Fine bubble generator, processing liquis supplying apparatus and substrate processing apparatus

Abstract

A technique is provided that can stabilize the generation efficiency of fine bubbles even when the flow rate of the liquid changes. The fine bubble generator includes a first tube section (21), a narrow tube section (23), a second tube section (25), and a multi-flow-path valve mechanism (27). The narrow tube section (23) is located downstream of the first tube section (21) and has a plurality of narrow flow paths (231) with a flow path cross-sectional area decreasing downstream. The second tube section (25) is located downstream of the narrow tube section (23). The multi-flow-path valve mechanism (27) is the number of flow paths in the plurality of narrow flow paths (231) that connect the first tube section (21) and the second tube section (25) in response to changes in the flow rate of the first tube section (21).

Description

Technical Field

[0001] The subject matter disclosed in this invention relates to a fine bubble generator, a processing liquid supply device, and a substrate processing device. Prior Technology

[0002] Previously, a generator for producing fine bubbles (microbubbles) was known. For example, in the device of Patent Document 1, narrow gaps and gradually widening regions are continuously provided in the flow path of the liquid. In this device, the flow velocity is increased by narrowing the liquid flow in the narrow gaps, and a lower pressure is generated compared to the low-velocity portion of the liquid flow. Then, the pressure of the liquid flow is released in the widening region directly behind the narrow gaps, thereby generating micro- or nano-sized microbubbles from water-mixed bubbles. Furthermore, Patent Document 1 also discloses that the interval of the narrow gaps is further narrowed, thereby changing the bubble size. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2021-098173. Summary of the Invention

[0004] [The problem that the invention aims to solve] However, in conventional fine bubble generators where the liquid flow rate has changed, variations in flow velocity and / or liquid pressure can lead to a decrease in the efficiency of fine bubble generation. Therefore, it is difficult to consistently generate fine bubbles of the desired size or quantity.

[0005] The purpose of this invention is to provide a technique that can stabilize the generation efficiency of fine bubbles even when the flow rate of the liquid has changed.

[0006] [Methods used to solve problems] To address the issues described above, the first embodiment is a fine bubble generator comprising: a first tube; a narrow tube located downstream of the first tube and having a plurality of narrow flow paths with a flow path cross-sectional area decreasing downstream; a second tube located downstream of the narrow tube; and a multi-flow path valve mechanism that changes the number of flow paths connecting the first tube and the second tube among the plurality of narrow flow paths in response to the flow rate of the first tube.

[0007] The second state is a detailed bubble generator as described in the first state, wherein the aforementioned multi-flow-path valve mechanism opens and closes the flow path between the aforementioned plurality of narrow flow paths and the aforementioned first tube.

[0008] The third state sample is a fine bubble generator as described in the second state sample, wherein the aforementioned first tube has: an outer cylinder, which has a plurality of connecting holes on its outer peripheral surface and is formed into a cylindrical shape extending in the axial direction; the aforementioned multi-flow valve mechanism has: a bottomed cylindrical inner cylinder, which is inserted into the interior of the aforementioned outer cylinder, is movable in the interior of the aforementioned outer cylinder along the aforementioned axial direction, and is internally connected to the aforementioned first tube, and has a plurality of through holes on its outer peripheral surface; and a force-applying part, which applies force to the aforementioned inner cylinder towards the upstream side; the aforementioned plurality of connecting holes are respectively connected to the front The flow paths are corresponding to the plurality of narrow flow paths; the lengths of the plurality of connecting holes in the outer cylinder in the axial direction are different from each other; the plurality of through holes in the inner cylinder are configured to overlap with the corresponding connecting holes in the plurality of connecting holes in the outer cylinder in the radial direction orthogonal to the axial direction; in response to the pressure of the liquid relative to the bottom of the inner cylinder, the inner cylinder moves relative to the outer cylinder in the axial direction, thereby changing the number of the plurality of through holes that overlap with the plurality of connecting holes.

[0009] The fourth state is a fine bubble generator as described in the third state, wherein the aforementioned outer cylinder is inserted into the interior of the aforementioned narrow tube; the aforementioned plurality of narrow flow paths are arranged in the radial direction with the aforementioned narrow tube and the aforementioned outer cylinder spaced apart in the circumferential direction.

[0010] The fifth state is a detailed bubble generator as described in the second state, wherein the aforementioned multi-flow valve mechanism comprises: a plurality of on / off valves for opening and closing the flow path between the aforementioned first tube and each of the aforementioned narrow flow paths or the flow path between each of the aforementioned narrow flow paths and the aforementioned second tube; a pressure sensor for detecting the internal pressure of the aforementioned first tube; and a control unit for controlling the opening and closing state of the plurality of on / off valves in response to the pressure detected by the aforementioned pressure sensor.

[0011] The sixth state sample is a processing liquid supply device, which includes: a fine bubble generator as described in the first state sample or the second state sample; and a supply unit that supplies processing liquid to the object to be processed, wherein the processing liquid includes fine bubbles generated by the fine bubble generator.

[0012] The seventh state sample is a substrate processing apparatus comprising: a support portion for supporting a substrate; a fine bubble generator as described in the first or second state sample; and a supply portion for supplying a processing liquid to the substrate supported by the support portion, wherein the processing liquid includes fine bubbles generated by the fine bubble generator.

[0013] [Invention Benefits] Based on the first to seventh states, by varying the number of narrow flow paths connecting the first and second pipe sections according to the flow rate of the first pipe section, fluctuations in flow velocity and pressure within the narrow flow paths can be reduced. Therefore, even when the flow rate of the first pipe section has changed, the generation efficiency of fine bubbles can be stabilized.

[0014] The refined bubble generator based on the third state, by adjusting the number of narrow flow paths connecting the first and second tubes using mechanical elements, eliminates the need for sensors and / or complex electronic control systems, thus simplifying the overall structure. This reduces manufacturing and maintenance costs.

[0015] The fine bubble generator based on the fifth state allows for the free setting of conditions for opening and closing multiple on / off valves by adjusting the number of narrow flow paths connected to the first and second tubes through sensor control. Therefore, the system can be easily modified to suit the generation of fine bubbles. Simple Explanation of the Diagram

[0016] [Figure 1] is a diagram showing a cleaning apparatus having a fine bubble generator in the first embodiment. [Figure 2] is a schematic cross-sectional view showing the detailed bubble generator of the first embodiment. [Figure 3] is a schematic cross-sectional view of the detailed bubble generator at the position of line AA shown in Figure 2. [Figure 4] is a schematic cross-sectional view showing the detailed bubble generator of the second embodiment. [Figure 5] is a schematic cross-sectional view of the detailed bubble generator at the BB line position shown in Figure 4. Implementation

[0017] The embodiments of the present invention are described below with reference to the accompanying drawings. Furthermore, the constituent elements described in these embodiments are merely illustrative and are not intended to limit the scope of the invention to these embodiments. For ease of understanding, the dimensions and quantities of various parts may be exaggerated or simplified in the drawings as needed.

[0018] [1. First Implementation Form] Figure 1 is a diagram showing a cleaning apparatus 100 having a fine bubble generator 1 in its first embodiment. The cleaning apparatus 100 is a substrate processing apparatus for cleaning a substrate W with cleaning water. The substrate W is supported, for example, by a transport roller (not shown), and moves continuously in a horizontal direction in one direction by the transport roller. The transport roller is an example of a support portion.

[0019] The cleaning device 100 includes a supply unit 10. The supply unit 10 includes a high-pressure nozzle 11, a supply pipe 13, a pump 15, a tank 17, and a control unit 19. The high-pressure nozzle 11 has a spray pipe 111 and a plurality of nozzle sections 113. The spray pipe 111 extends in a direction orthogonal to the transport direction of the substrate W. Cleaning water is supplied to the spray pipe 111. The plurality of nozzle sections 113 are arranged at equal intervals along the spray pipe 111. Each nozzle section 113 is designed to spray at high pressure while dispersing the cleaning water supplied from the spray pipe 111.

[0020] Supply piping 13 supplies cleaning water to the high-pressure nozzle 11. Supply piping 13 connects the storage tank 17 and the spray pipe 111 of the high-pressure nozzle 11, and supplies cleaning water to the high-pressure nozzle 11 by means of the pump 15. Storage tank 17 stores the cleaning water to be supplied to supply piping 13. In addition, cleaning water that has been used to clean the substrate W can also be recycled to storage tank 17, thereby circulating the cleaning water.

[0021] The fine bubble generator 1 is, for example, positioned midway through the supply piping 13. The fine bubble generator 1 is capable of generating fine bubbles with a diameter of less than 100 μm (micrometers), and particularly ultrafine bubbles. Furthermore, bubbles with a diameter of less than 100 μm but greater than 1 μm within the fine bubble system are called microbubbles, and bubbles with a diameter of less than 1 μm within the fine bubble system are called ultrafine bubbles. Compared to ordinary bubbles, fine bubbles are more stable and can persist in liquids for longer periods. Ultrafine bubbles within the fine bubble system are particularly useful for cleaning performance and other applications.

[0022] As shown in Figure 1, the cleaning water containing fine bubbles generated in the fine bubble generator 1 is supplied to the high-pressure nozzle 11 via the supply pipe 13. Then, the cleaning water containing fine bubbles is supplied to the substrate W from each nozzle section 113 of the high-pressure nozzle 11. Therefore, since the substrate W can be cleaned with cleaning water containing fine bubbles, high cleaning efficiency can be achieved. Furthermore, the consumption of cleaning water can be reduced, thereby reducing the environmental burden.

[0023] In the cleaning apparatus 100, the supply unit 10 supplies a processing liquid (cleaning liquid) containing fine bubbles generated by the fine bubble generator 1 to the object to be processed (substrate W). The apparatus having the fine bubble generator 1 and the supply unit 10 is equivalent to a "processing liquid supply apparatus". In addition, the apparatus having a support unit (transfer roller) for supporting the substrate W, the fine bubble generator 1 and the supply unit 10 is equivalent to a "substrate processing apparatus".

[0024] Furthermore, the fine bubble generator 1 does not necessarily need to be installed in the supply piping 13. For example, the fine bubble generator 1 can also be installed in the piping used to supply the processing liquid to the storage tank 17.

[0025] [Detailed Bubble Generator] Figure 2 is a schematic cross-sectional view of the fine bubble generator 1 showing the first embodiment. Figure 3 is a schematic cross-sectional view of the fine bubble generator 1 at the position shown by line AA in Figure 2. The white hollow arrows shown in Figure 2 indicate the flow direction of the liquid in the fine bubble generator 1. As shown in Figure 2, the fine bubble generator 1 includes a first tube section 21, a narrow tube section 23, a second tube section 25, and a multi-flow valve mechanism 27.

[0026] The first tube section 21 is located at the upstream end of the fine bubble generator 1. The narrow tube section 23 is located downstream of the first tube section 21. The second tube section 25 is located downstream of the narrow tube section 23. That is, the fine bubble generator 1 has the first tube section 21, the narrow tube section 23, and the second tube section 25 sequentially from the upstream end to the downstream end. The liquid system that has flowed into the first tube section 21 flows towards the second tube section 25 after passing through the narrow tube section 23. The upstream end of the first tube section 21 is connected to, for example, the supply pipe 13 in the cleaning device 100 via a flow path. In addition, the downstream end of the second tube section 25 is connected to, for example, the supply pipe 13 via a flow path. The first tube section 21, the narrow tube section 23, and the second tube section 25 are, for example, cylindrical. The narrow tube section 23 has an inner diameter (inner width) that is larger than that of the first tube section 21 and the second tube section 25.

[0027] The first tube section 21, the narrow tube section 23, and the second tube section 25 are arranged coaxially with axis A1 as the center. In the following description, the direction parallel to axis A1 is defined as the "axial direction". The direction from the narrow tube section 23 toward the second tube section 25 in the axial direction is defined as "one side of the axial direction", and the opposite direction to one side of the axial direction is defined as "the other side of the axial direction". In addition, the direction orthogonal to axis A1 is defined as the "radial direction". The direction in the radial direction that is close to axis A1 is defined as the "inner radial direction", and the direction in the radial direction that is away from axis A1 is defined as the "outer radial direction". In addition, the direction of rotation with axis A1 as the center is defined as the "circumferential direction".

[0028] The first tube section 21 has an outer cylinder 211. The outer cylinder 211 is formed as a bottomed cylindrical shape extending in the axial direction. The outer cylinder 211 is located at the downstream end (the end on the axial side) of the first tube section 21. The outer cylinder 211 is inserted into and fixed inside the narrow tube section 23. More specifically, as shown in Figures 2 and 3, a gap is formed between the outer cylinder 211 and the narrow tube section 23 in the radial direction, and an annular connecting member 230 is disposed in the gap. The outer cylinder 211 of the first tube section 21 is fixed at a certain position inside the narrow tube section 23 via the connecting member 230.

[0029] A plurality of (six in this example) connecting holes 213 are formed on the outer peripheral surface of the outer cylinder 211. Figure 2 shows two of the plurality of connecting holes 213, 213a and 213b. The plurality of connecting holes 213 function as passageways for liquids and connect the inside and outside of the outer cylinder 211. Here, "connection" refers to a state in which fluids can flow through.

[0030] A plurality of connecting holes 213 are arranged at equal intervals in the circumferential direction. The lengths of the plurality of connecting holes 213 in the axial direction are different from each other. For example, connecting hole 213a is longer in the axial direction than connecting hole 213b. The plurality of connecting holes 213 are, for example, circular or oblong. However, the shape of the connecting holes can also be arbitrarily changed.

[0031] The narrow tube section 23 has a plurality of (six in this example) narrow flow paths 231. The plurality of narrow flow paths 231 are arranged radially inward of the narrow tube section 23 and radially outward of the outer cylinder 211. More specifically, the plurality of narrow flow paths 231 are provided in the connecting member 230 and are formed as holes penetrating the connecting member 230 in the axial direction. The narrow flow paths 231 are flow paths whose cross-sectional area gradually decreases downstream (towards the axial direction) and then gradually increases. The outlet side (downstream side and axial side) of the plurality of narrow flow paths 231 is connected to the second tube section 25. As shown in FIG3, the plurality of narrow flow paths 231 are equally spaced in the circumferential direction on the inner side of the narrow tube section 23 and the outer side of the outer cylinder 211.

[0032] When liquid has passed through narrow flow path 231, the cross-sectional area of ​​the flow path decreases at the inlet side of narrow flow path 231, thereby increasing the liquid velocity. As the velocity increases, the liquid pressure decreases according to Bernoulli's law. Therefore, the liquid pressure decreases rapidly in narrow flow path 231. When the pressure decreases, dissolved gases (such as air) precipitate as bubbles (cavitation). Numerous tiny bubbles are generated in narrow flow path 231 due to this pressure reduction.

[0033] Furthermore, on the outlet side of the narrow flow path 231, the flow path cross-sectional area increases again, thereby reducing the liquid velocity and restoring the liquid pressure to its original level. This pressure restoration shrinks the bubbles generated in the narrow flow path 231. That is, the bubble diameter becomes extremely small. As a result, fine bubbles with a diameter of less than 1 μm are formed.

[0034] Furthermore, although the illustration is omitted, a pipe for supplying gas to the liquid can also be installed at the narrow section 23 or at a position upstream of the narrow section 23 (illustration omitted). Supplying gas to the liquid in the pipe can increase the amount of fine bubbles generated.

[0035] The outer cylinder 211 has a plurality of connecting holes 213 arranged in a one-to-one correspondence with a plurality of narrow flow paths 231. The plurality of connecting holes 213 are connected to narrow flow paths 231 that are different from each other. For example, as shown in FIG2, the narrow flow path 231a connected by the connecting hole 213a is different from the narrow flow path 231b connected by the connecting hole 213b.

[0036] [Multi-path valve mechanism] The multi-flow-path valve mechanism 27 is designed to change the number of flow paths connected to both the first pipe section 21 and the second pipe section 25 among a plurality of narrow flow paths 231, depending on the flow rate of the first pipe section 21. The multi-flow-path valve mechanism 27 is also designed to open and close flow paths upstream of the plurality of narrow flow paths 231, depending on the flow rate of the first pipe section 21. The multi-flow-path valve mechanism 27 includes an inner cylinder 31 and a force-applying part 33.

[0037] The inner cylinder 31 is a bottomed cylindrical component that is inserted into the outer cylinder 211. A small gap is formed between the inner cylinder 31 and the outer cylinder 211 in the radial direction, allowing the inner cylinder 31 to slide within the outer cylinder 211 along the axial direction. The interior of the inner cylinder 31 is connected to the outer cylinder 211 of the first tube section 21. A plurality of through holes 311 (six in this example) are provided on the outer circumferential surface of the inner cylinder 31. The plurality of through holes 311 are evenly spaced in the circumferential direction.

[0038] The force-applying part 33 applies force to the inner cylinder 31 towards the upstream side (the side of the first tube 21). The force-applying part 33 is located on one side of the axial direction relative to the inner cylinder 31. The end of the force-applying part 33 on one side of the axial direction is fixed to the bottom of the inner cylinder 211. The end of the force-applying part 33 on the other side of the axial direction is fixed to the bottom of the inner cylinder 31. The force-applying part 33 is an elastic body such as a coil spring. The inner cylinder 31 is positioned in a position where the pressure and the applied force are balanced: the pressure is the pressure of the liquid flowing from the first tube 21 into the inner cylinder 31 towards the receiving axial direction; the applied force is the applied force from the force-applying part 33 towards the receiving axial direction.

[0039] The inner cylinder 31 has a plurality of through holes 311 arranged in a one-to-one correspondence with a plurality of connecting holes 213 of the outer cylinder 211. That is, one through hole 311 corresponds to one connecting hole 213 and one narrow flow path 231. Each through hole 311 is configured to overlap with the corresponding connecting hole 213 in the radial direction by means of axial movement of the inner cylinder 31. Overlap refers to the state in which the through hole 311 is confined within the opening range of the connecting hole 213. When a specific through hole 311 overlaps with the corresponding connecting hole 213, the liquid system inside the inner cylinder 31 can enter the narrow flow path 231 corresponding to the connecting hole 213 through the through hole 311 and the connecting hole 213.

[0040] For example, in the state shown in Figure 2, the connecting hole 213a overlaps with the corresponding through hole 311a. That is, since the through hole 311a is located within the opening range of the connecting hole 213a, it is open. On the other hand, the connecting hole 213b does not overlap with the corresponding through hole 311b. That is, the through hole 311b is located outside the opening range of the connecting hole 213b and is closed by the outer cylinder 211. Therefore, the liquid system inside the inner cylinder 31 enters the narrow flow path 231a through the through hole 311a and the connecting hole 213a. On the other hand, since the through hole 311b is closed, liquid is prevented from entering the corresponding narrow flow path 231b.

[0041] When the flow rate of the first tube 21 has increased, the inner cylinder 31 slides in the axial direction, thereby overlapping the through hole 311b with the connecting hole 213b. That is, the through hole 311b is confined within the opening range of the connecting hole 213b. In this way, the liquid system inside the inner cylinder 31 can also enter the corresponding narrow flow path 231b through the through hole 311b and the connecting hole 213b. Thus, according to the fine bubble generator 1, when the flow rate of the first tube 21 increases, the number of narrow flow paths 231 connecting the first tube 21 and the second tube 25 increases, thereby dispersing the liquid and reducing pressure loss. In this way, by reducing the fluctuations in the flow rate and pressure of the liquid in each narrow flow path 231, the reduction in the fine bubble generation efficiency can be suppressed.

[0042] Furthermore, when the flow rate in the first tube 21 has decreased, the inner cylinder 31 slides in the opposite axial direction due to the force applied by the force-applying part 33. In this way, a portion of the through hole 311 is closed, thereby reducing the number of narrow flow paths 231 connecting the first tube 21 and the second tube 25. This reduces the decrease in the flow rate and pressure of the liquid passing through the narrow flow paths 231, thus suppressing the reduction in the efficiency of fine bubble formation.

[0043] As explained above, the number of narrow flow paths 231 connecting the first tube 21 and the second tube 25 is adjusted according to the flow rate of the fine bubble generator 1. Therefore, even when the flow rate of the first tube 21 changes, the generation efficiency of fine bubbles can be kept stable.

[0044] Furthermore, based on the fine bubble generator 1, the number of narrow flow paths 231 connecting the first tube 21 and the second tube 25 can be adjusted by mechanical means. Therefore, since sensors and / or complex electronic control systems are not required, the overall structure can be simplified. This reduces manufacturing and maintenance costs.

[0045] [2. Second Implementation Form] Next, the second embodiment will be described. Furthermore, in the following description, elements that have the same function as the elements already described will be given the same element symbols or additional alphabetic symbols, and detailed descriptions may be omitted.

[0046] Figure 4 is a schematic cross-sectional view showing the fine bubble generator 1A in the second embodiment. Figure 5 is a schematic cross-sectional view of the fine bubble generator 1A at the position shown by line BB in Figure 4. As shown in Figure 4, the fine bubble generator 1A has a first tube section 21, a narrow tube section 23a, and a second tube section 25 sequentially from the upstream side to the downstream side. The narrow tube section 23a has an inner diameter (inner width) that is larger than that of the first tube section 21 and the second tube section 25.

[0047] The narrow tube section 23a has a plurality of narrow flow paths 231 (seven in this example). The plurality of narrow flow paths 231 are formed in a partition member 233 disposed inside the narrow tube section 23. More specifically, a plurality of branch flow paths 235 extending in the axial direction are provided in the partition member 233. Then, a narrow flow path 231 is formed in the middle of each branch flow path 235. That is, the plurality of narrow flow paths 231 are provided in a one-to-one correspondence with the plurality of branch flow paths 235. As shown in FIG5, the plurality of branch flow paths 235 and the plurality of narrow flow paths 231 are arranged in a radially dispersed manner.

[0048] The fine bubble generator 1A includes a multi-flow-path valve mechanism 27a. The multi-flow-path valve mechanism 27a includes a plurality of (seven in this example) on / off valves 351, a pressure sensor 353, and a control unit 355. An on / off valve 351 is disposed inside each of the plurality of branch flow paths 235. That is, the plurality of on / off valves 351 are arranged in a one-to-one correspondence with the plurality of branch flow paths 235. The on / off valve 351 is, for example, a butterfly valve: rotating the disk that can close the branch flow path 235 by 90˚ opens or closes the branch flow path 235. However, the on / off valve 351 can be any type of valve as long as it can open or close the branch flow path 235. The on / off valve 351 is located upstream of the narrow flow path 231 (on the opposite side in the axial direction). That is, the on / off valve 351 has the following elements: a flow path (branch flow path 235) between the corresponding narrow flow path 231 and the first pipe section 21.

[0049] Pressure sensor 353 is installed in the first pipe section 21 to detect the internal pressure (water pressure) of the first pipe section 21. Pressure sensor 353 is electrically connected to control unit 355, converting the detected pressure into an electrical signal and outputting it to control unit 355. Control unit 355 is composed of a computer, which has a processor such as CPU (Central Processing Unit) and memory such as RAM (Random Access Memory). However, control unit 355 may also be composed of electrical circuits such as programmable logic controller (PLC), relay circuit, or PID (Proportional-Integral-Derivative) controller.

[0050] The control unit 355 dynamically controls the opening and closing states of a plurality of on / off valves 351 in response to the pressure detected by the pressure sensor 353. More specifically, each time the pressure detected by the pressure sensor 353 exceeds a predetermined threshold, the control unit 355 opens the plurality of on / off valves 351 in stages. On the other hand, each time the pressure detected by the pressure sensor 353 is lower than the predetermined threshold, the control unit 355 closes the plurality of on / off valves 351 in stages. That is, the control unit 355 controls the opening and closing states of the plurality of on / off valves 351 in a manner proportional to the pressure detected by the pressure sensor 353 and the number of on / off valves 351 opened.

[0051] When the flow rate of the first tube 21 increases, the pressure detected by the pressure sensor 353 also increases. That is, the pressure detected by the pressure sensor 353 is positively correlated with the flow rate of the first tube 21. Therefore, in the fine bubble generator 1A, a number of on / off valves 351 corresponding to the flow rate of the first tube 21 are opened. That is, a number of narrow flow paths 231 corresponding to the flow rate of the first tube 21 are connected to the first tube 21 and the second tube 25. In this way, even when the flow rate of the first tube 21 has changed, the flow rate and pressure in each narrow flow path 231 are adjusted to values ​​suitable for the generation of fine bubbles, thus stabilizing the generation efficiency of fine bubbles.

[0052] Furthermore, according to the fine bubble generator 1A, since the number of narrow flow paths 231 communicating with the first tube 21 and the second tube 25 is adjusted by sensor control, the conditions (limit values) for opening and closing the plurality of on / off valves 351 can be freely set. Therefore, the system can be easily modified to suit the generation of fine bubbles.

[0053] [3. Examples of Variation] Although the embodiments have been described above, the present invention is not limited to the above description and various changes can be made.

[0054] For example, in the fine bubble generator 1A of the second embodiment, a plurality of on / off valves 351 are arranged upstream of the corresponding narrow flow path 231, respectively opening and closing the flow path (branch flow path 235) between the first pipe section 21 and the corresponding narrow flow path 231. However, each on / off valve 351 may also be arranged downstream of the narrow flow path 231. In this case, the plurality of on / off valves 351 respectively open and close the flow path (branch flow path 235) between the corresponding narrow flow path 231 and the second pipe section 25.

[0055] Although the invention has been described in detail, the above description is merely illustrative of all embodiments, and the invention is not limited to these embodiments. It can be interpreted that numerous variations not illustrated are conceivable without departing from the spirit of the invention. The configurations described in the various embodiments and variations above can be appropriately combined or omitted as long as they do not contradict each other.

[0056] 1,1A: Fine Bubble Generator 10: Supply Department 11: High-pressure nozzle 13: Supply piping 15: Pump 17: Storage tank 19: Control Department 21: First Management Section 23, 23a: Narrow tube portion 25: Second Pipeline 27, 27a: Multi-path valve mechanism 31: Inner cylinder 33: Force-exerting part 100: Cleaning apparatus (substrate processing apparatus) 111: Spray pipe 113: Nozzle section 211:Outer cylinder 213, 213a, 213b: Connecting holes 230: Connecting structural components 231,231a,231b: Narrow flow path 233: Partitioning components 235: Branch Flow Path 311, 311a, 311b: Through holes 351: On / off valve 353: Pressure sensor 355: Control Department A1: Axis W: substrate

Claims

1. A fine bubble generator comprising: a first tube; a narrow tube located downstream of the first tube and having a plurality of narrow flow paths with a flow path cross-sectional area decreasing downstream; a second tube located downstream of the narrow tube; and a multi-flow path valve mechanism for changing the number of flow paths connecting the first tube and the second tube in the plurality of narrow flow paths according to the flow rate of the first tube.

2. The fine bubble generator as described in claim 1, wherein the aforementioned multi-flow-path valve mechanism opens and closes the flow path between the aforementioned plurality of narrow flow paths and the aforementioned first tube.

3. The fine bubble generator as described in claim 2, wherein the aforementioned first tube comprises: an outer cylinder having a plurality of connecting holes on its outer peripheral surface and being formed as a cylinder extending in the axial direction; the aforementioned multi-flow valve mechanism comprises: a bottomed cylindrical inner cylinder inserted into the interior of the aforementioned outer cylinder, capable of moving along the aforementioned axial direction within the aforementioned outer cylinder and internally connected to the aforementioned first tube, and having a plurality of through holes on its outer peripheral surface; and a force-applying part that applies force to the aforementioned inner cylinder towards the upstream side; the aforementioned plurality of connecting holes are respectively connected to corresponding flow paths in the aforementioned plurality of narrow flow paths; the lengths of the aforementioned plurality of connecting holes in the aforementioned outer cylinder in the aforementioned axial direction are different from each other; the aforementioned plurality of through holes in the aforementioned inner cylinder are configured to overlap with the corresponding connecting holes in the aforementioned plurality of connecting holes in the aforementioned outer cylinder in a radial direction orthogonal to the aforementioned axial direction; In response to the pressure of the liquid relative to the bottom of the inner cylinder, the inner cylinder moves relative to the outer cylinder in the axial direction, thereby changing the number of the aforementioned through holes that overlap with the aforementioned multiple connecting holes.

4. The fine bubble generator as described in claim 3, wherein the outer cylinder is inserted into the interior of the narrow tube; the plurality of narrow flow paths are arranged in the radial direction with the narrow tube and the outer cylinder spaced apart in the circumferential direction.

5. The fine bubble generator as described in claim 2, wherein the aforementioned multi-flow valve mechanism comprises: a plurality of on / off valves for opening and closing the flow path between the aforementioned first tube and each of the aforementioned narrow flow paths or the flow path between each of the aforementioned narrow flow paths and the aforementioned second tube; a pressure sensor for detecting the internal pressure of the aforementioned first tube; and a control unit for controlling the opening and closing state of the plurality of on / off valves in response to the pressure detected by the aforementioned pressure sensor.

6. A treatment liquid supply device comprising: a fine bubble generator as described in any one of claims 1 to 5; and a supply unit for supplying the treatment liquid to a treatment object, wherein the treatment liquid includes fine bubbles generated by the fine bubble generator.

7. A substrate processing apparatus comprising: a support portion for supporting a substrate; a fine bubble generator as described in any one of claims 1 to 5; and a supply portion for supplying a processing liquid to the substrate supported by the support portion, the processing liquid comprising fine bubbles generated by the fine bubble generator.

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