Spent liquor recovery system and method

Abstract

The present disclosure provides a waste liquid recovery system and method, belonging to the technical field of semiconductor manufacturing. The waste liquid recovery system comprises: a waste liquid recovery device for collecting waste liquid discharged by a developing machine; a waste liquid filtering device for filtering the waste liquid collected by the waste liquid recovery device, filtering out chemical substances generated after the developing liquid reacts with the photoresist, and discharging the remaining developing liquid and water that have not reacted to a concentration adjusting device; the concentration adjusting device is used for monitoring the concentration of a solution formed by mixing the developing liquid and water discharged by the waste liquid filtering device; when the concentration of the solution meets the condition, the solution is discharged; when the concentration of the solution does not meet the condition, the concentration of the solution is adjusted by controlling the content of water in the solution, so that the concentration of the solution meets the condition, and the solution is discharged when the concentration of the solution meets the condition.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor manufacturing, and particularly relates to a waste liquid recovery system and method. BACKGROUND

[0002] Photoetching is an important step in semiconductor manufacturing, and developing solution is the main chemical solution used in photoetching process. The main component of developing solution is tetramethylammonium hydroxide (TMAH). In the photoetching process, TMAH reacts with photosensitizer in the photoresist in a single wafer developing machine to produce reaction compounds and water.

[0003] A new developing solution is used for each wafer in the single wafer developing machine, and the used developing solution is immediately discharged into the waste liquid recovery system, so that the developing effect is stable. However, this photoetching method has the problem of large developing solution consumption. SUMMARY

[0004] The embodiments of the present disclosure provide a waste liquid recovery system and method, which can recover the unreacted developing solution in the waste liquid, thereby reducing the consumption of developing solution and saving cost. The technical solution is as follows:

[0005] The embodiments of the present disclosure provide a waste liquid recovery system, which comprises a waste liquid recovery device, a waste liquid filtering device and a concentration adjusting device.

[0006] The waste liquid recovery device is used for collecting waste liquid discharged from a developing machine.

[0007] The waste liquid filtering device is used for filtering the waste liquid collected by the waste liquid recovery device, filtering out chemical substances produced after the developing solution reacts with the photoresist, and discharging the remaining unreacted developing solution and water to the concentration adjusting device.

[0008] The concentration adjusting device is used for monitoring the concentration of a solution formed by mixing the developing solution and water discharged from the waste liquid filtering device. When the concentration of the solution meets the condition, the solution is discharged. When the concentration of the solution does not meet the condition, the concentration of the solution is adjusted by controlling the content of water in the solution, so that the concentration of the solution meets the condition, and the solution is discharged when the concentration of the solution meets the condition.

[0009] The solution discharged from the waste liquid filtering device comprises the remaining unreacted developing solution and water produced by the reaction.

[0010] Optionally, the waste liquid filtering device comprises a cylindrical main body, the top of the cylindrical main body has an opening, and the bottom of the cylindrical main body has an outlet.

[0011] The waste liquid filtering device further comprises a first filter screen and a second filter screen, the first filter screen is connected with the opening of the cylindrical body, and the second filter screen is connected with the inner wall of the cylindrical body, and the second filter screen is located between the first filter screen and the outlet.

[0012] The mesh of the second filter screen is smaller than that of the first filter screen.

[0013] Optionally, the first filter screen is a micron-level filter screen, and the second filter screen is a nanometer-level filter screen.

[0014] Optionally, the concentration adjusting device comprises a main body structure, and a containing cavity is formed in the middle of the main body structure.

[0015] The opening of the containing cavity is a solution inlet, the side wall of the main body structure is provided with a solution discharge outlet and a waste water discharge outlet which are in communication with the containing cavity, and the height of the solution discharge outlet is greater than that of the waste water discharge outlet.

[0016] The adjusting device further comprises a concentration detection unit located in the containing cavity, and a third filter screen and an electromagnetic valve located at the waste water discharge outlet, and the concentration detection unit and the electromagnetic valve are electrically connected.

[0017] Optionally, the concentration detection unit is an ultrasonic concentration detection unit, and the ultrasonic concentration detection unit is located on the side wall of the containing cavity and around the solution discharge outlet.

[0018] Optionally, the adjusting device further comprises a rotating stirring mechanism located in the containing cavity.

[0019] Optionally, the rotating stirring mechanism comprises a motor and a rotating structure, and the output shaft of the motor is inserted into the center hole of the rotating structure.

[0020] Optionally, the rotating structure comprises a cylindrical body and a plurality of spaced slits on the outer side wall of the cylindrical body.

[0021] Optionally, the gap between the outer side wall of the cylindrical body and the side wall of the containing cavity is 5-15 cm.

[0022] The embodiment of the present disclosure provides a waste liquid recycling method, which comprises the following steps:

[0023] Collecting waste liquid discharged from a developing machine;

[0024] Filtering the collected waste liquid to remove chemical substances generated after the developing solution reacts with the photoresist, and discharging the remaining developing solution and water which have not reacted;

[0025] Monitoring the concentration of the solution formed by mixing the discharged developing solution and water.

[0026] When the concentration of the solution meets the condition, the solution is discharged; when the concentration of the solution does not meet the condition, the concentration of the solution is adjusted by controlling the content of water in the solution, so that the concentration of the solution meets the condition, and when the concentration of the solution meets the condition, the solution is discharged.

[0027] The technical scheme provided by the embodiments of the present disclosure has the following beneficial effects:

[0028] In the technical scheme provided by the embodiments of the present disclosure, the waste liquid discharged by the developing machine is first collected by the waste liquid recovery device; then the chemical substances generated by the reaction in the waste liquid are filtered by the waste liquid filtering device, and the unreacted developing liquid and water are obtained by filtering; since the concentration of the developing liquid has requirements for photolithography, the solution of the filtered developing liquid and water needs to be monitored for concentration, and when the concentration meets the condition, the solution is provided to the developing machine of photolithography again, and if the concentration of the solution does not meet the condition, the concentration needs to be adjusted by controlling the content of water in the solution until the concentration meets the condition, and then the solution is provided to the developing machine of photolithography again. The scheme filters and adjusts the concentration of the waste liquid to obtain the developing liquid suitable for photolithography, avoids the waste of the unreacted developing liquid in the waste liquid, and thus reduces the consumption of the developing liquid and saves costs. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical scheme in the embodiments of the present disclosure, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without creative labor.

[0030] Figure 1 is a structural schematic diagram of a waste liquid recovery system provided by an embodiment of the present disclosure;

[0031] Figure 2 is a structural schematic diagram of a waste liquid filtering device provided by an embodiment of the present disclosure;

[0032] Figure 3 is a structural schematic diagram of a concentration adjusting device provided by an embodiment of the present disclosure;

[0033] Figure 4 is a structural schematic diagram of a control circuit provided by an embodiment of the present disclosure;

[0034] Figure 5 is a structural schematic diagram of another control circuit provided by an embodiment of the present disclosure;

[0035] Figure 6 is a schematic diagram of a rotating structure provided by an embodiment of the present disclosure;

[0036] Figure 7 is a flow chart of a waste liquid recycling method provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0037] For the purposes of the present disclosure, technical solutions and advantages, the following will be further described in detail with reference to the drawings.

[0038] Unless otherwise defined, technical terms or scientific terms used herein should be understood as having the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms "first", "second", "third" and similar terms used in the specification and claims of the present patent application do not indicate any order, number or importance, but are only used to distinguish different components. Similarly, the terms "one" or "a" and the like do not indicate a quantity limitation, but indicate the presence of at least one. The terms "include" or "contain" and the like mean that the components or objects appearing before "include" or "contain" cover the components or objects listed after "include" or "contain" and their equivalents, and do not exclude other components or objects. The terms "connected" or "connected" and the like are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] The following formula is the reaction formula of the photoresist and the developer, and the reaction produces chemicals and water:

[0040]

[0041] Figure 1 is a structural schematic diagram of a waste liquid recycling system provided by an embodiment of the present disclosure. Referring to Figure 1 , the waste liquid recycling system comprises a waste liquid recycling device 101, a waste liquid filtering device 102 and a concentration adjusting device 103.

[0042] The waste liquid recycling device 101 is used to collect waste liquid discharged from a developing machine;

[0043] The waste liquid filtering device 102 is used to filter the waste liquid collected by the waste liquid recycling device, filter out the chemicals produced after the reaction of the developer and the photoresist, and discharge the remaining developer and water that have not reacted to the concentration adjusting device.

[0044] The concentration adjusting device 103 is used to monitor the concentration of the solution of the mixed developer and water discharged by the waste liquid filtering device; when the concentration of the solution meets the condition, the solution is discharged; when the concentration of the solution does not meet the condition, the concentration of the solution is adjusted by controlling the content of water in the solution, so that the concentration of the solution meets the condition, and the solution is discharged when the concentration of the solution meets the condition.

[0045] The concentration of the solution refers to the concentration of the developer in the solution.

[0046] In the technical scheme provided in the embodiments of the present disclosure, the waste liquid discharged by the developing machine is first collected by the waste liquid recovery device; then the chemical substances generated by the reaction are filtered by the waste liquid filtering device, and the unreacted developer and water are obtained by filtering; since the concentration of the developer has requirements for photolithography, the concentration of the solution of the filtered developer and water needs to be monitored, and the solution is provided to the developing machine of photolithography again when the concentration meets the condition; if the concentration of the solution does not meet the condition, the concentration needs to be adjusted by controlling the content of water in the solution until the concentration meets the condition, and then the solution is provided to the developing machine of photolithography again. The scheme obtains the developer suitable for photolithography by filtering and adjusting the concentration of the waste liquid, avoids the waste of the unreacted developer in the waste liquid, thereby reducing the consumption of the developer and saving the cost.

[0047] The waste liquid recovery device 101 is a tank or a cylindrical structure, as long as it can meet the collection of the waste liquid.

[0048] Referring to Figure 1 , the waste liquid recovery device 101 collects the waste liquid discharged by the reaction unit of the developing machine. After the waste liquid is processed by the waste liquid recovery system provided in the present disclosure, the unreacted developer is output to the developer temporary storage tank, and then is re-input to the reaction unit for use, thereby forming a cycle. Of course, the developer temporary storage tank is used to store the newly added developer in addition to the developer recovered by the present disclosure.

[0049] In a possible implementation manner of the present disclosure, the waste liquid in the waste liquid recovery device 101 is pumped (for example, a gas pump) to the waste liquid filtering device 102.

[0050] In another possible implementation manner of the present disclosure, the outlet of the waste liquid recovery device 101 can also be directly communicated with the inlet of the waste liquid filtering device 102, so that the waste liquid in the waste liquid recovery device 101 can flow directly to the waste liquid filtering device 102.

[0051] Figure 2 is a structural schematic view of a waste liquid filtering device provided in the embodiments of the present disclosure. Referring to Figure 2 (a) and Figure 2(b), the waste liquid filtering device comprises a cylindrical body 121, the top of the cylindrical body 121 is provided with an opening 122, and the bottom of the cylindrical body 121 is provided with an outlet 123.

[0052] The waste liquid filtering device further comprises a first filter screen 124 and a second filter screen 125, the first filter screen 124 is connected with the opening 122 of the cylindrical body 121, and the second filter screen 125 is connected with the inner wall of the cylindrical body 121 and located between the first filter screen 124 and the outlet 123.

[0053] The mesh of the second filter screen 125 is smaller than that of the first filter screen 124.

[0054] In the implementation, the first filter screen is arranged at the opening of the cylindrical body, and the second filter screen is arranged at the middle part of the cylindrical body, so that the waste liquid can pass through the first filter screen and the second filter screen in sequence, and the waste liquid is filtered through the two layers of filter screens, thereby ensuring that impurities and chemical substances generated in the reaction are filtered out.

[0055] The first filter screen is a micron filter screen, and the second filter screen is a nanometer filter screen. The micron filter screen is used to filter out impurities in the waste liquid, and the nanometer filter screen is used to filter out chemical substances generated in the photoetching process. Through the above two steps of filtering, the chemical substances generated after the development liquid reacts with the photoresist are filtered out, and the remaining development liquid and water are effectively discharged to the concentration adjusting device.

[0056] Since the molecules of water and the development liquid are smaller than the chemical substances generated in the reaction, the appropriate nanometer filter screen can be selected to filter the reaction substances while allowing water and the development liquid to pass through.

[0057] In the embodiment of the present disclosure, the first filter screen and the second filter screen are detachably connected to the cylindrical body 121, so that the filter screens can be conveniently replaced.

[0058] As shown in Figure 2 (a) and Figure 2 (b), the cavity of the cylindrical body 121 is composed of two parts, the upper cavity is in the shape of a circular truncated cone, and the lower cavity is in the shape of a circular cylinder.

[0059] Figure 2 (c) is Figure 2 (b), the cross-sectional view of B-B in (b) is shown in Figure 2 (b) and Figure 2 (c), the outlet 123 is in communication with the lower cavity, and the outlet 123 is arranged on the side wall of the cylindrical body 121.

[0060] In other implementations, the outlet 123 can also be formed at the bottom of the cylindrical body 121, and the present disclosure does not limit thereto.

[0061] Figure 3 is a structural schematic diagram of a concentration adjusting device provided by an embodiment of the present disclosure. Referring to Figure 3 (a), the concentration adjusting device comprises a body structure 131, and a containing cavity 132 is formed in the middle of the body structure 131.

[0062] Figure 3 (b) is Figure 3 (a) is a sectional view along the direction of A-A in (a). Figure 3 (c) is Figure 3 (a) is a side view of the body structure 131. Referring to Figure 3 (b) and (c), the opening of the containing cavity 132 is a solution inlet, the side wall of the body structure 131 has a solution outlet 133 and a waste water outlet 134 which communicate with the containing cavity 132, and the height of the solution outlet 133 is greater than that of the waste water outlet 134.

[0063] The adjusting device further comprises a concentration detection unit 135 located in the containing cavity 132 and a third filter screen (not shown) and a solenoid valve (not shown) located at the waste water outlet 134, and the concentration detection unit 135 and the solenoid valve are electrically connected.

[0064] In this implementation, the concentration of the solution in the containing cavity 132 is detected by the concentration detection unit 135, and if the concentration is low, it means that the amount of water is too high, and then the solenoid valve is controlled to be turned on to drain water from the waste water outlet 134. Since the third filter screen exists, the developing solution will not be drained. If the concentration meets the condition, there is no need to drain water. When the concentration meets the condition, the developing solution is drained through the solution outlet 133.

[0065] Since a large amount of water is generated in the photolithography process, generally, the concentration of the solution is too low and the amount of water is too high, and the water needs to be drained. Generally, the concentration of the solution is not too high.

[0066] In a possible implementation of the present disclosure, the solenoid valve 137 can be controlled by a circuit structure.

[0067] Figure 4 is a structural schematic diagram of a control circuit provided by an embodiment of the present disclosure. As Figure 4 shown, the output end of the concentration detection unit 135 and one input end of a comparison circuit 136 are connected, another input end of the comparison circuit 136 inputs a signal representing a concentration threshold, and the output end of the comparison circuit 136 is connected to the solenoid valve 137.

[0068] The comparison circuit 136 outputs a control signal to the electromagnetic valve 137 according to the comparison result, to control the on-off of the electromagnetic valve. For example, when the concentration value output by the concentration detection unit 135 is greater than the concentration threshold value, the comparison circuit 136 outputs a low level to control the electromagnetic valve 137 to be closed; when the concentration value output by the concentration detection unit 135 is not greater than the concentration threshold value, the comparison circuit 136 outputs a high level to control the electromagnetic valve 137 to be turned on.

[0069] The concentration detection unit 135 periodically collects the concentration value, the comparison circuit 136 periodically performs comparison, and then periodically controls the on-off of the electromagnetic valve 137, so as to finally make the concentration value close to the concentration threshold value.

[0070] In another possible implementation manner of the present disclosure, the electromagnetic valve 137 can be controlled by a software algorithm.

[0071] Figure 5 is another structure diagram of a control circuit provided by an embodiment of the present disclosure. As shown in Figure 5 The output end of the concentration detection unit 135 is connected to the input end of the processor 138, and the control end of the processor 138 is connected to the electromagnetic valve 137.

[0072] The processor 138 determines whether drainage is needed according to the concentration value detected by the concentration detection unit 135. If the concentration meets the condition, drainage is not needed, and if the concentration does not meet the condition, drainage is needed. When drainage is needed, the processor 138 calculates the amount of water to be drained according to the concentration value and the capacity of the containing cavity, generates an electromagnetic valve control signal based on the amount of water to be drained, and controls the electromagnetic valve to drain the corresponding volume of water. During the drainage process, the concentration detection unit 135 can feed back the latest concentration value in real time until the concentration value meets the condition.

[0073] In a possible implementation manner of the present disclosure, the concentration detection unit 135 can be an ultrasonic concentration detection unit, that is, the concentration detection unit 135 is an ultrasonic concentration detection unit. The ultrasonic wave propagates at different speeds in solutions with different concentrations, and the concentration detection can be realized based on this principle.

[0074] In other possible implementation manners of the present disclosure, the concentration detection unit 135 can also be other types of concentration detection devices, which are not limited.

[0075] As shown in Figure 3 (b), the concentration detection unit 135 is located on the side wall of the containing cavity 132 and around the solution discharge port 133.

[0076] If the concentration detection unit 135 is placed at the bottom of the containing cavity, it cannot effectively monitor the overall concentration in the containing cavity, because the bottom concentration is usually high due to the precipitation of the developer, so the concentration detection unit 135 is placed near the solution discharge port 133, which is designed in the middle of the containing cavity, so that the concentration of the solution when it is discharged can be effectively and timely monitored.

[0077] Since the molecular weight of water is 18 and the molecular weight of tetramethyl ammonium hydroxide is 91.15, water molecules are smaller than tetramethyl ammonium hydroxide, so water can pass through the third filter screen, while the developer cannot pass through the filter screen, thereby achieving the purpose of controlling the concentration of the developer.

[0078] Referring again to Figure 3 (a), a plurality of mounting holes 139 are formed in the top surface of the main body structure 131, through which a cover plate can be mounted on the main body structure 131, and the cover plate is provided with an inlet for outputting the filtered developer and water from the waste liquid filtering device to the concentration adjusting device.

[0079] Since the solution concentration will be inaccurate due to the precipitation of the solution, affecting the accurate judgment of the solution concentration by the concentration detection unit 135, resulting in fluctuations in the solution concentration, a rotating stirring mechanism can be added in the containing cavity to rotate at a constant speed to avoid the precipitation of the solution and ensure more accurate detection of the solution concentration.

[0080] That is, the adjusting device further comprises a rotating stirring mechanism in the containing cavity.

[0081] Exemplarily, the rotating stirring mechanism comprises a motor and a rotating structure, and an output shaft of the motor is inserted into a central hole of the rotating structure.

[0082] Figure 6 is a schematic view of a rotating structure provided by an embodiment of the present disclosure. Figure 6 (a) is a side view of the rotating structure, Figure 6 (b) is Figure 6 (a) is a sectional view in the A-A direction. Referring to Figure 6 (a) and Figure 6 (b), the rotating structure comprises a cylindrical body 1310 and a plurality of spaced slits 1311 on the outer side wall of the cylindrical body 1310.

[0083] The middle part of the cylindrical body 1310 is a central hole 1312 connected to the output shaft of the motor. The rotating structure is driven by inserting the rotating shaft connected to the output shaft of the motor into the center of the rotating structure.

[0084] Among them, the slit 1311 is a slit-shaped groove, and the side of the slit 1311 away from the outer side wall is cylindrical, that is, wider than the width of the groove opening, so as to facilitate the flow of the solution in the slit.

[0085] In this implementation, the solution in the containing cavity is stirred evenly by slowly and uniformly stirring the developer in the containing cavity, thereby avoiding the problem of unstable solution concentration in the containing cavity. The multiple slits 1311 of the rotating structure have a spiral cross-section and are vertically slit-shaped, which can avoid the generation of bubbles in the containing cavity due to stirring.

[0086] In the embodiments of the present disclosure, the gap between the outer sidewall of the cylindrical body and the sidewall of the containing cavity is 5-15 cm.

[0087] For example, the gap between the outer sidewall of the cylindrical body and the sidewall of the containing cavity is 10 cm. The gap between the outer wall of the rotating structure and the inner wall of the containing cavity is 10 cm, thereby facilitating the flow of the solution in the cavity.

[0088] The above-described waste liquid recovery system provided by the present disclosure can be integrated with a developing machine, thereby achieving the recovery of the developer inside each developing machine.

[0089] Figure 7 is a flowchart of a waste liquid recovery method provided by an embodiment of the present disclosure. Referring to Figure 7 The waste liquid recovery method comprises the following steps.

[0090] 201: Collecting waste liquid discharged from a developing machine.

[0091] In a photolithography process, a chemical dispensing system (CDS) supplies developer to a temporary storage tank of a developing machine. A reaction unit of the developing machine uses the solution in the temporary storage tank to react with a product. After the reaction, waste liquid discharged from the developing machine is collected.

[0092] 202: Filtering the collected waste liquid to filter out chemical substances generated after the developer and photoresist react, and discharging the remaining developer and water that have not reacted.

[0093] In this step, the waste liquid can be filtered twice.

[0094] First, a first filter screen is used for first filtering, and then a second filter screen is used for second filtering.

[0095] The mesh size of the second filter screen is smaller than the mesh size of the first filter screen.

[0096] In this implementation, the waste liquid is filtered by two layers of filter screens, thereby ensuring that the reaction chemicals are filtered out.

[0097] The first filter screen is a micron-level filter screen, and the second filter screen is a nanometer-level filter screen. The micron-level filter screen filters out impurities in the waste liquid, and the nanometer-level filter screen filters out chemical substances generated in the photoetching process. Through the above two filtering steps, the chemical substances generated after the developer reacts with the photoresist are filtered out, and the remaining developer that has not reacted completely is effectively treated in the subsequent steps.

[0098] 203: Monitor the concentration of the solution formed by mixing the discharged developer and water.

[0099] When the concentration of the solution does not meet the condition, step 204 is performed; when the concentration of the solution meets the condition, step 205 is performed.

[0100] The concentration detection can be a concentration detection scheme based on ultrasonic technology. The ultrasonic wave propagates at different speeds in solutions with different concentrations, and the concentration detection can be realized based on this principle.

[0101] Since the concentration of the solution may not be accurate due to precipitation of the solution, the accurate judgment of the concentration of the solution is affected, and the concentration of the solution fluctuates. In order to ensure the accuracy of the concentration detection, the method further comprises the following steps during the concentration detection:

[0102] The solution formed by mixing the developer and water is uniformly rotated and stirred to prevent the solution from precipitating and to ensure that the detection of the concentration of the solution is more accurate.

[0103] 204: Adjust the concentration of the solution by controlling the water content in the solution, so that the concentration of the solution meets the condition.

[0104] Since a large amount of water is generated in the photoetching process, the concentration of the solution is usually too low, and the water content is too high, so drainage is required. The concentration of the solution is usually not too high.

[0105] In one possible implementation of the present disclosure, the size of the monitored concentration value and the concentration threshold value is compared; and then the on-off of the electromagnetic valve is controlled according to the concentration threshold value. When the electromagnetic valve is opened, water is discharged through the third filter screen, and the molecules of the developer are larger than water and cannot pass through the third filter screen.

[0106] For example, when the detected concentration value is greater than the concentration threshold value, a low level is output to control the electromagnetic valve to be closed, and when the detected concentration value is not greater than the concentration threshold value, a high level is output to control the electromagnetic valve to be turned on.

[0107] In addition, the concentration value is periodically collected, periodically compared, and then the on-off of the electromagnetic valve is periodically controlled, so that the concentration value and the concentration threshold value are finally similar.

[0108] In another possible implementation of the present disclosure, according to the detected concentration value, it is determined whether the water needs to be drained. If the concentration meets the condition, the water does not need to be drained, and if the concentration does not meet the condition, the water needs to be drained. When the water needs to be drained, the amount of water that needs to be drained is calculated according to the concentration value and the capacity of the containing cavity, an electromagnetic valve control signal is generated based on the amount of water that needs to be drained, and the electromagnetic valve is controlled to drain the corresponding volume of water. During the water draining process, the latest concentration value can be fed back in real time until the concentration value meets the condition.

[0109] 205: drain the solution.

[0110] The solution with the concentration meeting the condition is drained into a developer temporary storage tank for use in the reaction in the next photolithography process.

[0111] By repeatedly performing the above method steps, the effective substances in the residual reaction developer are recycled and purified to achieve the purpose of 100% utilization rate of the developer.

[0112] In the related art, the used developer is drained by a single developing machine, and the actual developer is drained without effective reaction. The scheme provided by the present disclosure is different from the traditional single developing machine, and the developer that does not react completely is recycled internally. Compared with the traditional way of entrusting a recycling agency to recycle, the present scheme has high recycling efficiency and low cost, and does not need additional costs such as transportation costs; the concentration control scheme is used to control the concentration, which can effectively control the reaction rate of the solution.

[0113] In addition, a rotary stirring mechanism is added in the solution concentration monitoring process, which effectively solves the inaccuracy of monitoring the solution concentration caused by the precipitation of effective components in the solution, and the problem of bubbles in the solution during stirring. When the solution monitoring and control are accurate, the recycling rate of the developer can reach 100%, and each recycling system is integrated in the developing machine to save space, and each developing machine can complete independent developer recycling. Moreover, the present scheme only drains solid chemical objects and does not involve the disposal of harmful chemical solutions, which greatly saves costs.

[0114] The above is not intended to limit the present disclosure in any form, although the present disclosure has been disclosed as above through examples, however, it is not intended to limit the present disclosure, any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical scheme of the present disclosure, and any simple modification, equivalent change and modification made to the above examples according to the technical essence of the present disclosure, all still belong to the scope of the technical scheme of the present disclosure.

Claims

1. A waste liquid recovery system, characterized in that, The waste liquid recovery system includes: a waste liquid recovery device, a waste liquid filtration device, and a concentration adjustment device; The waste liquid recovery device is used to collect the waste liquid discharged from the developing machine. The waste liquid filtration device is used to filter the waste liquid collected by the waste liquid recovery device, filter out the chemical substances generated after the developer reacts with the photoresist, and discharge the unreacted remaining developer and water to the concentration adjustment device. The concentration regulating device is used to monitor the concentration of the solution formed by the mixture of developer and water discharged from the waste liquid filtration device; when the concentration of the solution meets the conditions, the solution is discharged; when the concentration of the solution does not meet the conditions, the concentration of the solution is adjusted by controlling the water content in the solution to make the concentration of the solution meet the conditions, and the solution is discharged when the concentration of the solution meets the conditions. The concentration regulating device includes a main structure, and a receiving cavity is formed in the middle of the main structure; The opening of the receiving cavity is a solution inlet, and the side wall of the main structure has a solution outlet and a wastewater outlet communicating with the receiving cavity. The height of the solution outlet is greater than the height of the wastewater outlet. The regulating device also includes a concentration detection unit located in the containment cavity and a third filter screen and a solenoid valve located at the wastewater outlet, wherein the concentration detection unit and the solenoid valve are electrically connected.

2. The waste liquid recovery system according to claim 1, characterized in that, The waste liquid filtration device includes a cylindrical body with an opening at the top and an outlet at the bottom. The waste liquid filtration device further includes a first filter screen and a second filter screen. The first filter screen is connected to the opening of the cylindrical body, and the second filter screen is connected to the inner wall of the cylindrical body. The second filter screen is located between the first filter screen and the outlet. The mesh size of the second filter is smaller than that of the first filter.

3. The waste liquid recovery system according to claim 2, characterized in that, The first filter is a micron-sized filter, and the second filter is a nano-sized filter.

4. The waste liquid recovery system according to any one of claims 1 to 3, characterized in that, The concentration detection unit is an ultrasonic concentration detection unit, which is located on the side wall of the receiving cavity and around the solution outlet.

5. The waste liquid recovery system according to any one of claims 1 to 3, characterized in that, The regulating device also includes a rotary stirring mechanism located in the receiving cavity.

6. The waste liquid recovery system according to claim 5, characterized in that, The rotary stirring mechanism includes a motor and a rotating structure, with the output shaft of the motor inserted into the central hole of the rotating structure.

7. The waste liquid recovery system according to claim 6, characterized in that, The rotating structure includes a cylindrical body and a plurality of spaced slits located on the outer side wall of the cylindrical body.

8. The waste liquid recovery system according to claim 7, characterized in that, The gap between the outer wall of the cylindrical body and the side wall of the receiving cavity is 5~15cm.

9. A method for recycling waste liquid, characterized in that, The waste liquid recovery method is based on the waste liquid recovery system of claim 1, and the waste liquid recovery method includes: Collect the waste liquid discharged from the developing machine; The collected waste liquid is filtered to remove the chemical substances produced after the developer reacts with the photoresist, and the unreacted remaining developer and water are discharged. The concentration of the solution formed by mixing the discharged developer and water is monitored; When the concentration of the solution meets the conditions, the solution is discharged; when the concentration of the solution does not meet the conditions, the concentration of the solution is adjusted by controlling the water content in the solution to make the concentration of the solution meet the conditions, and when the concentration of the solution meets the conditions, the solution is discharged.

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