 110 (control unit 111). The plurality of outer circulation valves 29 are housed in the fluid housing 101. The internal circulation valve 33 is provided in the internal circulation pipe 19. The internal circulation valve 33 controls the start and stop of the flow of the processing liquid in the internal circulation pipe 19. The internal circulation valve 33 is an example of a "second circulation valve". Specifically, the internal circulation valve 33 is an on-off valve that can be opened and closed. When the internal circulation valve 33 is opened, the processing liquid flows in the internal circulation pipe 19. When the internal circulation valve 33 is closed, the flow of the processing liquid in the internal circulation pipe 19 stops. The opening and closing operation of the internal circulation valve 33 is controlled by the control device 110 (control unit 111). The internal circulation valve 33 is housed in the fluid housing 101. When the control device 110 (control unit 111) circulates the processing liquid through the plurality of external circulation pipes 15, the plurality of external circulation valves 29 are set to the open state. Also, when the control device 110 (control unit 111) circulates the processing liquid through the internal circulation pipe 19, the internal circulation valve 33 is set to the open state. Specifically, when the control device 110 (control unit 111) circulates the processing liquid through the plurality of external circulation pipes 15, the plurality of external circulation valves 29 are set to the open state, and the internal circulation valve 33 is set to the closed state. When the control device 110 (control unit 111) circulates the processing liquid through the internal circulation pipe 19, the plurality of external circulation valves 29 are set to the closed state, and the internal circulation valve 33 is set to the open state. Next, with reference to FIGS. 1 to 3, the substrate processing apparatus 100 of the present embodiment will be described. FIG. 3 is a diagram showing the configuration of the fluid housing 101 included in the substrate processing apparatus 100 of the present embodiment. As shown in FIG. 3, the substrate processing apparatus 100 further includes a pump drive mechanism 5. The pump drive mechanism 5 is housed in the fluid housing 101. The pump drive mechanism 5 supplies gas to the circulation pump 21 to drive the circulation pump 21. The pump drive mechanism 5 is controlled by the control device 110 (control unit 111). Specifically, the pump drive mechanism 5 includes: a first pipe 51, a second pipe 52, a third pipe 53, a fourth pipe 54, a pressure adjustment valve 55, and a switching valve 56. The first pipe 51 to the fourth pipe 54 are tubular members through which gas flows. Gas is supplied to the circulation pump 21 through the first pipe 51 to the fourth pipe 54. The first pipe 51 allows gas to flow to the pressure adjustment valve 55. In other words, the first pipe 51 supplies gas to the pressure adjustment valve 55. The type of gas is not particularly limited. The gas can be, for example, air or an inert gas such as nitrogen. The pressure regulating valve 55 regulates the pressure of the gas supplied to the circulation pump 21, and regulates the ejection pressure indicating the pressure of the processing liquid ejected by the circulation pump 21. Hereinafter, the pressure of the gas supplied to the circulation pump 21 may sometimes be referred to as the "gas supply pressure". Also, the ejection pressure may sometimes be referred to as the "pump ejection pressure". The magnitude (pressure value) of the pump ejection pressure is corresponding to the magnitude (pressure value) of the gas supply pressure. Therefore, when the gas supply pressure changes, the pump ejection pressure also changes. The pressure regulating valve 55 is controlled by the control device 110 (control unit 111). The pressure regulating valve 55 includes, for example, a proportional control valve. In this case, the control device 110 (control unit 111) sends a current signal or a voltage signal to the pressure regulating valve 55. The pressure regulating valve 55 increases or decreases the gas supply pressure in proportion to the current value of the current signal or the voltage value of the voltage signal. As a result, the pump ejection pressure increases or decreases in proportion to the current value of the current signal or the voltage value of the voltage signal. In the present embodiment, the pressure regulating valve 55 includes a proportional control valve, a pressure gauge, and a control circuit. The pressure gauge measures the gas supply pressure. Specifically, the pressure gauge measures the pressure of the gas sent out from the pressure regulating valve 55. The control circuit controls the proportional control valve based on the current signal or the voltage signal output from the control device 110 (control unit 111), and increases or decreases the gas supply pressure in proportion to the current value of the current signal or the voltage value of the voltage signal. Furthermore, the control circuit performs feedback control on the proportional control valve based on the measurement result of the pressure gauge. Specifically, the control circuit controls the proportional control valve in such a way that the measurement result of the pressure gauge follows the current value of the current signal or the voltage value of the voltage signal. In addition, the control circuit of the pressure regulating valve 55 can send the measurement result of the pressure gauge to the control device 110 (control unit 111). In other words, the control device 110 (control unit 111) can obtain the gas supply pressure from the pressure regulating valve 55. The second pipe 52 allows the gas sent out from the pressure regulating valve 55 to flow to the switching valve 56. In other words, the second pipe 52 supplies gas to the switching valve 56. The switching valve 56 is controlled by the control device 110 (control unit 111), and periodically switches the gas ejection destination between the third pipe 53 and the fourth pipe 54. The switching valve 56 may include, for example, a solenoid valve. The third pipe 53 allows gas to flow to the first gas chamber 68 described later with reference to FIG. 4. In other words, the third pipe 53 supplies gas to the first gas chamber 68 described later with reference to FIG. 4. The fourth pipe 54 allows gas to flow to the second gas chamber 70 described later with reference to FIG. 4. In other words, the fourth pipe 54 supplies gas to the second gas chamber 70 described later with reference to FIG. 4. Next, referring to FIG. 3, the filtration unit 27 will be described. As shown in FIG. 3, the filtration unit 27 has a filtration membrane 27a. The filtration membrane 27a captures foreign matters contained in the processing liquid. In other words, the filtration membrane 27a filters the processing liquid. Next, referring to FIG. 3, the control device 110 will be described. As shown in FIG. 3, the control device 110 further includes an input unit 113. The input unit 113 is a user interface device operated by an operator. The input unit 113 inputs an instruction (control signal) corresponding to the operator's operation to the control unit 111. Also, the input unit 113 inputs data corresponding to the operator's operation to the control unit 111. The input unit 113 may have, for example, a keyboard and a mouse. Also, the input unit 113 may have a touch sensor. The touch sensor inputs a signal indicating the operator's touch operation to the control unit 111. The touch sensor may overlap with the display surface of the display device. In this case, a graphical user interface can be constituted by the touch sensor and the display device. In the present embodiment, the control device 110 (control unit 111) controls the pressure regulating valve 55 at the start of the drive of the circulation pump 21 and performs a pressure increasing process. Here, the pressure increasing process includes a process of gradually increasing the pressure of the gas supplied to the circulation pump 21 (gas supply pressure) and gradually increasing the pump ejection pressure to the target pressure TTP. In other words, the control device 110 (control unit 111) controls the pressure regulating valve 55 at the start of the drive of the circulation pump 21 so that the gas supply pressure continuously increases with the passage of time. As a result, the pump ejection pressure continuously increases with the passage of time. For example, the control device 110 (control unit 111) gradually increases the current value of the current signal or the voltage value of the voltage signal sent to the pressure regulating valve 55. That is, the control device 110 (control unit 111) makes the current value of the current signal or the voltage value of the voltage signal sent to the pressure regulating valve 55 continuously increase with the passage of time. As a result, the pump ejection pressure gradually increases to the target pressure TTP. In addition, the target pressure TTP represents the pressure at which the circulation pump 21 ejects the processing liquid when processing the substrate W. Hereinafter, the target pressure TTP may sometimes be referred to as the "target ejection pressure TTP". Specifically, when the control device 110 (control unit 111) restarts the operation of the substrate processing device 100, it performs a pressure increasing process. By performing the pressure increasing process, the circulation of the processing liquid through the internal circulation pipe 19 and the circulation of the processing liquid through each external circulation pipe 15 are restarted. Specifically, the control device 110 (control unit 111) restarts the circulation of the processing liquid through each external circulation pipe 15 after restarting the circulation of the processing liquid through the internal circulation pipe 19. For example, when the substrate processing apparatus 100 performs a process liquid replacement operation or a reset operation from a failure, etc., the operation stops. When the operation of the substrate processing apparatus 100 stops, the circulation of the process liquid via the internal circulation pipe 19 and the circulation of the process liquid via each external circulation pipe 15 stop. The operation of the substrate processing apparatus 100 starts again after the process liquid replacement operation or the reset operation from a failure, etc. ends. The control device 110 (control unit 111) performs a pressure boosting process when the operation of the substrate processing apparatus 100 starts again, and restarts the circulation of the process liquid via the internal circulation pipe 19 and the circulation of the process liquid via each external circulation pipe 15. For example, the control device 110 (control unit 111) can perform the pressure boosting process in response to detecting the end of the process liquid replacement operation or the reset operation from a failure, etc. Alternatively, the control device 110 (control unit 111) can perform the pressure boosting process in response to the operator operating the input unit 113 to instruct the restart of the operation of the substrate processing apparatus 100. Next, referring to FIG. 4, the circulation pump 21 included in the substrate processing apparatus 100 of the present embodiment will be described. The circulation pump 21 includes, for example, a telescopic pump. FIG. 4 is a diagram showing an example of the configuration of the circulation pump 21. Specifically, FIG. 4 shows an example of the configuration of the telescopic pump. As shown in FIG. 4, the circulation pump 21 has a first pump chamber 64 and a second pump chamber 65. The first pump chamber 64 has a first gas chamber 68 and a first liquid chamber 69. The second pump chamber 65 has a second gas chamber 70 and a second liquid chamber 71. Gas flows into the first gas chamber 68 and the second gas chamber 70. Specifically, the gas flows into the first gas chamber 68 via the third pipe 53 described with reference to FIG. 3. The gas flows into the second gas chamber 70 via the fourth pipe 54 described with reference to FIG. 3. As described with reference to FIG. 3, the switching valve 56 periodically switches the gas delivery destination between the third pipe 53 and the fourth pipe 54. Therefore, the gas alternately flows into the first gas chamber 68 and the second gas chamber 70. The process liquid flows into the first liquid chamber 69 and the second liquid chamber 71. Specifically, the volumes of the first gas chamber 68 and the second gas chamber 70 are respectively variable. Also, the volumes of the first liquid chamber 69 and the second liquid chamber 71 are respectively variable. When gas flows into the first gas chamber 68, the process liquid is sent out from the first liquid chamber 69 toward the inflow pipe 13, and the process liquid flows into the second liquid chamber 71. Specifically, when gas flows into the first gas chamber 68 and the volume of the first gas chamber 68 expands, the volume of the first liquid chamber 69 shrinks, and the process liquid is sent out from the first liquid chamber 69 toward the inflow pipe 13. Also, when the volume of the first gas chamber 68 expands, the volume of the second liquid chamber 71 expands, and the process liquid is sucked into the second liquid chamber 71. Similarly, when gas flows into the second gas chamber 70, the process liquid is sent out from the second liquid chamber 71 toward the inflow pipe 13, and the process liquid flows into the first liquid chamber 69. Specifically, as shown in FIG. 4, in addition to the first pump chamber 64 and the second pump chamber 65, the circulation pump 21 further includes: a first cylinder head 61a, a second cylinder head 61b, a pump head 62, a first cylinder 63a, a second cylinder 63b, a first moving member 66a, a second moving member 66b, a first bellows 67a, a second bellows 67b, a first liquid introduction port 72, a second liquid introduction port 73, and a liquid discharge port 74. The first pump chamber 64 is delimited by the first cylinder head 61a, the pump head 62, and the first cylinder 63a. The first cylinder 63a is disposed between the first cylinder head 61a and the pump head 62. Similarly, the second pump chamber 65 is delimited by the second cylinder head 61b, the pump head 62, and the second cylinder 63b. The second cylinder 63b is disposed between the second cylinder head 61b and the pump head 62. The first moving member 66a and the first bellows 67a are disposed within the first pump chamber 64. The second moving member 66b and the second bellows 67b are disposed within the second pump chamber 65. The first moving member 66a and the second moving member 66b are substantially circular plate-shaped. The first bellows 67a and the second bellows 67b are telescopically movable. For example, the first bellows 67a and the second bellows 67b are made of resin. One end of the first bellows 67a is connected to the first moving member 66a, and the other end of the first bellows 67a is fixed to the pump head 62. Similarly, one end of the second bellows 67b is connected to the second moving member 66b, and the other end of the second bellows 67b is fixed to the pump head 62. The first bellows 67a delimits a first gas chamber 68 and a first liquid chamber 69 within the first pump chamber 64. Specifically, within the first pump chamber 64, the space outside the first bellows 67a is the first gas chamber 68. Within the first pump chamber 64, the space inside the first bellows 67a is the first liquid chamber 69. Similarly, the second bellows 67b delimits a second gas chamber 70 and a second liquid chamber 71 within the second pump chamber 65. The pump head 62 is a housing that houses the first liquid introduction port 72, the second liquid introduction port 73, and the liquid discharge port 74. The first liquid introduction port 72 introduces the processing liquid into the first liquid chamber 69. The second liquid introduction port 73 introduces the processing liquid into the second liquid chamber 71. Specifically, the processing liquid flowing from the processing liquid tank 11 into the inflow pipe 13 is introduced into the first liquid chamber 69 and the second liquid chamber 71 via the first liquid introduction port 72 and the second liquid introduction port 73. The liquid discharge port 74 discharges the processing liquid from the first liquid chamber 69 and the second liquid chamber 71. The processing liquid discharged from the first liquid chamber 69 and the second liquid chamber 71 is sent to the inflow pipe 13 via the liquid discharge port 74. When gas is supplied to the second gas chamber 70 of the current dynasty and the pressure in the second gas chamber 70 increases, due to this pressure, the second moving member 66b in the second pump chamber 65 moves toward the pump head 62 side. As a result, the volume of the second gas chamber 70 expands, and on the other hand, the volume of the second liquid chamber 71 shrinks, and the processing liquid in the second liquid chamber 71 is sent out from the liquid outlet port 74. In conjunction with this, the first moving member 66a in the first pump chamber 64 moves toward the first cylinder head 61a side. As a result, the volume of the first gas chamber 68 shrinks, and on the other hand, the volume of the first liquid chamber 69 expands, and the processing liquid is inhaled into the first liquid chamber 69 from the first liquid inlet port 72. Similarly, when gas is supplied to the first gas chamber 68 and the pressure in the first gas chamber 68 increases, due to this pressure, the first moving member 66a in the first pump chamber 64 moves toward the pump head 62 side. As a result, the volume of the first gas chamber 68 expands, and on the other hand, the volume of the first liquid chamber 69 shrinks, and the processing liquid in the first liquid chamber 69 is sent out from the liquid outlet port 74. In conjunction with this, the second moving member 66b in the second pump chamber 65 moves toward the second cylinder head 61b side. As a result, the volume of the second gas chamber 70 shrinks, and on the other hand, the volume of the second liquid chamber 71 expands, and the processing liquid is inhaled into the second liquid chamber 71 from the second liquid inlet port 73. As described above, as shown in reference to FIG. 4, the first moving member 66a moves by the gas flowing into the first gas chamber 68, causing the volume of the first gas chamber 68 and the volume of the first liquid chamber 69 to change. Similarly, the second moving member 66b moves by the gas flowing into the second gas chamber 70, causing the volume of the second gas chamber 70 and the volume of the second liquid chamber 71 to change. Specifically, by alternately supplying gas to the first gas chamber 68 and the second gas chamber 70, the first moving member 66a and the second moving member 66b reciprocate, the volume of the first gas chamber 68 and the volume of the second gas chamber 70 alternately expand and contract, and the volume of the first liquid chamber 69 and the volume of the second liquid chamber 71 alternately expand and contract. As a result, the processing liquid alternately flows into the first liquid chamber 69 and the second liquid chamber 71, and the processing liquid is alternately sent out from the first liquid chamber 69 and the second liquid chamber 71. The processing liquid sent out from the first liquid chamber 69 and the second liquid chamber 71 is sent to the inflow pipe 13 via the liquid outlet port 74. In addition, the circulation pump 21 is not limited to a reciprocating pump. The circulation pump 21 may be any pump that is driven by the supplied gas. For example, the circulation pump 21 may be a diaphragm pump. Next, with reference to FIGS. 1 to 5, the substrate processing apparatus 100 and the substrate processing method of the present embodiment will be described. The substrate processing method of the present embodiment is executed by the substrate processing apparatus 100 described with reference to FIGS. 1 to 4. FIG. 5 is a diagram showing the flow of the substrate processing method of the present embodiment. Specifically, FIG. 5 shows the flow of the process executed by the control device 110 (control unit 111). Specifically, FIG. 5 shows the process of restarting the circulation of the processing liquid (circulation restart process). The process (circulation restart process) shown in FIG. 5 starts by restarting the operation of the substrate processing apparatus 100. As shown in FIG. 5, when restarting the operation of the substrate processing apparatus 100, the control device 110 (control unit 111) performs first valve control (step S1). In the present embodiment, the first valve control controls the following processes: controlling the circulation control mechanism 28 (the internal circulation valve 33 and a plurality of external circulation valves 29) to cause the processing liquid to flow in the internal circulation pipe 19 when the circulation pump 21 starts driving. Specifically, before restarting the operation of the substrate processing apparatus 100, the internal circulation valve 33 and the plurality of external circulation valves 29 are in a closed state, and the control device 110 (control unit 111) performs the first valve control when the operation of the substrate processing apparatus 100 is restarted, and changes the internal circulation valve 33 from the closed state to the open state. After the control device 110 (control unit 111) performs the first valve control, it starts driving the circulation pump 21 to restart the circulation of the processing liquid (step S2). At this time, the plurality of external circulation valves 29 remain in the closed state, and the internal circulation valve 33 is in the open state. Therefore, when the driving of the circulation pump 21 starts, the processing liquid flows in the internal circulation pipe 19. Further, the control device 110 (control unit 111) performs the pressure increasing process described with reference to FIG. 3 to start driving the circulation pump 21. Specifically, the control device 110 (control unit 111) controls the pressure regulating valve 55 to gradually increase the pressure of the gas supplied to the circulation pump 21 (pump supply pressure) so that the pump ejection pressure gradually increases to the target ejection pressure TTP. After the control device 110 (control unit 111) starts the pressure increasing process, it determines whether to switch the path through which the processing liquid flows (circulates) from the internal circulation pipe 19 to the external circulation pipe 15 (step S3). Hereinafter, the path through which the processing liquid flows may sometimes be referred to as the "circulation path". For example, the control device 110 (control unit 111) can determine whether to switch the circulation path from the internal circulation pipe 19 to the external circulation pipe 15 based on whether the pump ejection pressure is equal to or higher than the target ejection pressure TTP. Specifically, the control device 110 (control unit 111) can determine whether to switch the circulation path from the internal circulation pipe 19 to the external circulation pipe 15 based on whether the gas supply pressure is equal to or higher than the pressure TAP corresponding to the target ejection pressure TTP. Hereinafter, the pressure TAP may sometimes be referred to as the "target supply pressure TAP". In the case of determining whether to switch the circulation path based on the gas supply pressure, when the control device 110 (control unit 111) determines that the gas supply pressure is not equal to or higher than the target supply pressure TAP, it is determined not to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15 (No in step S3). In other words, when the control device 110 (control unit 111) determines that the gas supply pressure does not reach the target supply pressure TAP, it is determined not to switch the circulation path. Further, when the control device 110 (control unit 111) determines that the gas supply pressure is equal to or higher than the target supply pressure TAP, it is determined to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15 (Yes in step S3). When the control device 110 (control unit 111) determines not to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15 (No in step S3), the process of step S3 is repeated. For example, the control device 110 (control unit 111) repeats the process of step S3 until the gas supply pressure is equal to or higher than the target supply pressure TAP. When the control device 110 (control unit 111) determines to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15 (Yes in step S3), the second valve control is executed (step S4). As a result, the process shown in FIG. 5 ends. Here, the second valve control includes the following process: controlling the circulation control mechanism 28 (inner circulation valve 33 and a plurality of outer circulation valves 29) to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15. Specifically, the control device 110 (control unit 111) changes the inner circulation valve 33 from the open state to the closed state, and changes each outer circulation valve 29 from the closed state to the open state. As a result, the circulation of the processing liquid through the inner circulation pipe 19 stops, and the circulation of the processing liquid through each outer circulation pipe 15 starts. Next, with reference to FIGS. 1 to 5 and FIGS. 6A to 6D, the substrate processing apparatus 100 and the substrate processing method of the present embodiment will be described. FIGS. 6A and 6B are timing charts showing the operations of the inner circulation valve 33 and each outer circulation valve 29 at the restart of the operation of the substrate processing apparatus 100, respectively. Specifically, FIGS. 6A and 6B are timing charts showing the operations of the inner circulation valve 33 and each outer circulation valve 29 when the circulation of the processing liquid is restarted. FIGS. 6C and 6D are timing charts showing the pump ejection pressure and the gas supply pressure at the restart of the operation of the substrate processing apparatus 100, respectively. Specifically, FIGS. 6C and 6D are timing charts showing the pump ejection pressure and the gas supply pressure when the circulation of the processing liquid is restarted. In addition, in FIGS. 6A to 6D, the horizontal axis represents time t. Also, in FIG. 6C, the vertical axis represents the pump ejection pressure. In FIG. 6D, the vertical axis represents the gas supply pressure. As shown in FIGS. 6A to 6D, when the operation of the substrate processing apparatus 100 restarts, the control device 110 (control unit 111) changes the internal circulation valve 33 from the closed state to the open state (time t1). After that, the control device 110 (control unit 111) starts driving the circulation pump 21 (time t2). Specifically, the control device 110 (control unit 111) controls the pressure regulating valve 55 to start supplying gas to the circulation pump 21 (time t2). As a result, the circulation pump 21 starts pumping the processing liquid (time t2), and the circulation of the processing liquid through the internal circulation pipe 19 starts. In detail, the control device 110 (control unit 111) starts the pressure increasing process to gradually increase the gas supply pressure (from time t2 to time t3). As a result, the pump ejection pressure gradually increases (from time t2 to time t3). In other words, by the pressure increasing process, the gas supply pressure increases in a ramp shape. As a result, the pump ejection pressure also increases in a ramp shape. In addition, the gas supply pressure (pressure SAP) when starting to supply gas to the circulation pump 21 is preset. In other words, the opening degree of the pressure regulating valve 55 when starting to supply gas to the circulation pump 21 is preset. When the pump ejection pressure reaches the target ejection pressure TTP (time t3), the control device 110 (control unit 111) ends the pressure increasing process. For example, when the gas supply pressure reaches the target supply pressure TAP, the control device 110 (control unit 111) ends the pressure increasing process. After the pump ejection pressure reaches the target ejection pressure TTP, the pump ejection pressure is maintained at the target ejection pressure TTP (after time t3). When ending the pressure increasing process, the control device 110 (control unit 111) changes each external circulation valve 29 from the closed state to the open state (time t3). After that, the control device 110 (control unit 111) changes the internal circulation valve 33 from the open state to the closed state (time t4). As a result, the circulation path is switched from the path through the internal circulation pipe 19 to the path through each external circulation pipe 15. Next, with reference to FIGS. 7A to 7C, another example of the substrate processing apparatus 100 and the substrate processing method of the present embodiment will be described. In the embodiment described with reference to FIGS. 1 to 5 and FIGS. 6A to 6D, the substrate processing apparatus 100 includes the internal circulation pipe 19 and the internal circulation valve 33, but the internal circulation pipe 19 and the internal circulation valve 33 can be omitted. In this case, the circulation control mechanism 28 may include only a plurality of external circulation valves 29 among the plurality of external circulation valves 29 and the internal circulation valve 33. FIG. 7A is a timing chart showing another example of the operation of each external circulation valve 29 at the restart of the operation of the substrate processing apparatus 100. Specifically, FIG. 7A is a timing chart showing another example of the operation of each external circulation valve 29 when restarting the circulation of the processing liquid. FIGS. 7B and 7C are timing charts showing another example of the pump ejection pressure and the gas supply pressure at the restart of the operation of the substrate processing apparatus 100, respectively. The timing charts of the pump ejection pressure and the gas supply pressure shown in FIGS. 7B and 7C are substantially the same as the timing charts shown in FIGS. 6C and 6D. In addition, in FIGS. 7A to 7C, the horizontal axis represents time t. As shown in FIGS. 7A to 7C, in the configuration in which the internal circulation pipe 19 and the internal circulation valve 33 are omitted, the control device 110 (control unit 111) changes each external circulation valve 29 from the closed state to the open state (time t1) at the restart of the operation of the substrate processing apparatus 100. After that, the control device 110 (control unit 111) starts driving the circulation pump 21 (time t2). Then, when the pump ejection pressure reaches the target ejection pressure TTP (time t3), the control device 110 (control unit 111) ends the pressure boosting process. As described above, with reference to FIGS. 1 to 5, FIGS. 6A to 6D, and FIGS. 7A to 7C, Embodiment 1 of the present invention has been described. According to Embodiment 1, when restarting the circulation of the processing liquid, the pump ejection pressure gradually increases. Therefore, when restarting the circulation of the processing liquid, the pressure applied to the filter unit 27 (filter membrane 27a) gradually increases. Thus, it is possible to avoid a large pressure being applied to the filter unit 27 (filter membrane 27a) all at once when restarting the circulation of the processing liquid. As a result, when restarting the circulation of the processing liquid, it is difficult to release the foreign matter captured by the filter unit 27 (filter membrane 27a) from the filter unit 27. Therefore, an increase in foreign matter adhering to the substrate W when restarting the circulation of the processing liquid can be suppressed. [Embodiment 2] Next, with reference to FIGS. 3, 5, and 8A to 8D, Embodiment 2 of the present invention will be described. However, matters different from those in Embodiment 1 will be described, and the description of matters the same as those in Embodiment 1 will be omitted. Embodiment 2 is different from Embodiment 1 in that the circulation path is switched during the execution of the pressure boosting process. First, with reference to FIGS. 3 and 5, the substrate processing apparatus 100 and the substrate processing method of Embodiment 2 will be described. In Embodiment 2, the process of step S3 shown in FIG. 5 is different from that in Embodiment 1. In the present embodiment, the control device 110 (control unit 111) controls the circulation control mechanism 28 during the process of gradually increasing the pump ejection pressure by boosting processing, stops the circulation of the processing liquid through the internal circulation pipe 19, and starts the circulation of the processing liquid through each external circulation pipe 15. Specifically, the control device 110 (control unit 111) controls each external circulation valve 29 and the internal circulation valve 33 during the process of gradually increasing the pump ejection pressure by boosting processing, stops the flow of the processing liquid in the internal circulation pipe 19, and starts the flow of the processing liquid in each external circulation pipe 15. Specifically, in step S3 shown in FIG. 5, the control device 110 (control unit 111) determines to switch the circulation path from the internal circulation pipe 19 to the external circulation pipe 15 (YES in step S3) during the process of gradually increasing the pump ejection pressure. As a result, the control device 110 (control unit 111) executes the second valve control (step S4) during the boosting processing. Specifically, the control device 110 (control unit 111) changes the internal circulation valve 33 from the open state to the closed state and changes each external circulation valve 29 from the closed state to the open state during the process of gradually increasing the pump ejection pressure by boosting processing. For example, the control device 110 (control unit 111) can determine whether to switch the circulation path from the internal circulation pipe 19 to the external circulation pipe 15 based on whether the pump ejection pressure is equal to or higher than the pressure MTP. Here, the pressure MTP represents a pressure value lower than the target ejection pressure TTP. Hereinafter, the pressure MTP may sometimes be referred to as the "intermediate ejection pressure MTP". Specifically, the control device 110 (control unit 111) can determine whether to switch the circulation path from the internal circulation pipe 19 to the external circulation pipe 15 based on whether the gas supply pressure is equal to or higher than the pressure MAP corresponding to the intermediate ejection pressure MTP. Hereinafter, the pressure MAP may sometimes be referred to as the "intermediate supply pressure MAP". Next, with reference to FIGS. 3, 5, and 8A to 8D, the substrate processing apparatus 100 and the substrate processing method of the present embodiment will be described. FIGS. 8A and 8B are timing charts showing the operations of the internal circulation valve 33 and each external circulation valve 29 at the time of restarting the operation of the substrate processing apparatus 100, respectively. Specifically, FIGS. 8A and 8B are timing charts showing the operations of the internal circulation valve 33 and each external circulation valve 29 at the time of restarting the circulation of the processing liquid, respectively. FIGS. 8C and 8D are timing charts showing the pump ejection pressure and the gas supply pressure at the time of restarting the operation of the substrate processing apparatus 100, respectively. Specifically, FIGS. 8C and 8D are timing charts showing the pump ejection pressure and the gas supply pressure at the time of restarting the circulation of the processing liquid, respectively. In addition, in FIGS. 8A to 8D, the horizontal axis represents the time t. Also, in FIG. 8C, the vertical axis represents the pump ejection pressure. In FIG. 8D, the vertical axis represents the gas supply pressure. As shown in FIGS. 8A to 8D, when the operation of the substrate processing apparatus 100 restarts, the control device 110 (control unit 111) changes the internal circulation valve 33 from the closed state to the open state (time t11). After that, the control device 110 (control unit 111) starts driving the circulation pump 21 (time t12). Specifically, the control device 110 (control unit 111) controls the pressure regulating valve 55 to start supplying gas to the circulation pump 21 (time t12). As a result, the circulation pump 21 starts feeding the processing liquid (time t12), and the circulation of the processing liquid through the internal circulation pipe 19 starts. When the pump ejection pressure reaches the intermediate ejection pressure MTP (time t13), the control device 110 (control unit 111) changes each external circulation valve 29 from the closed state to the open state (time 1t3). After that, the control device 110 (control unit 111) changes the internal circulation valve 33 from the open state to the closed state (time t14). As a result, in the middle of the gradually increasing pump ejection pressure (in the middle of the pressure increasing process), the circulation path is switched from the path through the internal circulation pipe 19 to the path through each external circulation pipe 15. For example, when the gas supply pressure reaches the intermediate supply pressure MAP, the control device 110 (control unit 111) performs the second valve control to switch the circulation path. When the pump ejection pressure reaches the target ejection pressure TTP (time t15), the control device 110 (control unit 111) ends the pressure increasing process. After the pump ejection pressure reaches the target ejection pressure TTP, the pump ejection pressure is maintained at the target ejection pressure TTP (after time t15). As described above, Embodiment 2 of the present invention has been described with reference to FIGS. 3, 5, and 8A to 8D. According to Embodiment 2, similar to Embodiment 1, an increase in foreign matter adhering to the substrate W at the restart of the circulation of the processing liquid can be suppressed. Furthermore, according to Embodiment 2, before the end of the pressure increasing process, the processing liquid heated by the thermostat 25 flows through each external circulation pipe 15. Therefore, compared with the configuration in which the processing liquid flows through each external circulation pipe 15 after the end of the pressure increasing process, the temperature of each external circulation pipe 15 can be raised to the target temperature earlier. Also, compared with the configuration in which the processing liquid flows through each external circulation pipe 15 after the end of the pressure increasing process, the temperature increase of each external circulation pipe 15 by the processing liquid can start earlier. Therefore, the consumption of thermal energy can be suppressed. Even the environmental load can be reduced. [Embodiment 3] Next, referring to FIGS. 3, 9, and 10A to 10D, Embodiment 3 of the present invention will be described. However, matters different from those in Embodiments 1 and 2 will be described, and descriptions of matters the same as those in Embodiments 1 and 2 will be omitted. Different from Embodiments 1 and 2, Embodiment 3 allows the period from the start of the pressure boosting process to the end of the pressure boosting process to be variable. That is, the period during which the pump ejection pressure gradually increases by the pressure boosting process is variable. Hereinafter, the period from the start of the pressure boosting process to the end of the pressure boosting process may sometimes be referred to as the "pressure boosting period". First, referring to FIGS. 3 and 9, the substrate processing apparatus 100 and the substrate processing method of the present embodiment will be described. In the present embodiment, the storage unit 112 stores history information. The history information represents information related to the usage history of the filter unit 27. For example, as the usage history (history information) of the filter unit 27, the storage unit 112 can store the number of substrates W processed by the substrate processing apparatus 100 during the period from the start of the use of the filter unit 27 to the present. Specifically, the control unit 111 can count the number of substrates W loaded into the interior of the substrate processing apparatus 100 from the loading port LP, and store the counted value (the result of the counting) in the storage unit 112. Hereinafter, the number of substrates W processed by the substrate processing apparatus 100 during the period from the start of the use of the filter unit 27 to the present may sometimes be referred to as the "number of substrates processed". Alternatively, as the usage history (history information) of the filter unit 27, the storage unit 112 can store the flow rate of the processing liquid that has passed through the filter unit 27 during the period from the start of the use of the filter unit 27 to the present. Specifically, the substrate processing apparatus 100 may further include a flow meter provided in the inflow pipe 13. For example, the flow meter can measure the integrated flow rate. The control unit 111 stores the measurement result (integrated flow rate) of the flow meter in the storage unit 112. Hereinafter, the flow rate of the processing liquid that has passed through the filter unit 27 during the period from the start of the use of the filter unit 27 to the present may sometimes be referred to as the "total flow rate of the processing liquid". The control unit 111 adjusts the pressure boosting period based on the history information stored in the storage unit 112. Specifically, the control unit 111 adjusts the pressure boosting period based on the history information when the operation of the substrate processing apparatus 100 is restarted (when the circulation of the processing liquid is restarted). For example, the more the number of substrates processed, the further the control unit 111 extends the pressure boosting period. Alternatively, the greater the total flow rate of the processing liquid, the further the control unit 111 extends the pressure boosting period. Specifically, the greater the number of substrate processing sheets, the greater the number of foreign substances captured by the filter unit 27 (filter membrane 27a). Similarly, the greater the total flow rate of the processing liquid, the greater the number of foreign substances captured by the filter unit 27 (filter membrane 27a). On the other hand, the shorter the pressure boost period, the further the pressure applied to the filter unit 27 (filter membrane 27a) all at once becomes greater. Therefore, in a state where the number of foreign substances captured by the filter unit 27 (filter membrane 27a) is large, if the pressure boost period is shortened, the possibility that the number of foreign substances released from the filter unit 27 (filter membrane 27a) increases becomes high. In contrast, even in a state where the number of foreign substances captured by the filter unit 27 (filter membrane 27a) is large, it is difficult to release foreign substances from the filter unit 27 by further extending the pressure boost period. Specifically, the control unit 111 adjusts the pressure (pressure SAP) of the gas supplied to the circulation pump 21 at the start of the pressure boost process based on the history information. In other words, the control unit 111 adjusts the gas supply pressure (pressure SAP) when the supply of gas to the circulation pump 21 is restarted. Hereinafter, the pressure (pressure SAP) of the gas supplied to the circulation pump 21 at the start of the pressure boost process may sometimes be referred to as the "initial supply pressure SAP". The smaller the initial supply pressure SAP, the further the pressure boost period becomes longer. FIG. 9 is a diagram showing the flow of the substrate processing method of the present embodiment. Specifically, FIG. 9 shows the flow of the process executed by the control device 110 (control unit 111). Specifically, FIG. 9 shows the process of restarting the circulation of the processing liquid (circulation restarting step). The process (circulation restarting step) shown in FIG. 9 starts by restarting the operation of the substrate processing apparatus 100. The process shown in FIG. 9 includes steps S11 to step S16. As shown in FIG. 9, when restarting the operation of the substrate processing apparatus 100, the control unit 111 refers to the history information stored in the storage unit 112 (step S11). Then, the control unit 111 adjusts the pressure boost period based on the history information (step S12). Specifically, the control unit 111 adjusts the initial supply pressure SAP based on the history information. For example, the greater the number of substrate processing sheets, the further the control unit 111 reduces the pressure value of the initial supply pressure SAP. Similarly, the greater the total flow rate of the processing liquid, the further the control unit 111 reduces the pressure value of the initial supply pressure SAP. After the pressure boost period is adjusted by the control unit 111, each process of steps S13 to step S16 is executed, and the process shown in FIG. 9 ends. In addition, since each process of steps S13 to step S16 is substantially the same as each process of steps S1 to step S4 described with reference to FIG. 5, the description thereof is omitted. Next, referring to FIGS. 3, 9, and 10A to 10D, the substrate processing apparatus 100 and the substrate processing method according to the present embodiment will be described. FIGS. 10A and 10B are timing charts showing the operations of the inner circulation valve 33 and the respective outer circulation valves 29 at the restart of the operation of the substrate processing apparatus 100. Specifically, FIGS. 10A and 10B are timing charts showing the operations of the inner circulation valve 33 and the respective outer circulation valves 29 when the circulation of the processing liquid is restarted. FIGS. 10C and 10D are timing charts showing the pump ejection pressure and the gas supply pressure at the restart of the operation of the substrate processing apparatus 100. Specifically, FIGS. 10C and 10D are timing charts showing the pump ejection pressure and the gas supply pressure when the circulation of the processing liquid is restarted. In addition, in FIGS. 10A to 10D, the horizontal axis represents the time t. In FIG. 10C, the vertical axis represents the pump ejection pressure. In FIG. 10D, the vertical axis represents the gas supply pressure. In FIG. 10D, the first initial supply pressure SAP1 represents the initial supply pressure SAP at the restart of the first operation of the substrate processing apparatus 100. The second initial supply pressure SAP2 represents the initial supply pressure SAP at the restart of the second operation of the substrate processing apparatus 100. As shown in FIGS. 10A to 10D, when the operation of the substrate processing apparatus 100 is restarted, the control device 110 (control unit 111) changes the inner circulation valve 33 from the closed state to the open state (time t21). After that, the control device 110 (control unit 111) starts driving the circulation pump 21 (time t22). As a result, the circulation pump 21 starts feeding the processing liquid (time t22), and the circulation of the processing liquid through the inner circulation pipe 19 starts. Specifically, when the first operation of the substrate processing apparatus 100 is restarted, the control device 110 (control unit 111) adjusts the initial supply pressure SAP to the first initial supply pressure SAP1 based on the history information, and starts supplying gas to the circulation pump 21 (time t22). When the pump ejection pressure reaches the target ejection pressure TTP (time t23), the control device 110 (control unit 111) ends the pressure increase process. When the control device 110 (control unit 111) ends the pressure increase process, it changes each outer circulation valve 29 from the closed state to the open state (time t23). After that, the control device 110 (control unit 111) changes the inner circulation valve 33 from the open state to the closed state (time t24). As a result, the circulation path is switched from the path through the inner circulation pipe 19 to the path through the respective outer circulation pipes 15. On the other hand, when the second operation of the substrate processing apparatus 100 is restarted, the control device 110 (control unit 111) adjusts the initial supply pressure SAP to the second initial supply pressure SAP2 based on the history information, and starts the supply of gas to the circulation pump 21 (time t22). The second initial supply pressure SAP2 represents a pressure value lower than the first initial supply pressure SAP1. As a result of adjusting the initial supply pressure SAP to the second initial supply pressure SAP2, the time when the pump ejection pressure reaches the target ejection pressure TTP is delayed from time t23 to time t25. Therefore, the pressure increase period (time t21 to time t25) when the second operation of the substrate processing apparatus 100 is restarted is longer than the pressure increase period (time t21 to time t23) when the first operation of the substrate processing apparatus 100 is restarted. The control device 110 (control unit 111) ends the pressure increase process when the pump ejection pressure reaches the target ejection pressure TTP (time t25). When ending the pressure increase process, the control device 110 (control unit 111) changes each outer circulation valve 29 from the closed state to the open state (time t25). After that, the control device 110 (control unit 111) changes the inner circulation valve 33 from the open state to the closed state (time t26). As described above, Embodiment 3 of the present invention has been described with reference to FIGS. 3, 9, and 10A to 10D. According to Embodiment 3, similar to Embodiments 1 and 2, an increase in foreign matter adhering to the substrate W at the time of restarting the circulation of the processing liquid can be suppressed. Furthermore, according to Embodiment 3, the pressure increase period can be adjusted according to the usage history of the filter unit 27 (filter membrane 27a). Therefore, an increase in foreign matter adhering to the substrate W at the time of restarting the circulation of the processing liquid can be suppressed. [Embodiment 4] Next, with reference to FIGS. 11, 12, 13A to 13D, 14A to 14D, and 15, Embodiment 4 of the present invention will be described. However, matters different from Embodiments 1 to 3 will be described, and the description of matters the same as those in Embodiments 1 to 3 will be omitted. Different from Embodiments 1 to 3, Embodiment 4 performs a drainage process before executing the pressure increase process. FIG. 11 is a diagram showing the configuration of the fluid housing 101 included in the substrate processing apparatus 100 of the present embodiment. As shown in FIG. 11, the substrate processing apparatus 100 further includes a drainage mechanism 9 and a circulation regulation valve 81. The drainage mechanism 9 is housed in the fluid housing 101. The drainage mechanism 9 discharges the processing liquid from the inflow pipe 13. Specifically, the drainage mechanism 9 includes a drainage pipe 91, a drainage tank 92, and a drainage valve 93. The drain pipe 91 is a tubular member through which the processing liquid flows. The drain pipe 91 discharges the processing liquid. In the present embodiment, the drain pipe 91 discharges the processing liquid from the inflow pipe 13. Specifically, the drain pipe 91 allows the processing liquid to flow from the inflow pipe 13 to the drain tank 92. In other words, the drain pipe 91 discharges the processing liquid to the drain tank 92. More specifically, the drain pipe 91 discharges the processing liquid that has passed through the filter membrane 27a. In the present embodiment, the upstream end of the drain pipe 91 is connected to the filtration unit 27, and the downstream end of the drain pipe 91 is connected to the drain tank 92. Specifically, the upstream end of the drain pipe 91 is connected to the secondary side of the filtration unit 27. Here, the secondary side of the filtration unit 27 refers to the portion on the downstream side of the filter membrane 27a. In addition, the primary side of the filtration unit 27 refers to the portion on the upstream side of the filter membrane 27a. The drain valve 93 is disposed in the drain pipe 91 and controls the start and stop of the flow of the processing liquid in the drain pipe 91. Specifically, the drain valve 93 is an on-off valve that can be opened and closed. When the drain valve 93 is opened, the processing liquid flows in the drain pipe 91, and the processing liquid is discharged toward the drain tank 92. When the drain valve 93 is closed, the flow of the processing liquid in the drain pipe 91 stops. As a result, the discharge of the processing liquid from the inflow pipe 13 stops. The opening and closing operation of the drain valve 93 is controlled by the control device 110 (control unit 111). In the present embodiment, the circulation control mechanism 28 further includes a circulation regulating valve 81 in addition to the plurality of outer circulation valves 29 and the inner circulation valve 33. The circulation regulating valve 81 is provided in the inflow pipe 13. Specifically, the circulation regulating valve 81 is disposed between the filtration unit 27 and the second connection portion P2. In addition, in the present embodiment, the circulation control mechanism 28 includes the plurality of outer circulation valves 29, the inner circulation valve 33, and the circulation regulating valve 81. However, similar to Embodiments 1 to 3, the circulation control mechanism 28 may include only a plurality of the outer circulation valves 29 and the inner circulation valve 33 among the plurality of outer circulation valves 29, the inner circulation valve 33, and the circulation regulating valve 81. The circulation regulating valve 81 regulates the inflow of the processing liquid into the plurality of outer circulation pipes 15 and the inflow of the processing liquid into the inner circulation pipe 19. Specifically, the circulation regulating valve 81 is an on-off valve that can be opened and closed. By closing the circulation regulating valve 81, the inflow of the processing liquid into the plurality of outer circulation pipes 15 and the inflow of the processing liquid into the inner circulation pipe 19 are regulated. By opening the circulation regulating valve 81, the regulation of the inflow of the processing liquid into the plurality of outer circulation pipes 15 and the inner circulation pipe 19 is released. The opening and closing operation of the circulation regulating valve 81 is controlled by the control device 110 (control unit 111). The control device 110 (control unit 111) controls the circulation control mechanism 28 (a plurality of outer circulation valves 29, inner circulation valve 33, and circulation restriction valve 81), the pump discharge pressure, and the drain valve 93, and performs a drain process, a circulation start process, and a pressure increase process. In the present embodiment, the control device 110 (control unit 111) controls the pressure regulating valve 55 to control the pump discharge pressure. Specifically, the drain process includes the following process: when the driving of the circulation pump 21 starts, the pressure regulating valve 55 is controlled to increase the pump discharge pressure to the first target discharge pressure TTP1 (first pressure), and the circulation control mechanism 28 (a plurality of outer circulation valves 29, inner circulation valve 33, and circulation restriction valve 81) and at least the drain valve 93 among the drain valves 93 are controlled to discharge the processing liquid from the drain pipe 91. For example, when the circulation restriction valve 81 is in an open state at the start of driving of the circulation pump 21, the control device 110 (control unit 111) changes the circulation restriction valve 81 from the open state to the closed state and changes the drain valve 93 from the closed state to the open state at the start of driving of the circulation pump 21. As a result, the processing liquid is discharged toward the drain tank 92 through the drain pipe 91. Further, in the drain process, the pump discharge pressure is increased at once to the first target discharge pressure TTP1 (first pressure). In addition, the first target discharge pressure TTP1 may be a pressure higher than the pressure at which the circulation pump 21 discharges the processing liquid when processing the substrate W. Alternatively, the first target discharge pressure TTP1 may be a pressure equal to the pressure at which the circulation pump 21 discharges the processing liquid when processing the substrate W. Hereinafter, the pressure at which the circulation pump 21 discharges the processing liquid when processing the substrate W may sometimes be referred to as the "normal use pressure". The control device 110 (control unit 111) reduces the pump discharge pressure to a pressure STP (second pressure) lower than the first target discharge pressure TTP1 (first pressure) in response to discharging the processing liquid from the drain pipe 91. In other words, after executing the discharge process, the control device 110 (control unit 111) controls the pressure regulating valve 55 to reduce the pump discharge pressure to the pressure STP (second pressure). Further, the pressure STP (second pressure) represents the pump discharge pressure when the circulation of the processing liquid starts again. Hereinafter, the pressure STP (second pressure) may sometimes be referred to as the "circulation start pressure STP". The control device 110 (control unit 111) performs a circulation start process and a pressure increase process in response to reducing the pump discharge pressure from the first target discharge pressure TTP1 (first pressure) to the circulation start pressure STP (second pressure). In the present embodiment, the circulation start process includes the following process: the circulation control mechanism 28 (a plurality of outer circulation valves 29, inner circulation valve 33, and circulation restriction valve 81) and the drain valve 93 are controlled to stop the discharge of the processing liquid from the drain pipe 91 and start the circulation of the processing liquid through the inner circulation pipe 19. Specifically, the control device 110 (control unit 111) changes the circulation control valve 81 from the closed state to the open state. After that, the control device 110 (control unit 111) changes the internal circulation valve 33 from the closed state to the open state. As a result, the discharge of the processing liquid through the drain pipe 91 stops, and the circulation of the processing liquid through the internal circulation pipe 19 starts. The pressure boosting process is the same as that in Embodiments 1 to 3, and means gradually increasing the pump ejection pressure to the second target ejection pressure TTP2 (third pressure) which is greater than the circulation start pressure STP (second pressure). Here, the second target ejection pressure TTP2 represents the pressure (normal use pressure) at which the circulation pump 21 ejects the processing liquid when processing the substrate W. In addition, when the first target ejection pressure TTP1 is a pressure greater than the normal use pressure, the first target ejection pressure TTP1 represents a pressure value equal to or less than the pressure resistance value of the member or machine with the lowest pressure resistance among the members or machines provided in the inflow pipe 13, each external circulation pipe 15, and the internal circulation pipe 19. For example, when the member or machine with the lowest pressure resistance is the thermostat 25, the first target ejection pressure TTP1 represents a pressure value that is greater than the normal use pressure and equal to or less than the pressure resistance value of the thermostat 25. FIG. 12 is a diagram showing the flow of the substrate processing method of the present embodiment. Specifically, FIG. 12 shows the flow of the process executed by the control device 110 (control unit 111). Specifically, FIG. 12 shows the process of restarting the circulation of the processing liquid (circulation restarting step). The process (circulation restarting step) shown in FIG. 12 starts by restarting the operation of the substrate processing apparatus 100. As shown in FIG. 12, when restarting the operation of the substrate processing apparatus 100, the control device 110 (control unit 111) changes the drain valve 93 from the closed state to the open state (step S21). After that, the control device 110 (control unit 111) controls the circulation control mechanism 28 to regulate the circulation of the processing liquid through the plurality of external circulation pipes 15 and the circulation of the processing liquid through the internal circulation pipe 19. In the present embodiment, the control device 110 (control unit 111) changes the circulation control valve 81 from the open state to the closed state to regulate the inflow of the processing liquid into the internal circulation pipe 19 and the inflow of the processing liquid into each external circulation pipe 15 (step S22). After the control device 110 (control unit 111) changes the circulation control valve 81 from the open state to the closed state, it starts the drive of the circulation pump 21 (step S23). Specifically, the control device 110 (control unit 111) controls the pressure regulating valve 55 to start supplying gas to the circulation pump 21, and increases the pump ejection pressure to the first target ejection pressure TTP1 in one go. After the control device 110 (control unit 111) starts driving the circulation pump 21, it determines whether a specified time (first specified time) has elapsed since the start of driving the circulation pump 21 (step S24). Here, the specified time represents a preset fixed period (time). The first specified time is, for example, 30 seconds or 60 seconds. When the control device 110 (control unit 111) determines that the specified time (first specified time) has not elapsed since the start of driving the circulation pump 21 (No in step S24), it repeats the process of step S24. In other words, the control device 110 (control unit 111) maintains the pump discharge pressure at the first target discharge pressure TTP1 until the specified time (first specified time) has elapsed since the start of driving the circulation pump 21. When the control device 110 (control unit 111) determines that the specified time (first specified time) has elapsed since the start of driving the circulation pump 21 (Yes in step S24), it controls the pressure regulating valve 55 to reduce the pump discharge pressure from the first target discharge pressure TTP1 to the circulation start pressure STP (step S25). After the control device 110 (control unit 111) reduces the pump discharge pressure to the circulation start pressure STP, it performs the first valve control (step S26). In this embodiment, the first valve control includes the following processes: controlling the circulation control mechanism 28 (a plurality of outer circulation valves 29, inner circulation valve 33, and circulation restriction valve 81), and the drain valve 93 to start the circulation of the processing liquid through the inner circulation pipe 19. Specifically, the control device 110 (control unit 111) changes the circulation restriction valve 81 and the inner circulation valve 33 from the closed state to the open state, and changes the drain valve 93 from the open state to the closed state. After the control device 110 (control unit 111) performs the first valve control, it performs a pressure increase process. Specifically, the control device 110 (control unit 111) controls the pressure regulating valve 55 to gradually increase the pump discharge pressure from the circulation start pressure STP to the second target discharge pressure TTP2 (step S27). After starting the pressure increase process, the control device 110 (control unit 111) determines whether to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15 (step S28). In addition, the reason for step S28 is substantially the same as the process of step S3 shown in FIG. 5, so the detailed description is omitted. When the control device 110 (control unit 111) determines to switch the circulation path from the inner circulation pipe 19 to the outer circulation pipe 15 (Yes in step S28), it performs the second valve control (step S29). As a result, the process shown in FIG. 12 ends. In addition, the reason for step S29 is substantially the same as the process of step S4 shown in FIG. 5, so the detailed description is omitted. FIG. 13A to FIG. 13C are timing charts showing the operations of the drain valve 93, the internal circulation valve 33, and each of the external circulation valves 29 at the restart of the operation of the substrate processing apparatus 100. Specifically, FIG. 13A to FIG. 13C are timing charts showing the operations of the drain valve 93, the internal circulation valve 33, and each of the external circulation valves 29 when restarting the circulation of the processing liquid. FIG. 13D is a timing chart showing the pump ejection pressure at the restart of the operation of the substrate processing apparatus 100. Specifically, FIG. 13D is a timing chart showing the pump ejection pressure when restarting the circulation of the processing liquid. In addition, in FIGS. 13A to 13D, the horizontal axis represents the time t. Also, in FIG. 13D, the vertical axis represents the pump ejection pressure. As shown in FIGS. 13A to 13D, the control device 110 (control unit 111) performs a drainage process at the restart of the operation of the substrate processing apparatus 100. Specifically, the control device 110 (control unit 111) changes the circulation regulating valve 81 from the open state to the closed state, and changes the drain valve 93 from the closed state to the open state (time t31). After that, the control device 110 (control unit 111) starts the drive of the circulation pump 21 (time t32). As a result, the processing liquid is discharged from the inflow pipe 13 through the drain pipe 91 to the drain tank 92. In addition, when performing the drainage process, the control device 110 (control unit 111) controls the pressure regulating valve 55 to increase the pump ejection pressure to the first target ejection pressure TTP1 all at once. When a predetermined time (first predetermined time) has elapsed since the start of the drainage process, the control device 110 (control unit 111) controls the pressure regulating valve 55 to reduce the pump ejection pressure from the first target ejection pressure TTP1 to the circulation start pressure STP (time t33). After the control device 110 (control unit 111) reduces the pump ejection pressure to the circulation start pressure STP, it changes the circulation regulating valve 81 from the closed state to the open state, and changes the internal circulation valve 33 from the closed state to the open state (time t34). After that, the control device 110 (control unit 111) changes the drain valve 93 from the open state to the closed state (time t35). As a result, the discharge of the processing liquid through the drain pipe 91 stops, and the circulation of the processing liquid through the internal circulation pipe 19 starts. After the control device 110 (control unit 111) changes the drain valve 93 from the open state to the closed state, it starts a pressure increasing process (time t36). As a result, the pump ejection pressure gradually increases (time t36 to time t37). In other words, by the pressure increasing process, the pump ejection pressure increases in a ramp shape. When the pump discharge pressure reaches the second target discharge pressure TTP2 (at time t37), the control device 110 (control unit 111) ends the pressure boosting process. After the pump discharge pressure reaches the second target discharge pressure TTP2, the pump discharge pressure is maintained at the second target discharge pressure TTP2 (after time t37). When the control device 110 (control unit 111) ends the pressure boosting process, it changes each outer circulation valve 29 from the closed state to the open state (at time t37). After that, the control device 110 (control unit 111) changes the inner circulation valve 33 from the open state to the closed state (at time t38). As a result, the circulation path is switched from the path via the inner circulation pipe 19 to the path via each outer circulation pipe 15. In addition, the circulation start pressure STP includes the pressure in the state where the driving of the circulation pump 21 is stopped. That is, the control device 110 (control unit 111) can control the pressure regulating valve 55 to stop the supply of gas to the circulation pump 21 after performing the discharge process. In this case, the value of the circulation start pressure STP can be "0". According to the embodiments described with reference to FIGS. 11, 12, and 13A to 13D, at the start of driving the circulation pump 21, a pressure (first target discharge pressure TTP1) higher than the normal use pressure (the pressure at which the circulation pump 21 discharges the processing liquid when processing the substrate W) can be applied to the filter membrane 27a, and the processing liquid passing through the filter membrane 27a is discharged from the drain pipe 91. Therefore, foreign substances can be released from the filter membrane 27a before the circulation of the processing liquid is started again, and the released foreign substances are discharged together with the processing liquid. Therefore, the number of foreign substances captured by the filter membrane 27a can be reduced before the circulation of the processing liquid is started again. Therefore, an increase in foreign substances adhering to the substrate W when the circulation of the processing liquid is started again can be suppressed. Furthermore, according to the embodiments described with reference to FIGS. 11, 12, and 13A to 13D, after performing the drain process, the pump discharge pressure can be gradually increased to the second target discharge pressure TTP2 in the same manner as in Embodiments 1 to 3. Therefore, an increase in foreign substances adhering to the substrate W when the circulation of the processing liquid is started again can be suppressed. Also, according to the embodiments described with reference to FIGS. 11, 12, and 13A to 13D, the first target discharge pressure TTP1 can be set to a pressure higher than the normal use pressure. Therefore, more foreign substances can be released from the filter membrane 27a. In addition, as described with reference to FIGS. 11, 12, and 13A to 13D, when the number of foreign substances captured by the filter membrane 27a is reduced before the circulation of the processing liquid is started again, even if the pump discharge pressure is increased stepwise to the second target discharge pressure TTP2 during the pressure boosting process, an increase in foreign substances adhering to the substrate W when the circulation of the processing liquid is started again can be suppressed. Next, with reference to FIGS. 14A to 14D, another example (Example 1) of the substrate processing apparatus 100 and the substrate processing method according to the present embodiment will be described. In the embodiment described with reference to FIGS. 11, 12, and 13A to 13D, the pressure boosting process is a process of gradually (in a ramp shape) increasing the pump ejection pressure to the second target ejection pressure TTP2, but the pressure boosting process may be a process of increasing the pump ejection pressure stepwise to the second target ejection pressure TTP2. FIGS. 14A to 14C are timing charts showing another example (Example 1) of the operations of the drain valve 93, the internal circulation valve 33, and each of the external circulation valves 29 at the restart of the operation of the substrate processing apparatus 100. Specifically, FIGS. 14A to 14C are timing charts showing another example (Example 1) of the operations of the drain valve 93, the internal circulation valve 33, and each of the external circulation valves 29 when restarting the circulation of the processing liquid. FIG. 14D is a timing chart showing another example (Example 1) of the pump ejection pressure at the restart of the operation of the substrate processing apparatus 100. Specifically, FIG. 14D is a timing chart showing another example (Example 1) of the pump ejection pressure when restarting the circulation of the processing liquid. In addition, in FIGS. 14A to 14D, the horizontal axis represents time t. Also, in FIG. 14D, the vertical axis represents the pump ejection pressure. In FIGS. 14A to 14D, the operations of the drain valve 93, the internal circulation valve 33, and each of the external circulation valves 29, and the operation (pump ejection pressure) of the circulation pump 21 at each of the times t41 to t45 are substantially the same as the operations of the drain valve 93, the internal circulation valve 33, and each of the external circulation valves 29, and the operation (pump ejection pressure) of the circulation pump 21 at each of the times t31 to t35 shown in FIGS. 13A to 13D, and thus the description thereof is omitted. In Example 1 shown in FIGS. 14A to 14D, when starting the pressure boosting process (time t46), the control device 110 (control unit 111) increases the pump ejection pressure stepwise (time t46 to time t48). Specifically, when starting the pressure boosting process, the control device 110 (control unit 111) controls the pressure adjustment valve 55 to increase the pump ejection pressure from the circulation start pressure STP to the pressure XTP all at once (time t46). Here, the pressure XTP represents a pressure value that is larger than the circulation start pressure STP and smaller than the second target ejection pressure TTP2. When a predetermined time (second predetermined time) has elapsed since the pump ejection pressure was increased to the pressure XTP, the control device 110 (control unit 111) controls the pressure adjustment valve 55 to increase the pump ejection pressure from the pressure XTP to the second target ejection pressure TTP2 all at once (time t47). When the control device 110 (control unit 111) has elapsed a specified time (third specified time) since increasing the pump ejection pressure to the second target ejection pressure TTP2, it causes each external circulation valve 29 to change from the closed state to the open state (time t48). After that, the control device 110 (control unit 111) causes the internal circulation valve 33 to change from the open state to the closed state (time t49). As a result, the circulation path is switched from the path via the internal circulation pipe 19 to the path via each external circulation pipe 15. In addition, in the embodiment described with reference to FIGS. 14A to 14D, the pump ejection pressure is increased in two stages to the second target ejection pressure TTP2 during the pressure increase process, but the pump ejection pressure may be increased in three or more stages to the second target ejection pressure TTP2 during the pressure increase process. According to the embodiment described with reference to FIGS. 14A to 14D, similar to the embodiment described with reference to FIGS. 11, 12, and 13A to 13D, foreign matter can be discharged from the filter membrane 27a before restarting the circulation of the processing liquid, and the discharged foreign matter can be discharged together with the processing liquid. Therefore, the number of foreign matter captured by the filter membrane 27a can be reduced before restarting the circulation of the processing liquid. Therefore, an increase in foreign matter adhering to the substrate W when the circulation of the processing liquid is restarted can be suppressed. Next, referring to FIG. 15, another example 2 of the substrate processing apparatus 100 of the present embodiment will be described. FIG. 15 is a diagram showing another example (another example 2) of the configuration of the fluid housing 101 included in the substrate processing apparatus 100 of the present embodiment. In the configuration described with reference to FIG. 11, the upstream end of the drain pipe 91 is connected to the filter unit 27, but the upstream end of the drain pipe 91 may be connected to the inflow pipe 13 as long as it is a position where the processing liquid that has passed through the filter membrane 27a can be discharged. That is, the upstream end of the drain pipe 91 may be connected to the inflow pipe 13 on the downstream side of the filter unit 27. For example, the drain pipe 91 may be connected to the inflow pipe 13 on the upstream side of the first connection portion P1, or may be connected to the inflow pipe 13 on the upstream side of the second connection portion P2. Alternatively, as shown in FIG. 15, the drain pipe 91 may be connected to the inflow pipe 13 on the upstream side of the circulation regulating valve 81. Specifically, the drain pipe 91 may be connected to the inflow pipe 13 between the filter unit 27 and the circulation regulating valve 81. In addition, in the embodiment described with reference to FIGS. 11 to 15, after the pressure increase process ends, the circulation path is switched from the path via the internal circulation pipe 19 to the path via each external circulation pipe 15, but as described with reference to FIGS. 8A to 8D, the circulation path can be switched during the pressure increase process. Also, in the embodiment described with reference to FIGS. 11 to 15, the pressure increase period is constant, but as described with reference to FIGS. 9 and 10A to 10D, the pressure increase period can be variable. Further, in the embodiment described with reference to FIGS. 11 to 15, the circulation pump 21 is a pump driven by the pressure of a gas, but the circulation pump 21 is not limited to a pump driven by the pressure of a gas. For example, the circulation pump 21 can be a pump driven by an electric current. Alternatively, the circulation pump 21 can be a pump including a rotating body. Specifically, the circulation pump 21 can be a Levitate Electronics pump. Further, in the embodiment described with reference to FIGS. 11 to 15, the substrate processing apparatus 100 includes an internal circulation pipe 19 and an internal circulation valve 33, but the internal circulation pipe 19 and the internal circulation valve 33 can be omitted. In the case where the internal circulation pipe 19 and the internal circulation valve 33 are omitted, the circulation of the processing liquid via the external circulation pipe 15 starts by the circulation start process. As described above, the embodiments of the present invention have been described with reference to the drawings (FIGS. 1 to 15). However, the present invention is not limited to the above-described embodiments and can be implemented in various forms without departing from the gist. Further, a plurality of constituent elements disclosed in the above-described embodiments can be appropriately changed. For example, one constituent element among all the constituent elements shown in one embodiment can be added to the constituent elements of another embodiment, or several constituent elements among all the constituent elements shown in one embodiment can be deleted from the embodiment. In order to facilitate understanding of the invention, the drawings schematically show each constituent element on the whole, and the thickness, length, number, interval, etc. of each constituent element shown may be different from the actual ones for convenience in making the drawings. Further, the constitution of each constituent element shown in the above-described embodiment is an example and is not particularly limited, and of course, various changes can be made without substantially departing from the effects of the present invention. For example, in the embodiment described with reference to FIGS. 1 to 15, the substrate processing apparatus 100 includes a pulse damper 23, but in the case where a pump that does not cause pulsation of the processing liquid is used as the circulation pump 21, the pulse damper 23 can be omitted. Further, in the embodiment described with reference to FIGS. 1 to 15, the substrate processing apparatus 100 includes a thermostat 25, but in the case where the substrate processing is substrate processing that does not use a heated processing liquid, the thermostat 25 can be omitted. Further, in the embodiment described with reference to FIGS. 1 to 15, the substrate processing apparatus 100 is a single-wafer type apparatus, but the substrate processing apparatus 100 can be a batch type apparatus. [Industrial Applicability] The present invention is useful for an apparatus for processing a substrate and a method for processing a substrate. [Related Applications] This application claims priority based on Japanese Patent Application No. 2023-108182 filed on June 30, 2023, and all the inventive content of this invention application is incorporated herein by reference. 2: Substrate processing unit 4: Chamber 5: Pump drive mechanism 6: Rotating chuck 8: Ejection nozzle 9: Drain mechanism 11: Processing liquid tank 13: Inflow pipe 15: External circulation pipe 17: Individual supply pipe 19: Internal circulation pipe 21: Circulation pump 23: Pulse damper 25: Thermostat 27: Filter unit 27a: Filter membrane 28: Circulation control mechanism 29: External circulation valve 31: Individual valve 33: Internal circulation valve 51: First pipe 52: Second pipe 53: Third pipe 54: Fourth pipe 55: Pressure regulating valve 56: Switching valve 61a: First cylinder head 61b: Second cylinder head 62: Pump head 63a: First cylinder 63b: Second cylinder 64: First pump chamber 65: Second pump chamber 66a: First moving member 66b: Second moving member 67a: First bellows 67b: Second bellows 68: First gas chamber 69: First liquid chamber 70: Second gas chamber 71: Second liquid chamber 72: First liquid inlet port 73: Second liquid inlet port 74: Liquid outlet port 81: Circulation restriction valve 91: Drain pipe 92: Drain tank 93: Drain valve 100: Substrate processing device 101: Fluid housing 102: Fluid tank 110: Control device 111: Control unit 112: Memory unit 113: Input unit CR: Central robot IR: Indexer robot LP: Loading port MAP: Intermediate supply pressure / pressure MTP: Intermediate ejection pressure / pressure P1: First connection part / connection part P2: Second connection part / connection part S1~S4, S11~S16, S21~S29: Steps SAP: Pressure / Initial supply pressure SAP1: First initial supply pressure SAP2: Second initial supply pressure STP: Circulation start pressure / pressure TAP: Target supply pressure / pressure TTP: Target ejection pressure / target pressure TTP1: First target ejection pressure TTP2: Second target ejection pressure TW: Tower t, t1~t4, t11~t15, t21~t26, t31~t38, t41~t49: Time W: Substrate XTP: Pressure FIG. 1 is a schematic top view of the substrate processing apparatus according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing the configuration of a substrate processing unit, a fluid tank, and a fluid housing included in the substrate processing apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing the configuration of the fluid housing included in the substrate processing apparatus according to Embodiment 1 of the present invention. FIG. 4 is a diagram showing an example of the configuration of a circulation pump. FIG. 5 is a diagram showing the flow of the substrate processing method according to Embodiment 1 of the present invention. FIG. 6A is a timing chart showing the operation of the internal circulation valve when the operation of the substrate processing apparatus is restarted. FIG. 6B is a timing chart showing the operations of the respective external circulation valves when the operation of the substrate processing apparatus is restarted. FIG. 6C is a timing chart showing the pump ejection pressure when the operation of the substrate processing apparatus is restarted. FIG. 6D is a timing chart showing the gas supply pressure when the operation of the substrate processing apparatus is restarted. FIG. 7A is a timing chart showing another example of the operations of the respective external circulation valves when the operation of the substrate processing apparatus is restarted. FIG. 7B is a timing chart showing another example of the pump ejection pressure when the operation of the substrate processing apparatus is restarted. FIG. 7C is a timing chart showing another example of the gas supply pressure when the operation of the substrate processing apparatus is restarted. FIG. 8A is a timing chart showing the operation of the internal circulation valve when the operation of the substrate processing apparatus is restarted. FIG. 8B is a timing chart showing the operations of the respective outer circulation valves when the operation of the substrate processing apparatus is restarted. FIG. 8C is a timing chart showing the pump ejection pressure when the operation of the substrate processing apparatus is restarted. FIG. 8D is a timing chart showing the gas supply pressure when the operation of the substrate processing apparatus is restarted. FIG. 9 is a diagram showing the flow of the substrate processing method according to Embodiment 3 of the present invention. FIG. 10A is a timing chart showing the operation of the internal circulation valve when the operation of the substrate processing apparatus is restarted. FIG. 10B is a timing chart showing the operations of the respective external circulation valves when the operation of the substrate processing apparatus is restarted. FIG. 10C is a timing chart showing the pump ejection pressure when the operation of the substrate processing apparatus is restarted. FIG. 10D is a timing chart showing the gas supply pressure when the operation of the substrate processing apparatus is restarted. FIG. 11 is a diagram showing the configuration of the fluid housing included in the substrate processing apparatus according to Embodiment 4 of the present invention. FIG. 12 is a diagram showing the flow of the substrate processing method according to Embodiment 4 of the present invention. FIG. 13A is a timing chart showing the operation of the drain valve when the operation of the substrate processing apparatus is restarted. FIG. 13B is a timing chart showing the operation of the internal circulation valve when the operation of the substrate processing apparatus is restarted. FIG. 13C is a timing chart showing the operations of the respective external circulation valves when the operation of the substrate processing apparatus is restarted. FIG. 13D is a timing chart showing the pump ejection pressure when the operation of the substrate processing apparatus is restarted. FIG. 14A is a timing chart showing another example (Another Example 1) of the operation of the drain valve when the operation of the substrate processing apparatus is restarted. FIG. 14B is a timing chart showing another example (Another Example 1) of the operation of the internal circulation valve when the operation of the substrate processing apparatus is restarted.FIG. 14C is a timing chart showing another example (Example 1) of the operation of each outer circulation valve at the restart of the operation of the substrate processing apparatus. FIG. 14D is a timing chart showing another example (Example 1) of the pump ejection pressure at the restart of the operation of the substrate processing apparatus. FIG. 15 is a diagram showing another example (Example 2) of the configuration of the fluid housing included in the substrate processing apparatus according to Embodiment 4 of the present invention. 5: Pump drive mechanism 11: Processing liquid tank 13: Inflow pipe 15: Outer circulation pipe 19: Inner circulation pipe 21: Circulation pump 23: Pulse damper 25: Thermostat 27: Filter section 27a: Filter membrane 28: Circulation control mechanism 29: Outer circulation valve 33: Inner circulation valve 51: First pipe 52: Second pipe 53: Third pipe 54: Fourth pipe 55: Pressure regulating valve 56: Switching valve 100: Substrate processing apparatus 101: Fluid housing 110: Control device 111: Control section 112: Memory section 113: Input section P1: First connection part / connection part P2: Second connection part / connection part

Claims

1. A substrate processing apparatus that processes a substrate using a processing liquid, comprising: a processing liquid storage unit for storing the processing liquid; an inflow pipe for supplying the processing liquid from the processing liquid storage unit; at least one circulation pipe having its upstream end connected to the inflow pipe and its downstream end connected to the processing liquid storage unit to circulate the processing liquid; a pump disposed on the inflow pipe and driven by gas pressure to circulate the processing liquid; a filter disposed on the inflow pipe to remove foreign matter from the processing liquid; a pressure regulating valve for regulating the pressure of the gas supplied to the pump and for regulating an ejection pressure representing the pressure at which the pump ejects the processing liquid; and a control unit for controlling the pressure regulating valve when the pump is started to perform a pressurization process; wherein the pressurization process includes the following process: gradually increasing the pressure of the gas supplied to the pump by controlling the pressure regulating valve, thereby gradually increasing the ejection pressure to a target pressure.

2. The substrate processing apparatus of claim 1 further includes a memory unit that stores history information relating to the usage history of the aforementioned filter unit; and the aforementioned control unit adjusts the period during which the aforementioned ejection pressure is gradually increased by the aforementioned pressurization process based on the aforementioned history information.

3. The substrate processing apparatus of claim 2, wherein the aforementioned control unit adjusts the pressure of the gas supplied to the aforementioned pump at the beginning of the aforementioned pressurization process based on the aforementioned history information, thereby adjusting the period during which the aforementioned ejection pressure gradually increases by the aforementioned pressurization process.

4. A substrate processing apparatus according to any one of claims 1 to 3, wherein the aforementioned at least one circulation pipe comprises: a first circulation pipe and a second circulation pipe shorter than the aforementioned first circulation pipe; and the aforementioned substrate processing apparatus further comprises a circulation control mechanism that controls the circulation of the aforementioned processing liquid via the aforementioned first circulation pipe and the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe; the aforementioned control unit controls the aforementioned circulation control mechanism when the aforementioned pump is started to start the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe; the aforementioned control unit controls the aforementioned circulation control mechanism during the process of gradually increasing the aforementioned ejection pressure through the aforementioned pressurization process to start the circulation of the aforementioned processing liquid via the aforementioned first circulation pipe and to stop the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe.

5. A substrate processing apparatus according to any one of claims 1 to 3, wherein the aforementioned pump has: a first gas chamber and a second gas chamber for the inflow of the aforementioned gas; and a first liquid chamber and a second liquid chamber for the inflow of the aforementioned processing liquid; wherein the volumes of the aforementioned first gas chamber and the aforementioned second gas chamber are respectively variable; the volumes of the aforementioned first liquid chamber and the aforementioned second liquid chamber are respectively variable; the aforementioned processing liquid is discharged from the aforementioned first liquid chamber to the aforementioned inflow pipe by means of the aforementioned gas flowing into the aforementioned first gas chamber; and the aforementioned processing liquid is discharged from the aforementioned second liquid chamber to the aforementioned inflow pipe by means of the aforementioned gas flowing into the aforementioned second gas chamber.

6. A substrate processing apparatus for processing a substrate using a processing liquid, comprising: a processing liquid storage unit for storing the processing liquid; an inflow pipe for the processing liquid to flow into from the processing liquid storage unit; at least one circulation pipe having an upstream end connected to the inflow pipe and a downstream end connected to the processing liquid storage unit to circulate the processing liquid; a circulation control mechanism for controlling the circulation of the processing liquid via the at least one circulation pipe; a pump disposed on the inflow pipe to allow the processing liquid to flow through; a filter unit disposed on the inflow pipe to remove foreign matter from the processing liquid; a drain pipe for discharging the processing liquid; a drain valve disposed on the drain pipe to control the flow of the processing liquid in the drain pipe; and a control unit for controlling the circulation control mechanism, a discharge pressure indicating the pressure at which the pump discharges the processing liquid, and the drain valve to perform drain processing, circulation start processing, and pressurization processing; The aforementioned filtration unit has a filter membrane for capturing the aforementioned foreign matter contained in the aforementioned processed liquid; the aforementioned drain pipe discharges the aforementioned processed liquid that has passed through the aforementioned filter membrane; the aforementioned draining process includes the following steps: when the aforementioned pump is started, the aforementioned ejection pressure is increased to a first pressure, and the aforementioned drain valve is controlled to discharge the aforementioned processed liquid from the aforementioned drain pipe; the aforementioned control unit correspondingly discharges the aforementioned processed liquid from the aforementioned drain pipe and reduces the aforementioned ejection pressure to a second pressure lower than the aforementioned first pressure; the aforementioned control unit correspondingly reduces the aforementioned ejection pressure from the aforementioned first pressure to the aforementioned second pressure, and performs the aforementioned cycle start process and the aforementioned pressure increase process; the aforementioned cycle start process includes the following steps: controlling the aforementioned cycle control mechanism and the aforementioned drain valve to stop the discharge of the aforementioned processed liquid from the aforementioned drain pipe, and to start the cycle of the aforementioned processed liquid through one of the aforementioned at least one cycle pipe; The aforementioned pressurization process includes the following processes: increasing the aforementioned ejection pressure in stages to a third pressure that is greater than the aforementioned second pressure, or gradually increasing the aforementioned ejection pressure to a third pressure that is greater than the aforementioned second pressure.

7. The substrate processing apparatus of claim 6, wherein the aforementioned drain pipe is connected to the aforementioned filter section or the aforementioned inflow pipe.

8. The substrate processing apparatus of claim 6, wherein the aforementioned drain pipe is connected to the aforementioned inflow pipe upstream of the connection point between each of the aforementioned at least one circulation pipe and the aforementioned inflow pipe.

9. The substrate processing apparatus of any one of claims 6 to 8 further includes a memory unit that stores history information relating to the usage history of the aforementioned filter unit; and the aforementioned control unit adjusts the period during which the aforementioned ejection pressure is increased in stages or gradually by means of the aforementioned pressurization process based on the aforementioned history information.

10. The substrate processing apparatus of claim 9, wherein the aforementioned control unit adjusts the pressure of the gas supplied to the aforementioned pump at the start of the aforementioned pressurization process based on the aforementioned history information, thereby adjusting the period during which the aforementioned ejection pressure gradually increases by the aforementioned pressurization process.

11. The substrate processing apparatus of any one of claims 6 to 8, wherein the aforementioned at least one circulation pipe comprises: a first circulation pipe and a second circulation pipe shorter than the aforementioned first circulation pipe; and the aforementioned circulation control mechanism controls the circulation of the aforementioned processing liquid via the aforementioned first circulation pipe and the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe; the aforementioned circulation start process comprises the following process: controlling the aforementioned circulation control mechanism to start the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe; the aforementioned control unit controls the aforementioned circulation control mechanism to start the circulation of the aforementioned processing liquid via the aforementioned first circulation pipe and to stop the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe during the aforementioned pressurization process when the aforementioned ejection pressure is increased in stages or gradually.

12. The substrate processing apparatus of any one of claims 6 to 8, wherein the aforementioned pump is driven by gas pressure.

13. The substrate processing apparatus of claim 12, wherein the pump comprises: a first gas chamber and a second gas chamber for the inflow of the aforementioned gas; and a first liquid chamber and a second liquid chamber for the inflow of the aforementioned processing liquid; wherein the volumes of the first gas chamber and the second gas chamber are respectively variable; the volumes of the first liquid chamber and the second liquid chamber are respectively variable; the processing liquid is discharged from the first liquid chamber to the inflow pipe by means of the aforementioned gas flowing into the first gas chamber; and the processing liquid is discharged from the second liquid chamber to the inflow pipe by means of the aforementioned gas flowing into the second gas chamber.

14. The substrate processing apparatus of any one of claims 6 to 8, wherein the aforementioned first pressure is greater than the aforementioned third pressure.

15. The substrate processing apparatus of any one of claims 6 to 8, wherein the aforementioned second pressure includes the pressure when the aforementioned pump is stopped.

16. A substrate processing method comprising processing the substrate by means of a substrate processing apparatus, the substrate processing apparatus comprising: a processing liquid storage unit storing processing liquid for processing the substrate; an inflow pipe for the processing liquid to flow into from the processing liquid storage unit; at least one circulation pipe having an upstream end connected to the inflow pipe and a downstream end connected to the processing liquid storage unit to circulate the processing liquid; a pump disposed on the inflow pipe and driven by gas pressure to circulate the processing liquid; a filter unit disposed on the inflow pipe to remove foreign matter from the processing liquid; and a pressure regulating valve adjusting the pressure of the gas supplied to the pump and adjusting an ejection pressure representing the pressure at which the pump ejects the processing liquid; and the substrate processing method comprising: a circulation start step, which starts driving the pump to start the circulation of the processing liquid; the circulation start step comprising a step of controlling the pressure regulating valve to perform a pressurization process when the pump starts driving. The aforementioned pressurization process includes the following process: by controlling the aforementioned pressure regulating valve, the pressure of the aforementioned gas supplied to the aforementioned pump is gradually increased, so that the ejection pressure, which represents the pressure at which the aforementioned pump ejects the aforementioned treatment liquid, is gradually increased to the target pressure.

17. The substrate processing method of claim 16 further includes the following step: adjusting the period during which the ejection pressure is gradually increased by the aforementioned pressurization process based on history information indicating information related to the usage history of the aforementioned filter section.

18. The substrate processing method of claim 16 further includes the following steps: adjusting the pressure of the gas supplied to the pump at the beginning of the pressurization process based on history information indicating information related to the usage history of the aforementioned filter section, thereby adjusting the period during which the ejection pressure gradually increases by the aforementioned pressurization process.

19. A substrate processing method according to any one of claims 16 to 18, wherein the aforementioned at least one circulation pipe comprises: a first circulation pipe and a second circulation pipe shorter than the aforementioned first circulation pipe; and the aforementioned circulation start step comprises the following steps: when the aforementioned pump is started, the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe is started; and during the process of gradually increasing the aforementioned ejection pressure through the aforementioned pressurization process, the circulation of the aforementioned processing liquid via the aforementioned first circulation pipe is started, and the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe is stopped.

20. A substrate processing method comprising processing the substrate by means of a substrate processing apparatus, the substrate processing apparatus comprising: a processing liquid storage unit storing processing liquid for processing the substrate; an inflow pipe for the processing liquid to flow into from the processing liquid storage unit; at least one circulation pipe having an upstream end connected to the inflow pipe and a downstream end connected to the processing liquid storage unit to circulate the processing liquid; a pump disposed on the inflow pipe to allow the processing liquid to flow; a filter unit disposed on the inflow pipe to remove foreign matter from the processing liquid; a drain pipe for discharging the processing liquid; wherein the filter unit has a filter membrane for capturing the aforementioned foreign matter contained in the processing liquid; the drain pipe discharging the processing liquid that has passed through the filter membrane; the substrate processing method comprising the steps of: when the pump is started, increasing the ejection pressure, which represents the pressure at which the pump ejects the processing liquid, to a first pressure, and discharging the processing liquid from the drain pipe; Corresponding to the discharge of the aforementioned treatment fluid from the aforementioned drain pipe, the aforementioned ejection pressure is reduced to a second pressure lower than the aforementioned first pressure; and corresponding to the reduction of the aforementioned ejection pressure from the aforementioned first pressure to the aforementioned second pressure, a cycle initiation process and a pressurization process are performed; the aforementioned cycle initiation process includes the following process: initiating the circulation of the aforementioned treatment fluid through one of the aforementioned at least one circulation pipe, and stopping the discharge of the aforementioned treatment fluid from the aforementioned drain pipe; the aforementioned pressurization process includes the following process: increasing the aforementioned ejection pressure in stages to a third pressure greater than the aforementioned second pressure, or gradually increasing the aforementioned ejection pressure to a third pressure greater than the aforementioned second pressure.

21. The substrate processing method of claim 20 further includes the following step: adjusting the period during which the ejection pressure is increased in stages or gradually by means of the aforementioned pressurization process based on history information that represents information related to the usage history of the aforementioned filter section.

22. The substrate processing method of claim 20 further includes the following steps: adjusting the pressure of the gas supplied to the pump at the beginning of the pressurization process based on history information indicating information related to the usage history of the aforementioned filter section, thereby adjusting the period during which the aforementioned ejection pressure gradually increases by the aforementioned pressurization process.

23. A substrate processing method according to any one of claims 20 to 22, wherein the aforementioned at least one circulation pipe comprises: a first circulation pipe and a second circulation pipe shorter than the aforementioned first circulation pipe; and the aforementioned circulation start processing comprises the following process: initiating the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe; the aforementioned substrate processing method further comprises the following steps: initiating the circulation of the aforementioned processing liquid via the aforementioned first circulation pipe and stopping the circulation of the aforementioned processing liquid via the aforementioned second circulation pipe during the process of increasing the aforementioned ejection pressure in stages or gradually by means of the aforementioned pressurization process.

24. The substrate processing method of any one of claims 20 to 22, wherein the aforementioned first pressure is greater than the aforementioned third pressure.

25. The substrate processing method of any one of claims 20 to 22, wherein the step of reducing the ejection pressure to a second pressure lower than the first pressure includes the step of stopping the drive of the pump.

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