Low-pulse photoresist filtering and circulating system

Abstract

The utility model provides a low-pulse photoresist filtering and circulating system, which relates to the technical field of photoresist filtering and circulating and comprises a liquid storage tank, a circulating pump, a first buffer tank, a second buffer tank and a multi-stage filtering device, the circulating pump, the first buffer tank, the second buffer tank and the multi-stage filtering device are sequentially connected between a bottom liquid outlet of the liquid storage tank and a top liquid return opening of the liquid storage tank through pipelines; the circulating pump is used for pumping the photoresist discharged from the liquid outlet of the liquid storage tank into the first buffer tank; the first buffer tank and the second buffer tank are arranged in series and are used for temporarily storing photoresist and buffering pulse pressure fluctuation of the low-pulse photoresist filtering and circulating system; and the multi-stage filtering device is used for filtering the photoresist. According to the utility model, the two buffer tanks are arranged in series, so that the influence of pulse pressure on the filtering effect is reduced, the number of particles in photoresist is reduced, the purity and quality of the photoresist are ensured, and the system is simple in structure and relatively low in cost.

Description

Technical Field

[0001] This utility model relates to the field of photoresist filtration and circulation technology, and in particular to a low-pulse photoresist filtration and circulation system. Background Technology

[0002] Currently, in semiconductor lithography, the purity of photoresist directly affects the accuracy and yield of wafer surface patterns. Photoresist needs to be filtered and circulated to remove minute particles. Existing technologies commonly employ a single-buffer tank filtration and circulation system. During operation, a circulation pump transports the photoresist from the storage tank to the filter. The filtered photoresist is then temporarily stored in a single buffer tank before returning to the storage tank, continuing the circulation process.

[0003] However, this scheme has the following drawbacks: (1) Significant pulse effect: The start-up and shutdown of the pump, valve switching and changes in liquid flow rate will cause drastic pressure fluctuations in the pipeline (i.e., pulses). The pulse pressure will disturb the particles trapped by the filter, causing some particles to re-enter the circulation system and causing secondary pollution; (2) Insufficient buffering capacity: The traditional single buffer tank has a limited volume and cannot effectively absorb high-frequency pressure fluctuations. Especially under high-speed circulation conditions, the pulse superposition will further aggravate the release of particles; (3) Abnormal increase in particles: When the peak pulse pressure of the system is too high, the number of particles with a diameter >0.1μm in the photoresist increases by 20%~30%, which seriously affects the uniformity of the photoresist. Existing technologies usually reduce pulses by optimizing the pump control algorithm or adding a one-way valve, but the actual effect is limited and the cost is high. Therefore, there is an urgent need for a low-pulse photoresist filtration circulation system with a simple structure and controllable cost. Summary of the Invention

[0004] The purpose of this invention is to provide a low-pulse photoresist filtration and circulation system to solve at least one of the aforementioned technical problems in the prior art.

[0005] To solve the above-mentioned technical problems, this utility model provides a low-pulse photoresist filtration circulation system, comprising: a storage tank, a circulation pump, a first buffer tank, a second buffer tank, and a multi-stage filtration device;

[0006] The storage tank is used to store photoresist;

[0007] The circulating pump, the first buffer tank, the second buffer tank, and the multi-stage filtration device are connected in sequence through pipelines between the bottom outlet of the storage tank and the top return outlet of the storage tank.

[0008] The circulation pump is used to pump the photoresist discharged from the outlet of the storage tank into the first buffer tank. Then, the photoresist passes through the first buffer tank, the second buffer tank and the multi-stage filtration device in sequence, and flows back into the storage tank from the return port of the storage tank, thereby realizing the circulation of the photoresist.

[0009] The first buffer tank and the second buffer tank are connected in series to temporarily store photoresist and buffer the pulse pressure fluctuations of the low-pulse photoresist filtration circulation system.

[0010] The top of the first buffer tank is connected to a first air passage for supplying compressed air into the first buffer tank, using the constant pressure of the compressed air to eliminate pulse pressure fluctuations.

[0011] The top of the second buffer tank is connected to a second air passage for supplying compressed air into the second buffer tank, using the constant pressure of the compressed air to eliminate pulse pressure fluctuations.

[0012] The multi-stage filtration device is used to filter photoresist and remove particulate matter from it.

[0013] In use, the photoresist in the storage tank is pumped into the first buffer tank by the circulation pump; compressed air is supplied to the first buffer tank from the first air passage, compressing the gas at the top of the first buffer tank and forcing the photoresist in the first buffer tank to flow into the second buffer tank; compressed air is supplied to the second buffer tank from the second air passage, compressing the gas at the top of the second buffer tank and forcing the photoresist in the second buffer tank to flow into the multi-stage filtration device; after being filtered by the multi-stage filtration device, the photoresist flows back into the storage tank. This application increases the buffer volume by arranging two buffer tanks in series before the inlet of the multi-stage filtration device, which can effectively absorb high-frequency pulse pressure fluctuations, greatly reducing the pulse pressure peak value and pulse pressure fluctuation frequency, avoiding pulse pressure disturbance to the multi-stage filtration device, improving the filtration effect, reducing the number of particles in the photoresist, ensuring the purity and quality of the photoresist, and the system structure is simple and the cost is low.

[0014] Furthermore, the storage tank is equipped with a stirring paddle to stir the photoresist in the storage tank, ensuring that the various components in the photoresist are fully mixed and evenly distributed, which is suitable for high viscosity photoresist and avoids excessive local concentration of high viscosity photoresist, which affects the quality.

[0015] A first pneumatic motor is installed on the top of the liquid storage tank. The output shaft of the first pneumatic motor is connected to the upper end of the stirring paddle to drive the stirring paddle to rotate.

[0016] Preferably, the air inlet of the first pneumatic motor is connected to one end of the first compressed air circuit, and the other end of the first compressed air circuit is connected to a compressed air source for supplying compressed air from the first compressed air circuit to the first pneumatic motor. The compressed air in the first pneumatic motor is discharged from the exhaust port of the first pneumatic motor, thereby driving the first pneumatic motor to rotate.

[0017] Preferably, the first compressed air line is provided with a first pressure gauge and a first pressure regulating valve;

[0018] The first pressure gauge is used to detect the gas pressure flowing from the first compressed air path to the first pneumatic motor;

[0019] The first pressure regulating valve is used to regulate the flow rate and on / off state of compressed air in the first compressed air circuit, thereby regulating the speed and on / off state of the first pneumatic motor, and thus regulating the stirring rate of the stirring paddle.

[0020] In use, the first pressure regulating valve can more accurately adjust the stirring rate of the stirring paddle based on the gas pressure detected by the first pressure gauge.

[0021] Furthermore, the top of the liquid storage tank is also equipped with a ventilation valve (i.e., a breather valve) to regulate the air pressure inside the liquid storage tank, maintain the air pressure balance inside and outside the liquid storage tank, prevent the liquid storage tank from being damaged due to overpressure or negative pressure, and at the same time reduce the loss of photoresist volatilization and environmental pollution.

[0022] Preferably, the outlet of the storage tank is connected to the inlet of the circulation pump through a first pipeline, so that the photoresist discharged from the outlet of the storage tank can flow to the circulation pump;

[0023] A switching valve is installed on the first pipeline to control the flow of photoresist within the pipeline.

[0024] Preferably, a sampling valve is also provided on the first pipeline for sampling the photoresist in the first pipeline;

[0025] In use, the sampling valve is opened, and a portion of the photoresist sample in the first pipeline is extracted from the sampling valve to test the purity and quality of the photoresist.

[0026] Preferably, the circulating pump is a pneumatic diaphragm pump. The pneumatic motor of the circulating pump is connected to one end of the second compressed air circuit, and the other end of the second compressed air circuit is connected to a compressed air source. The second compressed air circuit is used to supply compressed air to the pneumatic motor of the circulating pump. The compressed air in the pneumatic motor is discharged from the exhaust port of the pneumatic motor, thereby driving the circulating pump through the pneumatic motor.

[0027] Preferably, a second pressure regulating valve is provided in the second compressed air circuit to regulate the flow rate and on / off state of the compressed air in the second compressed air circuit, thereby regulating the speed and on / off state of the pneumatic motor of the circulating pump, and further regulating the circulation flow rate of the circulating pump, controlling the working efficiency and on / off state of the circulating pump.

[0028] Furthermore, the outlet of the first buffer tank is connected to the inlet of the second buffer tank through a damping tube, which is used for the photoresist in the first buffer tank to flow into the second buffer tank. During the flow of the photoresist, vibration is reduced. When the photoresist flows through the damping tube, it rubs against the damping tube, converting kinetic energy into heat energy, consuming the energy of the pulse pressure fluctuation, and at the same time, the transmission speed of the pulse pressure fluctuation is slowed down through the damping tube.

[0029] Furthermore, the damping tube has a tapered structure, and its inner diameter gradually decreases from the outlet of the first buffer tank to the inlet of the second buffer tank, thereby increasing the flow rate of the photoresist within the damping tube and consuming the energy of pulse pressure fluctuations.

[0030] Preferably, the taper angle of the damping tube is 15°.

[0031] Furthermore, the inner wall of the damping tube is provided with a spiral guide groove, which allows the photoresist to flow along the spiral guide groove inside the damping tube, thereby extending the flow path of the photoresist inside the damping tube, increasing the friction between the photoresist and the damping tube, converting kinetic energy into heat energy, and consuming the energy of pulse pressure fluctuations.

[0032] Preferably, the depth of the guide groove is one-tenth of the inner diameter of the damping tube.

[0033] Preferably, a one-way valve is connected between the second buffer tank and the damping tube, for the photoresist in the first buffer tank to flow unidirectionally from the damping tube to the second buffer tank, preventing the photoresist in the second buffer tank from flowing back.

[0034] Furthermore, the low-pulse photoresist filtration circulation system also includes a third compressed air path, one end of which is connected to a compressed air source, and the other end is connected to the first air path and the second air path respectively through a three-way valve, for supplying compressed air from the third compressed air path to the first buffer tank and the second buffer tank respectively through the first air path and the second air path;

[0035] The third compressed air circuit is equipped with a third pressure gauge and a third pressure regulating valve.

[0036] The third pressure gauge is used to detect the gas pressure flowing from the third compressed gas path to the first buffer tank and the second buffer tank;

[0037] The third pressure regulating valve is used to regulate the flow rate and on / off state of compressed air in the third compressed air circuit, thereby regulating the gas pressure flowing from the third compressed air circuit to the first buffer tank and the second buffer tank.

[0038] In use, the third pressure regulating valve can adjust the gas pressure more accurately based on the gas pressure detected by the third pressure gauge.

[0039] Preferably, the three-way valve is provided with a flow-dividing regulating valve for adjusting and distributing the flow rate of compressed gas flowing from the third compressed gas path into the first gas path and the second gas path.

[0040] Preferably, a first flow regulating valve and a first pressure sensor are provided in the first air path;

[0041] The first flow regulating valve is used to regulate the flow rate and on / off state of the first air passage;

[0042] The first pressure sensor is connected to the top of the first buffer tank and is used to detect the gas pressure at the top of the first buffer tank, control the first flow regulating valve to regulate the flow of the first gas path, thereby regulating the gas pressure at the top of the first buffer tank.

[0043] Preferably, a second flow regulating valve and a second pressure sensor are provided in the second air path;

[0044] The second flow regulating valve is used to regulate the flow rate and on / off state of the second air passage;

[0045] The second pressure sensor is connected to the top of the second buffer tank and is used to detect the gas pressure at the top of the second buffer tank, control the second flow regulating valve to regulate the flow rate of the second gas path, thereby regulating the gas pressure at the top of the second buffer tank.

[0046] During use, the first pressure sensor and the second pressure sensor control the first flow regulating valve and the second flow regulating valve respectively to regulate the top gas pressure of the first buffer tank and the second buffer tank, thereby realizing the linkage control and adjustment of the top gas pressure of the first buffer tank and the second buffer tank, ensuring that the photoresist flows from the first buffer tank to the second buffer tank.

[0047] Preferably, a pressure balancing valve is provided at the top of the first buffer tank to adjust the gas pressure inside the first buffer tank, control the pressure difference between the gas pressure at the top of the first buffer tank and the circulation pump, and ensure that the photoresist inside the first buffer tank flows to the second buffer tank.

[0048] Furthermore, an exhaust valve is connected to the top of the first buffer tank for venting gas from the first buffer tank, and for venting and depressurizing during maintenance.

[0049] Preferably, a liquid level sensor is provided on the outside of both the first buffer tank and the second buffer tank to measure the liquid level of the photoresist inside the first buffer tank or the second buffer tank.

[0050] The liquid level sensor is equipped with a low liquid level line and a high liquid level line. When the liquid level of the photoresist in the first buffer tank and / or the second buffer tank is lower than the low liquid level line or higher than the high liquid level line, the pressure regulating device adjusts the air pressure in the first buffer tank and / or the second buffer tank, thereby maintaining the liquid level of the photoresist in the first buffer tank and the second buffer tank within a stable range.

[0051] The first buffer tank focuses on pressure buffering, while the second buffer tank focuses on flow rate stability.

[0052] Furthermore, the multi-stage filtration device includes a first filter and a second filter, wherein the first filter and the second filter are arranged in series.

[0053] Furthermore, the first filter is provided with a first filter element for coarse filtration of the photoresist, filtering out particles with larger and moderate particle sizes in the photoresist;

[0054] The second filter contains a second filter element with a smaller pore size than the first filter element. This second filter element is used for fine filtration of the photoresist, removing small and tiny particles from the photoresist.

[0055] The multi-stage filtration device gradually increases the filtration precision from the first filter to the second filter, greatly improving filtration efficiency and effectiveness, reducing the probability of clogging, extending service life, and reducing replacement frequency. The first and second filter elements with appropriate pore sizes can meet the requirements for nanoscale filtration of photoresist.

[0056] Furthermore, the outlet of the multi-stage filtration device is connected to the top return port of the storage tank via a return pipeline, so that the filtered photoresist can flow back into the storage tank from the return pipeline;

[0057] The return pipeline is provided with a filling port for the photoresist to be discharged from the filling port of the return pipeline;

[0058] The filling port is equipped with a shut-off valve for adjusting the opening and closing of the filling port. After the photoresist sample is tested and the quality and purity meet the standards, the shut-off valve is opened, and the photoresist is filled into the storage container from the filling port.

[0059] Preferably, the low-pulse photoresist filtration and circulation system further includes a balance for weighing the photoresist in the storage container.

[0060] Preferably, the low-pulse photoresist filtration circulation system further includes a fan filter unit (FFU) for filtering the filling space during photoresist filling to ensure the cleanliness of the filling space.

[0061] By adopting the above technical solution, this utility model has the following beneficial effects:

[0062] This invention provides a low-pulse photoresist filtration circulation system. By arranging two buffer tanks in series on the front side of the inlet of the multi-stage filtration device, the buffer volume is increased, which can effectively absorb high-frequency pulse pressure fluctuations, greatly reduce the pulse pressure peak value and pulse pressure fluctuation frequency, avoid pulse pressure disturbance to the multi-stage filtration device, improve the filtration effect, reduce the number of particles in the photoresist, and ensure the purity and quality of the photoresist. The system has a simple structure and low cost. Attached Figure Description

[0063] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0064] Figure 1 A schematic diagram of the structure of the low-pulse photoresist filtration circulation system provided in this embodiment of the present invention;

[0065] Figure 2 for Figure 1 A partial cross-sectional view of the damping tube shown;

[0066] Figure 3 A schematic diagram of the structure of the first buffer tank of a low-pulse photoresist filtration circulation system provided in another embodiment of the present invention;

[0067] Figure 4 This is a schematic diagram of the structure of a low-pulse photoresist filtration circulation system provided in another embodiment of the present invention.

[0068] Figure label:

[0069] 1-Storage tank; 11-Agitator; 12-First pneumatic motor; 121-First pressure gauge; 122-First pressure regulating valve; 13-Ventilation valve; 14-Switch valve; 15-Sampling valve; 2-Circulation pump; 201-Second pressure regulating valve; 301-Third pressure gauge; 302-Third pressure regulating valve; 303-Flow diversion regulating valve; 31-First buffer tank; 311-Exhaust valve; 312-First pressure sensor; 313-First flow regulating valve; 32-Second buffer tank; 321-Second pressure sensor; 322-Second flow regulating valve; 33-Damping tube; 331-Flow guide channel; 34-Check valve; 35-Level sensor; 351-Low level line; 352-High level line; 41-First filter; 42-Second filter; 43-Filling port. Detailed Implementation

[0070] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0071] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0072] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0073] The present invention will be further explained below with reference to specific embodiments.

[0074] It should also be noted that the specific embodiments or implementation methods described below are a series of optimized settings listed by this utility model to further explain the specific utility model content, and these settings can be combined or used in conjunction with each other. Example

[0075] like Figure 1-2As shown, this embodiment provides a low-pulse photoresist filtration and circulation system, including: a storage tank 1, a circulation pump 2, a first buffer tank 31, a second buffer tank 32, and a multi-stage filtration device; the storage tank 1 is used to store photoresist; the circulation pump 2, the first buffer tank 31, the second buffer tank 32, and the multi-stage filtration device are sequentially connected via pipelines between the bottom outlet of the storage tank 1 and the top return outlet of the storage tank 1; the circulation pump 2 is used to pump the photoresist discharged from the outlet of the storage tank 1 into the first buffer tank 31, and then the photoresist sequentially passes through the first buffer tank 31, the second buffer tank 32, and the multi-stage filtration device, exiting from the storage tank 1... The return flow is returned to the storage tank 1, thereby realizing the circulation of photoresist; the first buffer tank 31 and the second buffer tank 32 are arranged in series to temporarily store photoresist and buffer the pulse pressure fluctuations of the low-pulse photoresist filtration circulation system; the top of the first buffer tank 31 is connected to a first air passage to supply compressed air into the first buffer tank 31, using the constant pressure of the compressed air to eliminate pulse pressure fluctuations; the top of the second buffer tank 32 is connected to a second air passage to supply compressed air into the second buffer tank 32, using the constant pressure of the compressed air to eliminate pulse pressure fluctuations; the multi-stage filtration device is used for filtration of photoresist to remove particulate matter in the photoresist.

[0076] In use, the photoresist in the storage tank 1 is pumped into the first buffer tank 31 by the circulation pump 2; compressed air is supplied to the first buffer tank 31 from the first air passage, forcing the photoresist in the first buffer tank 31 to flow into the second buffer tank 32; compressed air is supplied to the second buffer tank 32 from the second air passage, forcing the photoresist in the second buffer tank 32 to flow into the multi-stage filtration device; after being filtered by the multi-stage filtration device, the photoresist flows back into the storage tank 1.

[0077] This application increases the buffer volume by arranging two buffer tanks in series on the front side of the inlet of the multi-stage filtration device. This effectively absorbs high-frequency pulse pressure fluctuations, greatly reduces the peak value and frequency of pulse pressure fluctuations, avoids pulse pressure disturbances to the multi-stage filtration device, improves the filtration effect, reduces the number of particles in the photoresist, and ensures the purity and quality of the photoresist. The system has a simple structure and low cost.

[0078] Based on the above technical solution, and further preferably, the storage tank 1 is provided with a stirring paddle 11 for stirring the photoresist in the storage tank 1, ensuring that the various components in the photoresist are fully mixed and evenly distributed, which is suitable for high viscosity photoresist and avoids excessive local concentration of high viscosity photoresist, which affects the quality; the top of the storage tank 1 is provided with a first pneumatic motor 12, and the output shaft of the first pneumatic motor 12 is connected to the upper end of the stirring paddle 11 for driving the stirring paddle 11 to rotate.

[0079] More preferably, the air inlet of the first pneumatic motor 12 is connected to one end of the first compressed air circuit, and the other end of the first compressed air circuit is connected to a compressed air source for supplying compressed air from the first compressed air circuit to the first pneumatic motor 12. The compressed air in the first pneumatic motor 12 is discharged from the exhaust port of the first pneumatic motor 12, thereby driving the first pneumatic motor 12 to rotate.

[0080] In this embodiment, a first pressure gauge 121 and a first pressure regulating valve 122 are provided in the first compressed air circuit. The first pressure gauge 121 is used to detect the gas pressure flowing from the first compressed air circuit to the first pneumatic motor 12. The first pressure regulating valve 122 is used to regulate the flow rate and on / off state of the compressed air in the first compressed air circuit, thereby regulating the rotational speed and on / off state of the first pneumatic motor 12, and thus regulating the stirring rate of the stirring paddle 11. In use, the first pressure regulating valve 122 can more accurately regulate the stirring rate of the stirring paddle 11 based on the gas pressure detected by the first pressure gauge 121.

[0081] Furthermore, the top of the liquid storage tank 1 is also provided with a ventilation valve 13 (i.e. a breather valve) to regulate the air pressure inside the liquid storage tank 1, maintain the air pressure balance inside and outside the liquid storage tank 1, prevent the liquid storage tank 1 from being damaged due to overpressure or negative pressure, and at the same time reduce the loss of photoresist volatilization and environmental pollution.

[0082] In this embodiment, the outlet of the storage tank 1 is connected to the inlet of the circulation pump 2 through a first pipeline, so that the photoresist discharged from the outlet of the storage tank 1 can flow to the circulation pump 2; a switch valve 14 is provided on the first pipeline to control the on / off state of the photoresist in the first pipeline.

[0083] More preferably, a sampling valve 15 is also provided on the first pipeline for sampling the photoresist in the first pipeline; in use, the sampling valve 15 is opened to extract a portion of the photoresist sample from the first pipeline and to test the purity and quality of the photoresist.

[0084] In this embodiment, the circulating pump 2 is a pneumatic diaphragm pump. The pneumatic motor of the circulating pump 2 is connected to one end of the second compressed air circuit, and the other end of the second compressed air circuit is connected to a compressed air source. It is used to supply compressed air from the second compressed air circuit to the pneumatic motor of the circulating pump 2. The compressed air in the pneumatic motor is discharged from the exhaust port of the pneumatic motor, thereby driving the circulating pump 2 through the pneumatic motor.

[0085] Furthermore, a second pressure regulating valve 201 is provided in the second compressed air circuit to regulate the flow rate and on / off state of the compressed air in the second compressed air circuit, thereby regulating the speed and on / off state of the pneumatic motor of the circulating pump 2, and further regulating the circulation flow rate of the circulating pump 2, and controlling the working efficiency and on / off state of the circulating pump 2.

[0086] More preferably, the outlet of the first buffer tank 31 is connected to the inlet of the second buffer tank 32 through a damping tube 33, which is used for the photoresist in the first buffer tank 31 to flow into the second buffer tank 32. During the flow of the photoresist, vibration is reduced. When the photoresist flows through the damping tube 33, it rubs against the damping tube 33 and converts kinetic energy into heat energy, consuming the energy of the pulse pressure fluctuation. At the same time, the damping tube 33 slows down the transmission speed of the pulse pressure fluctuation.

[0087] Furthermore, the damping tube 33 has a tapered structure, with its inner diameter gradually decreasing from the outlet of the first buffer tank 31 to the inlet of the second buffer tank 32. This increases the flow rate of the photoresist within the damping tube 33, thereby consuming the energy of pulse pressure fluctuations. In this embodiment, the tapering angle of the damping tube 33 is 15°.

[0088] More preferably, the inner wall of the damping tube 33 is provided with a spiral guide groove 331, which allows the photoresist to flow along the spiral guide groove 331 within the damping tube 33. This extends the flow path of the photoresist within the damping tube 33, increases the friction between the photoresist and the damping tube 33, converts kinetic energy into heat energy, and consumes the energy of the pulse pressure fluctuation. In this embodiment, the depth of the guide groove 331 is one-tenth of the inner diameter of the damping tube 33.

[0089] Furthermore, the low-pulse photoresist filtration circulation system also includes a third compressed air path. One end of the third compressed air path is connected to a compressed air source, and the other end is connected to the first air path and the second air path via a three-way valve. This third compressed air path supplies compressed air to the first buffer tank 31 and the second buffer tank 32 via the first and second air paths, respectively. A third pressure gauge 301 and a third pressure regulating valve 302 are installed on the third compressed air path. The third pressure gauge 301 detects the gas pressure flowing from the third compressed air path to the first buffer tank 31 and the second buffer tank 32. The third pressure regulating valve 302 regulates the flow rate and on / off state of the compressed air in the third compressed air path, thereby regulating the gas pressure flowing from the third compressed air path to the first buffer tank 31 and the second buffer tank 32. In use, the third pressure regulating valve 302 can more accurately regulate the gas pressure based on the gas pressure detected by the third pressure gauge 301.

[0090] More preferably, the three-way valve is provided with a flow-dividing regulating valve 303 for regulating and distributing the flow rate of compressed gas flowing from the third compressed gas path into the first gas path and the second gas path.

[0091] Furthermore, a pressure balancing valve is provided at the top of the first buffer tank 31 to adjust the gas pressure inside the first buffer tank 31, control the pressure difference between the gas pressure at the top of the first buffer tank 31 and the circulation pump 2, and ensure that the photoresist inside the first buffer tank 31 flows to the second buffer tank 32.

[0092] In this embodiment, an exhaust valve 311 is connected to the top of the first buffer tank 31 for venting gas from the first buffer tank 31. During maintenance, the exhaust valve 311 is used to release gas and relieve pressure.

[0093] Furthermore, the multi-stage filtration device includes a first filter 41 and a second filter 42, wherein the first filter 41 and the second filter 42 are arranged in series.

[0094] More preferably, the first filter 41 is provided with a first filter element for coarse filtration of the photoresist, removing larger and moderately sized particles from the photoresist; the second filter 42 is provided with a second filter element, the pore size of which is smaller than that of the first filter element, for fine filtration of the photoresist, removing smaller and finer particles from the photoresist; the multi-stage filtration device gradually increases the filtration precision from the first filter 41 to the second filter 42, greatly improving filtration efficiency and effect, reducing the probability of clogging, extending service life, and reducing replacement frequency.

[0095] In this embodiment, the pore size of the second filter element is 0.1 μm, and the pore size of the first filter element is slightly larger than 0.1 μm. Under optimal conditions, after filtration, the number of particles with a diameter greater than 0.1 μm in each milliliter of photoresist can be reduced to less than 50, which can meet the requirements for nanoscale filtration of photoresist.

[0096] More preferably, the outlet of the multi-stage filtration device is connected to the top return port of the storage tank 1 via a return pipeline, so that the filtered photoresist can flow back into the storage tank 1 from the return pipeline; a filling port 43 is provided on the return pipeline, so that the photoresist can be discharged from the filling port 43; a shut-off valve is provided on the filling port 43, so as to adjust the opening and closing of the filling port 43. After the photoresist sample is tested and the quality and purity meet the standards, the shut-off valve is opened, and the photoresist is filled into the storage tank from the filling port 43;

[0097] In this embodiment, the low-pulse photoresist filtration and circulation system further includes a balance for weighing the photoresist in the storage container.

[0098] Furthermore, the low-pulse photoresist filtration circulation system also includes a fan filter unit (FFU) for filtering the filling space during photoresist filling to ensure the cleanliness of the filling space.

[0099] This invention increases the buffer volume by arranging two buffer tanks in series on the front side of the inlet of the multi-stage filtration device. This effectively absorbs high-frequency pulse pressure fluctuations. Compared with the existing technology that only sets a single buffer tank, the series connection of two buffer tanks can usually reduce the peak pulse pressure by 60% to 70% and reduce the pulse pressure fluctuation frequency to one-third of the original pulse pressure fluctuation frequency. This effectively avoids pulse pressure disturbance to the multi-stage filtration device, improves the filtration effect, reduces the number of particles in the photoresist, and ensures the purity and quality of the photoresist. The system has a simple structure and low cost. Example

[0100] This embodiment is basically the same as embodiment 1, except that:

[0101] like Figure 3As shown in this embodiment, a low-pulse photoresist filtration and circulation system is provided. A level sensor 35 is installed on the outside of both the first buffer tank 31 and the second buffer tank 32 to measure the photoresist level within either tank. The level sensor 35 has a low level line 351 and a high level line 352. When the photoresist level in the first buffer tank 31 and / or the second buffer tank 32 is lower than the low level line 351 or higher than the high level line 352, the pressure regulating device adjusts the air pressure within the first buffer tank 31 and / or the second buffer tank 32, thereby maintaining the photoresist level within the first buffer tank 31 and the second buffer tank 32 within a stable range. The first buffer tank 31 focuses on pressure buffering, while the second buffer tank 32 focuses on flow rate stability. Example

[0102] This embodiment is basically the same as embodiment 1, except that:

[0103] like Figure 4 As shown, this embodiment provides a low-pulse photoresist filtration circulation system. A first flow regulating valve 313 and a first pressure sensor 312 are provided in the first gas path. The first flow regulating valve 313 is used to regulate the flow rate and on / off state of the first gas path. The first pressure sensor 312 is connected to the top of the first buffer tank 31 and is used to detect the gas pressure at the top of the first buffer tank 31, control the first flow regulating valve 313 to regulate the flow rate of the first gas path, thereby regulating the gas pressure at the top of the first buffer tank 31.

[0104] More preferably, a second flow regulating valve 322 and a second pressure sensor 321 are provided in the second gas path; the second flow regulating valve 322 is used to regulate the flow rate and on / off state of the second gas path; the second pressure sensor 321 is connected to the top of the second buffer tank 32 and is used to detect the gas pressure at the top of the second buffer tank 32, control the second flow regulating valve 322 to regulate the flow rate of the second gas path, thereby regulating the gas pressure at the top of the second buffer tank 32.

[0105] During use, the first pressure sensor 312 and the second pressure sensor 321 control the first flow regulating valve 313 and the second flow regulating valve 322 respectively to regulate the top gas pressure of the first buffer tank 31 and the second buffer tank 32, thereby realizing the linkage control and adjustment of the top gas pressure of the first buffer tank 31 and the second buffer tank 32, ensuring that the photoresist flows from the first buffer tank 31 to the second buffer tank 32.

[0106] Furthermore, a one-way valve 34 is connected between the second buffer tank 32 and the damping tube 33, for the photoresist in the first buffer tank 31 to flow unidirectionally from the damping tube 33 to the second buffer tank 32, preventing the photoresist in the second buffer tank 32 from flowing back.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A low-pulse photoresist filtration and circulation system, characterized in that, include: Storage tank, circulating pump, first buffer tank, second buffer tank, and multi-stage filtration device; The circulating pump, the first buffer tank, the second buffer tank, and the multi-stage filtration device are connected in sequence through pipelines between the bottom outlet of the storage tank and the top return outlet of the storage tank. The circulation pump is used to pump the photoresist discharged from the outlet of the storage tank into the first buffer tank. The first buffer tank and the second buffer tank are connected in series to temporarily store photoresist and buffer the pulse pressure fluctuations of the low-pulse photoresist filtration circulation system. The top of the first buffer tank is connected to a first air passage for supplying compressed air into the first buffer tank; The top of the second buffer tank is connected to a second air passage for supplying compressed air into the second buffer tank; The multi-stage filtration device is used for filtering photoresist.

2. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The storage tank is equipped with a stirring paddle for stirring the photoresist inside the storage tank. A first pneumatic motor is installed on the top of the liquid storage tank. The output shaft of the first pneumatic motor is connected to the upper end of the stirring paddle to drive the stirring paddle to rotate.

3. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The top of the liquid storage tank is also equipped with a venting valve for regulating the air pressure inside the liquid storage tank.

4. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The circulating pump is a pneumatic diaphragm pump. The pneumatic motor of the circulating pump is connected to one end of the second compressed air circuit, and the other end of the second compressed air circuit is connected to a compressed air source. It is used to supply compressed air from the second compressed air circuit to the pneumatic motor of the circulating pump, and drive the circulating pump through the pneumatic motor.

5. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The outlet of the first buffer tank is connected to the inlet of the second buffer tank through a damping tube, which is used to reduce vibration during the flow of photoresist from the first buffer tank to the second buffer tank.

6. The low-pulse photoresist filtering circulation system according to claim 5, characterized in that, The damping tube has a tapered structure; The inner wall of the damping tube is provided with a spiral guide groove for the photoresist to flow along the spiral guide groove inside the damping tube.

7. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The low-pulse photoresist filtration circulation system also includes a third compressed air path. One end of the third compressed air path is connected to a compressed air source, and the other end is connected to the first air path and the second air path through a three-way valve, respectively, for supplying compressed air from the third compressed air path to the first buffer tank and the second buffer tank through the first air path and the second air path, respectively. The third compressed air circuit is equipped with a third pressure gauge and a third pressure regulating valve. The third pressure gauge is used to detect the gas pressure flowing from the third compressed gas path to the first buffer tank and the second buffer tank; The third pressure regulating valve is used to regulate the flow rate and on / off state of compressed air in the third compressed air circuit.

8. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The first gas line is equipped with a first flow regulating valve and a first pressure sensor; The first flow regulating valve is used to regulate the flow rate and on / off state of the first air passage; The first pressure sensor is connected to the top of the first buffer tank and is used to detect the gas pressure at the top of the first buffer tank and control the first flow regulating valve to regulate the flow rate of the first gas path. The second air path is equipped with a second flow regulating valve and a second pressure sensor; The second flow regulating valve is used to regulate the flow rate and on / off state of the second air passage; The second pressure sensor is connected to the top of the second buffer tank and is used to detect the gas pressure at the top of the second buffer tank and control the second flow regulating valve to regulate the flow rate of the second gas path.

9. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The multi-stage filtration device includes: a first filter and a second filter, wherein the first filter and the second filter are arranged in series. The first filter contains a first filter element for coarse filtration of the photoresist; The second filter contains a second filter element, the pore size of which is smaller than that of the first filter element, for fine filtration of the photoresist.

10. The low-pulse photoresist filtering circulation system according to claim 1, characterized in that, The outlet of the multi-stage filtration device is connected to the top return port of the storage tank via a return pipeline, so that the filtered photoresist can flow back into the storage tank from the return pipeline. The return pipeline is provided with a filling port for the photoresist to be discharged from the filling port of the return pipeline.

Images