TMAH waste liquid recovery and continuous operation system in semiconductor industry

Abstract

The utility model provides a continuous operation system for recycling TMAH waste liquid in the semiconductor industry, which relates to the technical field of industrial wastewater treatment and comprises a primary purification subsystem and a deep purification subsystem which are connected in sequence, the primary purification subsystem comprises a first-stage filter, a second-stage filter and a third-stage filter which are connected in sequence; the deep purification subsystem comprises a raw material tank A and a raw material tank B, feed ports of the raw material tank A and the raw material tank B are connected with a discharge port of the preliminary purification subsystem, discharge ports of the raw material tank A and the raw material tank B are connected with an electrodialysis membrane stack, a TMAH purified liquid output port of the electrodialysis membrane stack is connected with the concentration adaptation subsystem, and a waste liquid output port of the electrodialysis membrane stack is connected with reflux ports of the raw material tank A and the raw material tank B and a TMAH waste liquid tank respectively; suspended photoresist is removed from the TMAH waste liquid through the primary purification subsystem, filtered liquid in the raw material tank A and the raw material tank B alternately enters an electrodialysis membrane stack for deep purification, and residual waste liquid is discharged. According to the utility model, zero discharge of hazardous waste in the TMAH waste liquid treatment process is realized, and photoresist can be completely recycled.

Description

A continuous operation system for TMAH waste liquid recovery in the semiconductor industry Technical Field

[0001] This utility model relates to the field of industrial wastewater treatment technology, and in particular to a system for continuous operation of TMAH waste liquid recovery in the semiconductor industry. Background Technology

[0002] In the semiconductor and optoelectronic fields, development is a crucial step in creating patterns in photoresist on silicon wafers. Soluble areas on the photoresist are dissolved by a chemical developer, leaving visible islands or window patterns on the silicon wafer surface. During development, the photoresist in non-exposed areas remains because it did not undergo a chemical reaction during exposure; the exposed photoresist gradually dissolves. The developer typically uses tetramethylammonium hydroxide (TMAH). Besides TMAH, waste developer also contains impurities such as photoresist. Waste developer is classified as hazardous waste, and the product itself is very expensive. Therefore, recycling TMAH from waste developer can reduce hazardous waste emissions and significantly lower production costs.

[0003] Currently, electrodialysis is the most commonly used process for TMAH recovery. However, during the recycling process, the photoresist in the feed solution can clog the electrodialysis unit. Furthermore, as TMAH is recovered from the feed solution, the pH in the feed solution chamber will decrease. At this point, a lot of originally dissolved photoresist will precipitate out of the feed solution. The suspended photoresist will not only clog the electrodialysis channels, but also adhere to the surfaces of the cathodic and cation membranes of the electrodialysis unit together with the newly precipitated photoresist, hindering ion migration and causing electrodialysis failure. Therefore, after a period of operation, the electrodialysis unit needs to be cleaned, which not only prevents the system from operating continuously, but also generates a lot of cleaning waste liquid, thus forming a lot of hazardous waste.

[0004] Currently, some filtration devices are installed before electrodialysis (application number 202221142996.6 discloses a waste developer regeneration system). By installing filtration devices before the electrodialysis device, the filtration methods include microfiltration, ultrafiltration, nanofiltration, or one or more coupled methods. Although the influence of photoresist on electrodialysis is considered, firstly, TMAH molecules cannot penetrate the nanofiltration membrane; only microfiltration and ultrafiltration can separate suspended photoresist and TMAH, and cleaning wastewater is generated. Secondly, it cannot solve the problem of dissolved photoresist clogging the electrodialysis membrane due to the decrease in pH during TMAH recovery. Considering electrodialysis membrane maintenance (application number 202210518520.6 discloses a waste developer regeneration device, regeneration method, and readable storage medium), the third embodiment mentions membrane cleaning. Although it can temporarily solve the problem of photoresist clogging, firstly, the cleaning frequency is very high, making the operation cumbersome; secondly, it generates a large amount of cleaning wastewater, and the system discharges hazardous waste; thirdly, cleaning may introduce new impurities, affecting product purity.

[0005] When any of the above situations occur, the continuous operation of the recycling system cannot be guaranteed, and the photoresist will enter the cleaning waste liquid, forming a large amount of hazardous waste, making photoresist recycling impossible. Therefore, it is urgent to solve the problem of photoresist contaminating the electrodialysis membrane in the electrodialysis feed solution, forming hazardous waste, and making photoresist recycling impossible. Summary of the Invention

[0006] In view of the technical problems existing in the background technology, this utility model patent provides a continuously operating system for recycling TMAH waste liquid in the semiconductor industry. It removes the suspended photoresist in the TMAH waste liquid and avoids the clogging of the electrodialysis membrane by dissolved photoresist, achieving zero discharge of hazardous waste and completely recycling the photoresist. It has very high economic recycling value and ecological value.

[0007] To achieve the above objectives, the technical solution of this utility model is as follows:

[0008] A continuously operating system for recycling TMAH waste liquid in the semiconductor industry includes a preliminary purification subsystem and a deep purification subsystem connected in sequence.

[0009] The preliminary purification subsystem includes a primary filter, a secondary filter, and a tertiary filter connected in sequence.

[0010] The deep purification subsystem includes raw material tank A and raw material tank B. The inlets of raw material tank A and raw material tank B are both connected to the outlet of the preliminary purification subsystem. The outlets of both are connected to the electrodialysis membrane stack. The TMAH purified liquid outlet of the electrodialysis membrane stack is connected to the concentration matching subsystem. The waste liquid outlet is connected to the reflux outlet of raw material tank A and raw material tank B and the TMAH waste liquid tank, respectively.

[0011] The TMAH waste liquid is filtered through the primary, secondary, and tertiary filters of the preliminary purification subsystem to remove suspended photoresist. The filtered liquid then enters the raw material tanks A and B of the deep purification subsystem. The filtered liquids from raw material tanks A and B are alternately fed into the electrodialysis membrane stack for deep purification. The deeply purified TMAH solution is sent to the concentration matching subsystem, and the remaining waste liquid is discharged.

[0012] As a further improvement of this utility model, it also includes a waste liquid feeding subsystem connected to the front end of the preliminary purification subsystem;

[0013] The waste liquid feeding subsystem includes a waste liquid feeding tank and a waste liquid feeding pump. The waste liquid feeding tank is equipped with a waste liquid feeding tank level gauge, and the outlet of the waste liquid feeding tank is connected to the suction port of the waste liquid feeding pump.

[0014] As a further improvement of this utility model, a waste liquid feed flow meter and a waste liquid feed pressure meter are provided on the pipeline between the waste liquid feed pump and the preliminary purification subsystem.

[0015] As a further improvement of this utility model, the primary filter, secondary filter and tertiary filter are all equipped with PP cotton pleated filter elements, with filtration accuracies of 50μm, 30μm and 5μm respectively.

[0016] As a further improvement of this utility model, the outlets of the raw material tank A and the raw material tank B are respectively connected to the security filter A and the security filter B, and the outlets of the security filter A and the security filter B are connected to the electrodialysis membrane stack.

[0017] As a further improvement of this utility model, the waste liquid outlet of the electrodialysis membrane stack is equipped with a conductivity meter.

[0018] When the conductivity of the remaining waste liquid passing through the waste liquid outlet is less than a preset first threshold, the remaining waste liquid is discharged into the TMAH waste liquid tank.

[0019] When the conductivity of the remaining waste liquid passing through the waste liquid outlet is greater than or equal to a preset first threshold, the remaining waste liquid is returned to the raw material tank A or raw material tank B via the return port to the corresponding raw material tank.

[0020] As a further improvement of this utility model, the TMAH purification solution outlet of the electrodialysis membrane stack is equipped with a concentrated water conductivity meter.

[0021] When the conductivity of the TMAH purified liquid at the TMAH purified liquid outlet is greater than or equal to a preset second threshold, the TMAH purified liquid is delivered to the concentration matching subsystem.

[0022] As a further improvement of this utility model, the TMAH purified liquid output port of the electrodialysis membrane stack is connected to the inlet of the concentration circulation subsystem via a pipeline, and the outlet of the concentration circulation subsystem is connected to the inlet of the electrodialysis membrane stack.

[0023] When the conductivity of the TMAH purified liquid at the TMAH purified liquid outlet is less than a preset second threshold, the TMAH purified liquid is transported to the concentration and circulation subsystem, and then re-enters the electrodialysis membrane stack for deep purification.

[0024] As a further improvement of this utility model, an ultrapure water circulation subsystem is provided between the front and rear ends of the electrodialysis membrane stack to replenish ultrapure water to the electrodialysis membrane stack and the concentrate circulation subsystem.

[0025] As a further improvement of this utility model, a concentrate pressure gauge is provided on the pipeline between the concentrate circulation subsystem and the electrodialysis membrane stack.

[0026] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0027] This invention removes suspended photoresist from TMAH waste liquid by setting up a preliminary purification subsystem. Simultaneously, by alternately treating the filtrate from raw material tanks A and B using an electrodialysis membrane stack, the photoresist on the electrodialysis membrane surface can be re-dissolved, preventing dissolved photoresist from clogging the electrodialysis membrane. This achieves zero discharge of hazardous waste and allows for complete recovery of the photoresist, resulting in very high economic and ecological value. Furthermore, this invention enables continuous recovery of TMAH waste liquid through the alternating treatment of the filtrate from raw material tanks A and B. Compared to existing technologies, this invention achieves zero system cleaning and zero photoresist loss, and the TMAH purified solution can be adjusted to the concentration required for production and directly reused. Attached Figure Description

[0028] Figure 1 is a schematic diagram of the preliminary purification subsystem in a continuously operating system for the recovery of TMAH waste liquid in the semiconductor industry, as disclosed in an embodiment of this utility model.

[0029] Figure 2 is a schematic diagram of a deep purification subsystem in a continuously operating TMAH waste liquid recovery system for the semiconductor industry, as disclosed in an embodiment of this utility model.

[0030] Explanation of reference numerals in the attached figures:

[0031] 100. Waste liquid feed tank; 101. Waste liquid feed tank level gauge; 102. Waste liquid feed pump; 103. Waste liquid feed flow meter; 104. Waste liquid feed pressure gauge; 105. Differential pressure gauge; 106. Primary filter; 107. Secondary filter; 108. Tertiary filter; 200. Raw material tank A; 201. Raw material tank level gauge A; 202. Raw material pump A; 203. Security filter A; 204. Raw material pressure gauge; 205. Raw material tank B; 206. Raw material tank 207. Level gauge B; 208. Raw material pump B; 209. Security filter B; 210. Electrodialysis membrane stack; 211. Conductivity meter; 212. External discharge electric valve; 213. Raw material tank A reflux electric valve; 214. Raw material tank B reflux electric valve; 215. Concentrate conductivity meter; 216. Concentrate collection electric valve; 217. Concentrate reflux electric valve; 218. Electrode water circulation subsystem; 219. Concentrate circulation subsystem; 220. Concentration matching subsystem. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0033] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, 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," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0034] 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.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings:

[0036] As shown in Figures 1 and 2, the present invention provides a continuous operation system for the recycling of TMAH waste liquid in the semiconductor industry, which includes a preliminary purification subsystem and a deep purification subsystem connected in sequence.

[0037] The preliminary purification subsystem includes a primary filter 106, a secondary filter 107, and a tertiary filter 108 connected in sequence.

[0038] As shown in Figure 2, the deep purification subsystem includes raw material tank A200 and raw material tank B205. The inlets of raw material tank A200 and raw material tank B205 are connected to the outlet of the preliminary purification subsystem. The outlets of both are connected to the electrodialysis membrane stack 209. The TMAH purified liquid outlet of the electrodialysis membrane stack 209 is connected to the concentration matching subsystem 220. The waste liquid outlet is connected to the reflux port of raw material tank A200 and raw material tank B205 and the TMAH waste liquid tank, respectively.

[0039] The TMAH waste liquid undergoes primary purification through filters 106, 107, and 108 to remove suspended photoresist. The filtered liquid then enters raw material tanks A200 and B205 of the deep purification subsystem. The filtered liquid from raw material tanks A200 and B205 is alternately circulated into the electrodialysis membrane stack 209 for deep purification. The deeply purified TMAH solution is then sent to the concentration matching subsystem 220, and the remaining waste liquid is discharged. Specifically, TMAH waste liquid is introduced into the preliminary purification subsystem via the waste liquid feeding system. Through multi-stage filtration, suspended photoresist in the liquid is separated and retained, achieving preliminary purification. The filtered liquid is collected into the deep purification subsystem for further deep purification. After TMAH purification in raw material tank A200 is completed, the system automatically switches to raw material tank B205. During the circulation process, the TMAH waste liquid in raw material tank B205 can dissolve the photoresist adhering to the surface of the electrodialysis membrane. After purification, it switches back to raw material tank A for further purification. This cycle repeats continuously, achieving zero system cleaning and zero photoresist loss. The purified TMAH liquid can be further purified using nanofiltration or low-temperature evaporation, or its concentration can be directly adjusted to the required concentration for production and reused.

[0040] in,

[0041] As shown in Figure 1, this utility model also includes a waste liquid feeding subsystem connected to the front end of the preliminary purification subsystem; TMAH waste liquid is pumped into the filtration system through the waste liquid feeding subsystem; specifically, the waste liquid feeding subsystem includes a waste liquid feeding tank 100 and a waste liquid feeding pump 102. A level gauge for the waste liquid feeding tank 100 is installed on the waste liquid feeding tank 100 (specifically installed on the side wall near the bottom of the waste liquid feeding tank 100). The outlet of the waste liquid feeding tank 100 is connected to the suction port of the waste liquid feeding pump 102. The waste liquid feeding tank 100 receives the TMAH waste liquid discharged from the production system, and the waste liquid feeding pump 102 pumps the TMAH waste liquid in the waste liquid feeding tank 100 to the primary filter 106 of the preliminary purification subsystem.

[0042] As shown in Figure 1, a waste liquid feed flow meter 103 and a waste liquid feed pressure gauge 104 are installed on the pipeline between the waste liquid feed pump 102 and the preliminary purification subsystem. The level gauge of the waste liquid feed tank 100 is interlocked with the waste liquid feed pump 102 to control the start and stop of the waste liquid feed pump 102. The waste liquid feed flow meter 103 and the waste liquid feed pressure gauge 104 monitor the feed flow and pressure.

[0043] As shown in Figure 1, the primary filter 106, secondary filter 107, and tertiary filter 108 of this invention are all equipped with PP cotton pleated filter elements, with filtration accuracies of 50μm, 30μm, and 5μm, respectively. The three-stage filtration progressively intercepts and separates the suspended photoresist in the TMAH waste liquid, achieving preliminary purification. The effluent then enters the deep purification system. Furthermore, a differential pressure gauge 105 is installed between the inlet of the primary filter 106 and the outlet of the tertiary filter 108. The differential pressure gauge 105 monitors the pressure difference before and after the filtration system. Based on the monitoring data from the differential pressure gauge 105, the filter elements of the tertiary filter are replaced periodically.

[0044] As shown in Figure 2, the deep purification subsystem includes a secondary electrodialysis feed subsystem, which includes raw material tanks A200 and B205, and security filters A203 and B208 connected to the outlets of raw material tanks A200 and B205 respectively via raw material pumps A202 and B207. The suction ports of raw material pumps A202 and B207 are connected to the outlets of raw material tanks A200 and B205. A raw material pressure gauge 204 and a flow meter are installed on the main pipe after the pump pipelines converge. The security filters are equipped with PP cotton pleated filter elements with a filtration accuracy of 5μm. The inlets of security filters A203 and B208 are connected to the outlets of raw material pumps A202 and B207 respectively. The outlet of the security filters is connected to the inlet of the deep purification subsystem, specifically to the inlet of the electrodialysis membrane stack 209.

[0045] Furthermore, raw material tanks A200 and B205 are respectively equipped with level gauges for raw material tank A200 and B205. These level gauges are interlocked with raw material pumps A202 and B207, respectively, to control the start and stop of their operation. The raw material pressure gauge 204 monitors the operating pressure and can indicate whether there is any blockage in the channels of the deep purification subsystem.

[0046] As shown in Figure 2, the waste liquid outlet of the electrodialysis membrane stack 209 is equipped with a conductivity meter 210; when the conductivity of the remaining waste liquid passing through the waste liquid outlet is less than a preset first threshold, the remaining waste liquid is discharged to the TMAH waste liquid tank; when the conductivity of the remaining waste liquid passing through the waste liquid outlet is greater than or equal to the preset first threshold, the remaining waste liquid is returned to the raw material tank A200 or raw material tank B205 corresponding to the current processing through the return port.

[0047] Furthermore, the waste liquid outlet of the electrodialysis membrane stack 209 is first connected to the TMAH waste liquid tank via a pipeline, and then connected to the return ports of raw material tanks A200 and B205. The front end of the TMAH waste liquid tank is equipped with an external discharge electric valve 211. The pipelines connected to the return ports of raw material tanks A200 and B205 are respectively equipped with return electric valves for raw material tanks A200 and B205. By controlling the opening of the return electric valves for raw material tanks A200 or B205, the remaining waste liquid corresponding to the raw material tank being processed is returned to raw material tanks A200 or B205 through the return port to achieve recycling. The conductivity meter 210 can reflect the degree of TMAH recovery. After the recovery is completed, the external discharge electric valve 211 is opened to discharge the remaining waste liquid to the TMAH waste liquid tank.

[0048] As shown in Figure 2, the TMAH purified solution outlet of the electrodialysis membrane stack 209 is equipped with a concentrate conductivity meter 214. When the conductivity of the TMAH purified solution passing through the outlet is greater than or equal to a preset second threshold, the TMAH purified solution is transported to the concentration matching subsystem 220. The TMAH purified solution outlet of the electrodialysis membrane stack 209 is connected to the inlet of the concentration circulation subsystem via a pipeline, and the outlet of the concentration circulation subsystem is connected to the inlet of the electrodialysis membrane stack 209. When the conductivity of the TMAH purified solution passing through the outlet is less than the preset second threshold, the TMAH purified solution is transported to the concentration circulation subsystem, and then re-enters the electrodialysis membrane stack 209 for further purification.

[0049] Furthermore, the TMAH purified liquid outlet is first connected to the concentration matching subsystem 220 via a pipeline, and then connected to the concentrate circulation subsystem 218. A concentrate recovery electric valve is provided between the TMAH purified liquid outlet and the concentration matching subsystem 220, and a concentrate return electric valve 216 is provided on the pipeline between the outlet and the concentrate circulation subsystem 218.

[0050] Specifically, the concentrate conductivity meter 214 can reflect whether the concentration of TMAH recovery meets the recovery requirements. When the recovery requirements are not met, the concentrate collection electric valve 215 is closed and the concentrate return electric valve 216 is opened. When the recovery requirements are met, the concentrate collection electric valve 215 is opened and the concentrate return electric valve 216 is closed. After a single recovery is completed, ultrapure water is added through the electrode water circulation subsystem 217 and enters the concentrate circulation subsystem 218 and the electrodialysis membrane stack 209 for repeated operation.

[0051] In this invention, a concentrate pressure gauge 219 is installed on the pipeline between the concentrate circulation subsystem 218 and the electrodialysis membrane stack 209. The concentrate pressure gauge 219 can reflect the blockage of the concentrate channel.

[0052] In this invention, a nanofiltration subsystem can be set at the front end of the concentration matching subsystem 220 for further purification.

[0053] Example 1:

[0054] The photolithography developer waste liquid, after passing through the waste lifting system, enters the preliminary purification system. Suspended photoresist is filtered out by the three-stage filter 108, yielding a preliminary purified solution. This preliminary purified solution then enters the deep purification system. The feeding system has two series, A and B. First, the preliminary purified solution fills raw material tanks A200 and B205 before running series A. When the conductivity of series A reaches below 10 mS / cm, the external discharge electric valve 211 opens, discharging the waste liquid from raw material tank A200 into the TMAH waste liquid tank. Simultaneously, the deep purification process begins. In the system, the electrodialysis membrane stack 209, concentrate circulation subsystem 218, and electrode water circulation subsystem 217 are de-energized. Then, the B-series circulation is switched on. Two minutes after the B-series circulation starts, the electrodialysis membrane stack 209, concentrate circulation subsystem 218, and electrode water circulation subsystem 217 in the deep purification system are energized. When the conductivity of the B-series reaches below 10 mS / cm, the external discharge electric valve 211 is opened to discharge the waste liquid in the raw material tank B205 into the TMAH waste liquid tank. At the same time, the electrodialysis system is de-energized, and then the A-series circulation is switched on. This cycle is repeated. When the concentrate conductivity reaches 70 mS / cm, the concentrate collection electric valve 215 is opened to recover the concentrate into the concentration matching system for dilution and temperature adjustment, forming a 2.38% TMAH product solution that is then recycled into the production system for reuse.

[0055] Example 2:

[0056] The photolithography developer waste liquid, after passing through the waste lifting system, enters the preliminary purification system. Suspended photoresist is filtered out by the three-stage filter 108, yielding a preliminary purified solution. This preliminary purified solution then enters the deep purification system. The feeding system has two series, A and B. First, the preliminary purified solution fills raw material tanks A200 and B205 before running series A. When the conductivity of series A reaches below 10 mS / cm, the external discharge electric valve 211 opens, discharging the waste liquid from raw material tank A200 into the TMAH waste liquid tank. Simultaneously, the deep purification process begins. In the system, the electrodialysis membrane stack 209, concentrate circulation subsystem 218, and electrode water circulation subsystem 217 are de-energized, and then the B-series circulation is switched on. Two minutes after the B-series circulation starts, the electrodialysis membrane stack 209, concentrate circulation subsystem 218, and electrode water circulation subsystem 217 in the deep purification system are energized. When the conductivity of the B-series reaches below 10 mS / cm, the external discharge electric valve 211 is opened to discharge the waste liquid in the raw material tank B205 into the TMAH waste liquid tank. At the same time, the electrodialysis system is de-energized, and then the A-series circulation is switched on. This cycle is repeated. When the conductivity of the concentrate reaches 70 mS / cm, the concentrate collection electric valve 215 is opened to recover the concentrate to the nanofiltration subsystem. The nanofiltration subsystem can further concentrate the TMAH developer, with a recovery rate set at 60%. The nanofiltration permeate can enter the TMAH waste liquid tank, and the nanofiltration concentrate can be collected and stored. It can be introduced into the concentration matching system for dilution and temperature adjustment as needed to form a 2.38% TMAH product liquid for reuse in the production system.

[0057] Example 3:

[0058] The photolithography developer waste liquid, after passing through the waste lifting system, enters the preliminary purification system. Suspended photoresist is filtered out by the three-stage filter 108, yielding a preliminary purified solution. This preliminary purified solution then enters the deep purification system. The feeding system has two series, A and B. First, the preliminary purified solution fills raw material tanks A200 and B205 before running series A. When the conductivity of series A reaches below 10 mS / cm, the external discharge electric valve 211 opens, discharging the waste liquid from raw material tank A200 into the TMAH waste liquid tank. Simultaneously, the deep purification process begins. In the system, the electrodialysis membrane stack 209, concentrate circulation subsystem 218, and electrode water circulation subsystem 217 are de-energized. Then, the B-series circulation is switched on. Two minutes after the B-series circulation starts, the electrodialysis membrane stack 209, concentrate circulation subsystem 218, and electrode water circulation subsystem 217 in the deep purification system are energized. When the conductivity of the B-series reaches below 10 mS / cm, the external discharge electric valve 211 is opened to discharge the waste liquid in the raw material tank B205 into the TMAH waste liquid tank. At the same time, the electrodialysis system is de-energized, and then the A-series circulation is switched on. This cycle is repeated. When the concentrate conductivity reaches 70 mS / cm, the concentrate collection electric valve 215 is opened to recover the concentrate to the low-temperature evaporation system. The evaporated liquid is collected into the TMAH waste liquid tank after cooling. The crystallized product is TMAH solid, which is introduced into the concentration matching system for dilution according to requirements to form a 2.38% TMAH product liquid for reuse in the production system.

[0059] Advantages of this utility model:

[0060] This invention removes suspended photoresist from TMAH waste liquid by setting up a preliminary purification subsystem. Simultaneously, by alternately treating the filtrate from raw material tanks A and B using an electrodialysis membrane stack, the photoresist on the electrodialysis membrane surface can be re-dissolved, preventing dissolved photoresist from clogging the electrodialysis membrane. This achieves zero discharge of hazardous waste and allows for complete recovery of the photoresist, resulting in very high economic and ecological value. Furthermore, this invention enables continuous recovery of TMAH waste liquid through the alternating treatment of the filtrate from raw material tanks A and B. Compared to existing technologies, this invention achieves zero system cleaning and zero photoresist loss, and the TMAH purified solution can be adjusted to the concentration required for production and directly reused.

[0061] The above are merely preferred embodiments of this utility model and do not limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A continuously operating system for recycling TMAH waste liquid in the semiconductor industry, characterized in that: The system includes a preliminary purification subsystem and a deep purification subsystem connected in sequence. The preliminary purification subsystem includes a primary filter, a secondary filter, and a tertiary filter connected in sequence. The deep purification subsystem includes raw material tank A and raw material tank B. The inlets of raw material tank A and raw material tank B are connected to the outlet of the preliminary purification subsystem, and the outlets of both are connected to an electrodialysis membrane stack. The TMAH purified liquid outlet of the electrodialysis membrane stack is connected to a concentration matching subsystem, and the waste liquid outlet is connected to the reflux outlet of raw material tank A and raw material tank B and a TMAH waste liquid tank, respectively. The TMAH waste liquid passes through the primary, secondary, and tertiary filters of the preliminary purification subsystem to remove suspended photoresist. The filtered liquid enters the raw material tanks A and B of the deep purification subsystem. The filtered liquid in raw material tanks A and B alternately enters the electrodialysis membrane stack for deep purification treatment. The deeply purified TMAH purified liquid is sent to the concentration matching subsystem, and the remaining waste liquid is discharged.

2. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 1, characterized in that: It also includes a waste liquid feeding subsystem connected to the front end of the preliminary purification subsystem; the waste liquid feeding subsystem includes a waste liquid feeding tank and a waste liquid feeding pump, the waste liquid feeding tank is equipped with a waste liquid feeding tank level gauge, and the outlet of the waste liquid feeding tank is connected to the suction port of the waste liquid feeding pump.

3. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 2, characterized in that: The pipeline between the waste liquid feed pump and the preliminary purification subsystem is equipped with a waste liquid feed flow meter and a waste liquid feed pressure meter.

4. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 1, characterized in that: The primary, secondary, and tertiary filters are all equipped with PP cotton pleated filter elements, with filtration accuracies of 50μm, 30μm, and 5μm, respectively.

5. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 1, characterized in that: The outlets of raw material tank A and raw material tank B are respectively connected to security filter A and security filter B, and the outlets of security filter A and security filter B are connected to the electrodialysis membrane stack.

6. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 1, characterized in that: The waste liquid outlet of the electrodialysis membrane stack is equipped with a conductivity meter; when the conductivity of the remaining waste liquid passing through the waste liquid outlet is less than a preset first threshold, the remaining waste liquid is discharged to the TMAH waste liquid tank; when the conductivity of the remaining waste liquid passing through the waste liquid outlet is greater than or equal to the preset first threshold, the remaining waste liquid corresponding to the raw material tank being processed is returned to the raw material tank A or raw material tank B through the return port.

7. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 1, characterized in that: The TMAH purified liquid output port of the electrodialysis membrane stack is equipped with a concentrated water conductivity meter; when the conductivity of the TMAH purified liquid passing through the TMAH purified liquid output port is greater than or equal to a preset second threshold, the TMAH purified liquid is transported to the concentration matching subsystem.

8. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 7, characterized in that: The TMAH purified solution outlet of the electrodialysis membrane stack is connected to the inlet of the concentration circulation subsystem via a pipeline, and the outlet of the concentration circulation subsystem is connected to the inlet of the electrodialysis membrane stack. When the conductivity of the TMAH purified solution passing through the TMAH purified solution outlet is less than a preset second threshold, the TMAH purified solution is transported to the concentration circulation subsystem, and after passing through the concentration circulation subsystem, it re-enters the electrodialysis membrane stack for deep purification.

9. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 8, characterized in that: An ultrapure water circulation subsystem is provided between the front and rear ends of the electrodialysis membrane stack to replenish ultrapure water to the electrodialysis membrane stack and the concentration circulation subsystem.

10. The system for continuous operation of TMAH waste liquid recovery in the semiconductor industry according to claim 8, characterized in that: A concentrate pressure gauge is installed on the pipeline between the concentration circulation subsystem and the electrodialysis membrane stack.

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