Constant temperature system suitable for wafer polishing solution

Abstract

The invention relates to the technical field of wafer polishing solution constant temperature control, in particular to a constant temperature system suitable for wafer polishing solution, which comprises temperature monitoring position adjustment, circulation pipeline design, negative pressure drainage design and backflow cooling design. A high-precision temperature sensor is mounted at an outlet of a liquid outlet pipeline, and a self-circulation pipeline and a non-contact heating device are combined, so that polishing liquid is uniformly heated; the negative pressure drainage device ensures that liquid quickly reaches a monitoring point; the cooling coil and the temperature sensor cooperate to manage the temperature of backflow liquid. According to the application, a temperature monitoring blind area can be eliminated, local overheating and heat loss deviation are avoided, the system response speed and the temperature control precision are improved, and the reliability and the stability are enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a constant temperature system suitable for wafer polishing liquid. Background Art

[0002] In the wafer polishing process, controlling the temperature of the polishing slurry has a significant impact on polishing quality, surface roughness, and product yield. However, existing polishing slurry constant temperature control methods and systems still have some shortcomings in practical applications, especially in the selection of temperature monitoring locations, contact methods with heat sources, and temperature regulation of the reflux liquid. These methods and systems fail to fully meet the requirements of high-precision polishing processes.

[0003] After searching, a polishing liquid supply system with the publication number CN108284390B was disclosed, and the publication date is July 18, 2023. This patent realizes the constant temperature of the polishing liquid through a constant temperature control module, and combines the PLC control system to realize the timing, quantitative delivery and automatic alarm functions. However, in this technical solution, the temperature monitoring point is located in the polishing liquid dispensing barrel, rather than at the outlet of the liquid outlet pipe, which may cause a deviation between the actual temperature of the polishing liquid flowing into the polishing machine and the set value, making it difficult to achieve refined temperature control. In addition, the system uses the traditional liquid level mode for reflux management, and does not effectively adjust the temperature of the reflux liquid, which may have a certain impact on the recycling effect of the polishing liquid.

[0004] After searching, a chemical mechanical polishing equipment and its temperature control system with publication number CN111512425B were disclosed, and the publication date is May 30, 2025. This patent directly contacts the polishing surface or polishing liquid through a thermal control module to achieve temperature control during the polishing process. However, in this technical solution, the heat source is in direct contact with the polishing liquid or the polishing surface, which may cause problems of local excessive temperature or uneven distribution, thereby adversely affecting the polishing quality. In addition, the system does not monitor and regulate the temperature of the polishing liquid that is reused after flowing out of the polishing machine, which may cause large temperature fluctuations in the reflux liquid, thereby affecting the stability of the polishing process.

[0005] The above issues indicate that existing wafer polishing liquid constant temperature control methods and systems still have certain limitations in terms of optimizing the temperature monitoring location, non-contact heat source design, and temperature management mode of the reflux liquid. Therefore, the present invention provides a novel wafer polishing liquid constant temperature control method and system. This method aims to achieve refined control of the polishing liquid temperature by adjusting the temperature monitoring location to the outlet of the liquid outlet pipe, modifying the existing polishing liquid reflux tank to achieve temperature mode management, and adopting a non-contact heat source design, thereby ensuring that the temperature fluctuation range does not exceed 0.1 degrees Celsius, ultimately improving the polishing quality and product surface particle level. Summary of the Invention

[0006] The object of the present invention is to provide a constant temperature system suitable for wafer polishing liquid to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a constant temperature system for wafer polishing liquid, comprising the following steps:

[0008] Step 1: Adjust the temperature monitoring position

[0009] A high-precision temperature sensor is installed at the outlet of the liquid pipe, at the end of the path where the polishing fluid flows from the mixing tank to the processing machine. The temperature sensor is fixed to the inner wall of the pipe via a threaded connection, and the temperature sensor output signal is transmitted to the PLC control system (model Siemens S7-1200) via a 4-20mA current loop. As the polishing fluid flows through the outlet, the temperature sensor measures the liquid temperature in real time and transmits it to the control system. This temperature data is compared with the set value (range: 20°C to 30°C). If the absolute deviation is ≥0.05°C, the heating or cooling device adjustment command is triggered.

[0010] Step 2: Circulation Pipeline Design

[0011] A self-circulating pipeline is installed inside the liquid distribution barrel. The self-circulating pipeline is made of stainless steel and spirally arranged along the side wall of the barrel. Its two ends are connected to the bottom and top of the barrel respectively through flanges. One end of the self-circulating pipeline is connected to the liquid inlet at the bottom of the barrel, and the other end is connected to the liquid outlet at the top of the barrel. A non-contact heating device is installed on the outer wall of the self-circulating pipeline. The heating device uses an electromagnetic induction coil, which is fixed to the outer wall of the pipeline by a clip. When the polishing liquid enters the self-circulating mode, the liquid flows in the pipeline. The operating frequency of the electromagnetic induction coil is 20kHz to 30kHz. Combined with the spiral arrangement of the stainless steel self-circulating pipeline, CFD fluid simulation verification shows that the heat distribution uniformity error is ≤5%.

[0012] Step 3: Negative pressure drainage design

[0013] A negative pressure drainage device, consisting of a diaphragm pump and a drainage tube, is installed at the inlet of the liquid outlet pipe. One end of the drainage tube is inserted into the bottom of the liquid dispensing bucket, and the other end is connected to the liquid inlet of the diaphragm pump via a quick connector. The liquid outlet of the diaphragm pump is connected to the liquid outlet pipe. When the diaphragm pump is activated, negative pressure is generated in the drainage tube, drawing the polishing liquid from the liquid dispensing bucket into the liquid outlet pipe, ensuring that the liquid quickly reaches the temperature sensor.

[0014] Step 4. Reflux cooling design: A cooling unit is set up in the polishing liquid recovery box. The cooling unit consists of a cooling coil and a temperature sensor. The cooling coil is made of copper and is spirally arranged at the bottom of the recovery box. Its two ends are connected to the external cooling water supply system through threaded connections. The surface of the cooling coil is covered with a thermal conductive silicone layer to enhance the heat conduction efficiency. The temperature sensor is installed on the inner wall of the recovery box, and its probe is immersed in the polishing liquid for real-time monitoring of the liquid temperature. When it is detected that the polishing liquid temperature is higher than the set value, the cooling water supply system starts, and cold water flows in the coil to absorb the heat of the polishing liquid.

[0015] In a further optimization of the above technical solution, the high-precision temperature sensor is a platinum resistance temperature sensor with a measurement range of 0°C to 100°C and a measurement accuracy of ±0.05°C.

[0016] In a further optimization of the above technical solution, the electromagnetic induction coil of the non-contact heating device has an operating frequency of 20kHz to 30kHz, and the surface of the coil is coated with a high-temperature resistant insulating coating with a thickness of 0.5mm to 1mm.

[0017] In a further optimization of the above technical solution, the spiral diameter of the cooling coil is 10 cm to 15 cm, the coil spacing is 2 cm to 3 cm, and the total coil length is 5 m to 8 m.

[0018] As a further optimization of the above technical solution, the body of the polishing liquid recovery box adopts a double-layer structure, with the outer layer being made of stainless steel and the inner layer being a polytetrafluoroethylene coating with a coating thickness of 0.3mm to 0.5mm to improve corrosion resistance.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention eliminates the blind spot problem of the temperature monitoring point located in the liquid distribution barrel in the traditional technology by installing the temperature sensor at the outlet of the liquid outlet pipe. The temperature of the polishing liquid is directly detected when it flows out of the pipe, avoiding temperature deviation caused by heat loss in the pipe. The design of the self-circulating pipeline combined with the non-contact heating device allows the polishing liquid to be evenly heated during the circulation process in the barrel, solving the problem of local overheating that may be caused by traditional heating methods. The application of the negative pressure drainage device ensures that the polishing liquid can quickly reach the temperature sensor position, thereby improving the response speed of the system. The use of the cooling coil and the temperature sensor realizes the precise management of the temperature of the reflux polishing liquid, avoiding the influence of high-temperature reflux liquid on the processing process. The overall design enhances the reliability and stability of the system while improving the temperature control accuracy of the polishing liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall system structure of the present invention.

[0021] Figure 2This is a partial enlarged view of the outlet of the liquid pipe.

[0022] Figure 3 This is a schematic diagram of the layout of the self-circulating pipeline inside the liquid distribution barrel.

[0023] Figure 4 This is a schematic diagram of the structure of the negative pressure drainage device.

[0024] Figure 5 This is the layout diagram of the cooling unit in the polishing liquid recovery tank.

[0025] In the figure: 1. Liquid mixing barrel; 2. Liquid outlet pipe; 3. High-precision temperature sensor; 4. Self-circulating pipeline; 5. Flange; 6. Electromagnetic induction coil; 7. Diaphragm pump; 8. Drainage pipe; 9. Quick connector; 10. Polishing liquid recovery tank; 11. Cooling coil; 12. Temperature sensor; 13. Thermal conductive silicone layer; 14. Cooling water supply system. DETAILED DESCRIPTION

[0026] The present invention provides a constant temperature system suitable for wafer polishing liquid, and its specific implementation is as follows: Figures 1 to 5 First, the structure of the overall system is as follows Figure 1 As shown, the system includes a liquid dispensing tank 1, a liquid outlet pipe 2, a high-precision temperature sensor 3, a self-circulating pipeline 4, a diaphragm pump 7, a drainage pipe 8, a polishing liquid recovery tank 10, a cooling coil 11, a temperature sensor 12, and related connecting components and auxiliary devices. These components achieve constant temperature control of the wafer polishing liquid through a specific connection relationship and position arrangement.

[0027] The liquid dispensing barrel 1 is the core container of the entire system, used for storing and preliminarily treating the polishing liquid. A self-circulating pipeline 4 is set inside the liquid dispensing barrel 1. The self-circulating pipeline 4 is made of stainless steel and is firmly connected to the bottom and top of the barrel through flanges 5. The self-circulating pipeline 4 is arranged in a spiral shape along the side wall of the barrel. This design allows the polishing liquid to flow evenly in the barrel and receive heating treatment. The outer wall of the self-circulating pipeline 4 is equipped with a non-contact heating device, which mainly consists of an electromagnetic induction coil 6, such as Figure 2 As shown. The electromagnetic induction coil 6 is secured to the outer wall of the self-circulating pipe 4 via a clip and coated with a high-temperature insulating coating with a thickness of 0.5mm to 1mm to prevent the coil from being damaged by high temperatures. The electromagnetic induction coil 6 operates at a frequency of 20kHz to 30kHz, efficiently converting electrical energy into heat energy and transferring it to the liquid in the pipe.

[0028] One end of the liquid outlet pipe 2 is connected to the outlet of the liquid dispensing barrel 1, and the other end extends to the processing machine. A high-precision temperature sensor 3 is installed at the outlet of the liquid outlet pipe 2. Figure 2As shown. The high-precision temperature sensor 3 is fixed to the inner wall of the pipe through a threaded connection, and the temperature sensor output signal is transmitted to the PLC control system (model Siemens S7-1200) through a 4-20mA current loop. The sensor adopts a platinum resistance type design, with a measurement range of 0℃ to 100℃ and a measurement accuracy of ±0.05℃. When the polishing liquid flows out of the liquid mixing barrel 1, the high-precision temperature sensor 3 detects the liquid temperature in real time and transmits the data to the control system. The control system uses a PID algorithm, and the formula is as follows:

[0029]

[0030] (Proportional coefficient Kp = 0.8, integral time Ti = 120s, differential time Td = 30s), when the detected temperature deviation |e(t)| = |T set -T actual |≥0.05℃, heating adjustment: P new =P current ±10%, cooling trigger: start the cooling water supply system.

[0031] In order to ensure that the polishing liquid can quickly reach the location of the high-precision temperature sensor 3, a negative pressure drainage device is set at the inlet of the liquid outlet pipe 2. The negative pressure drainage device consists of a diaphragm pump 7 and a drainage pipe 8. Figure 4 As shown in the figure, one end of drainage tube 8 is inserted into the bottom of liquid dispensing barrel 1, and the other end is connected to the liquid inlet of diaphragm pump 7 via quick connector 9. The liquid outlet of diaphragm pump 7 is connected to liquid outlet pipe 2. When diaphragm pump 7 is started, negative pressure is generated in drainage tube 8, which draws the polishing liquid in liquid dispensing barrel 1 into liquid outlet pipe 2, significantly improving the system's response speed.

[0032] After use, the polishing liquid will enter the polishing liquid recovery box 10 for processing. Figure 5 As shown, a cooling unit is provided in the polishing liquid recovery tank 10, and the cooling unit consists of a cooling coil 11 and a temperature sensor 12. The cooling coil 11 is made of copper and is arranged in a spiral shape at the bottom of the recovery tank. Its two ends are connected to the external cooling water supply system 14 through threaded connections. The spiral diameter of the cooling coil 11 is 10cm to 15cm, the coil spacing is 2cm to 3cm, and the total length is 5m to 8m. This design can maximize the cooling efficiency. The surface of the cooling coil 11 is covered with a thermally conductive silicone layer 13 to enhance the heat conduction performance. The temperature sensor 12 is installed on the inner wall of the recovery tank, and the probe is immersed in the polishing liquid for real-time monitoring of the liquid temperature. When the temperature sensor 12 detects that the polishing liquid temperature is higher than the set value, the cooling water supply system 14 is started, and the cooling water flow control range is 5-10L / min. Cold water flows in the coil 11, absorbing the heat of the polishing liquid, thereby achieving a cooling effect.

[0033] Furthermore, the polishing liquid recovery tank 10 features a double-layer design, with a stainless steel outer layer and a polytetrafluoroethylene inner layer with a thickness of 0.3mm to 0.5mm. This design not only enhances the corrosion resistance of the tank but also effectively isolates the polishing liquid from the external environment. Furthermore, the double-layer structure provides a certain degree of insulation, reducing heat loss.

[0034] During actual operation, after the polishing liquid flows out of the liquid distribution barrel 1, it passes through the self-circulating pipeline 4, the liquid outlet pipe 2 and the high-precision temperature sensor 3 in sequence, and finally reaches the processing machine. During this process, the self-circulating pipeline 4 and the electromagnetic induction coil 6 work together to ensure that the polishing liquid is evenly heated in the barrel to avoid local overheating. The high-precision temperature sensor 3 monitors the temperature changes of the polishing liquid in real time and feeds the data back to the control system. If the temperature deviates from the set value, the control system will automatically adjust the power of the electromagnetic induction coil 6 or start the cooling water supply system 14 to maintain the constant temperature of the polishing liquid. At the same time, the negative pressure drainage device ensures that the polishing liquid can quickly reach the location of the temperature sensor through the action of the diaphragm pump 7 and the drainage tube 8, thereby improving the response speed of the system. During the polishing liquid recovery stage, the cooling coil 11 and the temperature sensor 12 work together to accurately manage the reflux liquid to avoid the adverse effects of high-temperature reflux liquid on the processing process.

[0035] The connection relationship and position layout between the above-mentioned components have been carefully designed to ensure stable and reliable operation of the entire system. For example, the spiral arrangement of the self-circulating pipeline 4 not only optimizes the liquid flow path, but also improves the heating efficiency; the spiral design of the cooling coil 11 makes full use of the limited space and enhances the cooling effect. In addition, the material selection of each component has also been strictly considered. For example, the self-circulating pipeline 4 and the cooling coil 11 made of stainless steel have excellent corrosion resistance and thermal conductivity, and the polytetrafluoroethylene coating further enhances the corrosion resistance of the system. Through these detailed designs, the present invention achieves precise control of the temperature of the wafer polishing liquid and meets the strict requirements of high-end manufacturing processes for constant temperature conditions.

[0036] The above content describes the specific implementation of the present invention in detail, covering the connection relationship, position arrangement and mutual coordination relationship of each component, and is fully illustrated in conjunction with the accompanying drawings. Those skilled in the art can fully implement the technical solution of the present invention based on the above content.

[0037] In order to better enable relevant personnel in this technical field to fully understand and implement the present invention, the specific implementation principle of the present invention is supplemented below with reference to a specific application scenario.

[0038] First, the operator injects the polishing liquid into the liquid distribution barrel 1, and the liquid begins to flow through the self-circulating pipe 4. The self-circulating pipe 4 is arranged in a spiral shape along the side wall of the barrel to ensure that the polishing liquid is evenly distributed in the barrel. At this time, the electromagnetic induction coil 6 is started, and the operating frequency is set to 20kHz~30kHz. The electrical energy is converted into thermal energy through the electromagnetic induction effect, and the heat is transferred to the internal liquid through the self-circulating pipe 4 made of stainless steel. Since the outer wall of the pipeline is coated with a high-temperature resistant insulating coating with a thickness of 0.5mm~1mm, the electromagnetic induction coil 6 can operate stably in a high-temperature environment to avoid damage caused by overheating. This non-contact heating method effectively solves the problem of local overheating that may be caused by traditional direct contact heating, while improving the heat transfer efficiency.

[0039] Subsequently, the diaphragm pump 7 is started and the negative pressure drainage device begins to work. One end of the drainage tube 8 is inserted into the bottom of the liquid dispensing barrel 1, and the other end is connected to the diaphragm pump 7 through the quick connector 9. The liquid outlet of the diaphragm pump 7 is connected to the liquid outlet pipe 2. Under the action of the diaphragm pump 7, a negative pressure is formed in the drainage tube 8, which attracts the polishing liquid in the liquid dispensing barrel 1 to flow quickly into the liquid outlet pipe 2. This design significantly shortens the time it takes for the polishing liquid to reach the location of the high-precision temperature sensor 3 from the liquid dispensing barrel 1, thereby improving the response speed of the system. The high-precision temperature sensor 3 is fixed at the outlet of the liquid outlet pipe 2 through a threaded connection. Its probe is in direct contact with the polishing liquid, detecting the liquid temperature in real time and transmitting the data to the control system. The control system compares the received temperature data with the preset value. If it is found that the temperature deviates from the set value, it automatically adjusts the power of the electromagnetic induction coil 6 or starts the cooling water supply system 14 to maintain the constant temperature of the polishing liquid.

[0040] After the polishing liquid flows through the processing machine, the liquid enters the polishing liquid recovery tank 10 for treatment. The cooling coil 11 is arranged in a spiral shape at the bottom of the recovery tank, and its two ends are connected to the external cooling water supply system 14 through threaded connections. When the temperature sensor 12 detects that the polishing liquid temperature is higher than the set value, the cooling water supply system 14 is activated, and cold water flows in the coil 11 and absorbs the heat of the polishing liquid through the thermal conductive silicone layer 13, thereby achieving a cooling effect. The spiral diameter of the cooling coil 11 is designed to be 10cm to 15cm, the coil spacing is 2cm to 3cm, and the total length is 5m to 8m. This structure makes full use of the limited space and maximizes the cooling efficiency. In addition, the polishing liquid recovery tank 10 adopts a double-layer structure design, with the outer layer made of stainless steel and the inner layer coated with polytetrafluoroethylene with a coating thickness of 0.3mm to 0.5mm. This design not only enhances the corrosion resistance of the box, but also effectively isolates the impact of the external environment on the polishing liquid, while also playing a certain insulation role and reducing heat loss.

[0041] The entire system achieves precise control of the temperature of the wafer polishing liquid through the coordinated work of the above-mentioned components. For example, the spiral arrangement of the self-circulating pipeline 4 optimizes the liquid flow path, ensuring that the polishing liquid is evenly heated in the barrel; the spiral design of the cooling coil 11 makes full use of the limited space and enhances the cooling effect. At the same time, the material selection of each component has also been strictly considered. The self-circulating pipeline 4 and the cooling coil 11 made of stainless steel have excellent corrosion resistance and thermal conductivity, and the polytetrafluoroethylene coating further enhances the corrosion resistance of the system. Through these detailed designs, the present invention can control the temperature fluctuation range of the polishing liquid to within 0.1°C, meeting the strict requirements of high-end manufacturing processes for constant temperature conditions.

[0042] The experimental data table of the present invention and the traditional method is as follows: Test conditions: 25°C constant temperature environment; polishing liquid: SiO2 based (concentration 12wt%);

[0043]

[0044] Based on Newton's law of cooling (Q = h·A·ΔT) in the table above, by optimizing the coil spiral diameter (10-15cm), spacing (2-3cm), and length (5-8m), the heat exchange area is increased by 150%. Combined with the copper material's thermal conductivity of 398W / (m·K), a cooling rate of 2.0°C / min is achieved.

[0045] The above content describes in detail the implementation steps and operating principles of the present invention in specific application scenarios. Those skilled in the art can fully implement the technical solution of the present invention based on the above content. The contents not described in detail in the specification belong to the existing technology well known to those skilled in the art, and the model parameters of each electrical appliance are not specifically limited, and conventional equipment can be used. The electrical control components not mentioned in this technical solution are not shown in the figure because they belong to the existing technology and are not described here.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling the constant temperature of a wafer polishing liquid, characterized in that The following steps are involved: Step 1: Adjust the temperature monitoring position A high-precision temperature sensor is installed at the outlet of the liquid outlet pipe, at the end of the path where the polishing liquid flows from the liquid mixing barrel to the processing machine. The high-precision temperature sensor is fixed to the inner wall of the pipe through a threaded connection and is electrically connected to the control system. As the polishing liquid flows through the outlet, the high-precision temperature sensor detects the liquid temperature in real time and transmits the data to the control system. Step 2: Circulation Pipeline Design A self-circulating pipeline is installed inside the liquid distribution barrel. The self-circulating pipeline is made of stainless steel and spirally arranged along the side wall of the barrel. Its two ends are connected to the barrel bottom and barrel top respectively through flanges. One end of the self-circulating pipeline is connected to the liquid inlet at the bottom of the barrel, and the other end is connected to the liquid outlet at the top of the barrel. The outer wall of the self-circulating pipeline is equipped with a non-contact heating device. The non-contact heating device uses an electromagnetic induction coil and is fixed to the outer wall of the pipeline with a buckle. Step 3: Negative pressure drainage design A negative pressure drainage device is installed at the inlet of the liquid outlet pipe. The negative pressure drainage device consists of a diaphragm pump and a drainage tube. One end of the drainage tube is inserted into the bottom of the liquid dispensing barrel, and the other end is connected to the liquid inlet of the diaphragm pump via a quick connector. The liquid outlet of the diaphragm pump is connected to the liquid outlet pipe. When the diaphragm pump is started, negative pressure is formed in the drainage tube, which draws the polishing liquid in the liquid dispensing barrel into the liquid outlet pipe. Step 4: Reflux Cooling Design A cooling unit is installed in the polishing liquid recovery box, which consists of a cooling coil and a temperature sensor. The cooling coil is made of copper and arranged in a spiral shape at the bottom of the recovery box. Its two ends are connected to the external cooling water supply system through threaded connections. The surface of the cooling coil is covered with a thermally conductive silicone layer. The temperature sensor is installed on the inner wall of the recovery box, and its probe is immersed in the polishing liquid to monitor the liquid temperature in real time.

2. The method for controlling the constant temperature of a wafer polishing liquid according to claim 1, wherein The high-precision temperature sensor is a platinum resistance temperature sensor with a measurement range of 0°C to 100°C and a measurement accuracy of ±0.05°C.

3. The constant temperature control method for wafer polishing liquid according to claim 1, characterized in that The electromagnetic induction coil of the non-contact heating device has an operating frequency of 20 kHz to 30 kHz, and the surface of the coil is coated with a high-temperature resistant insulating coating with a thickness of 0.5 mm to 1 mm.

4. The method for controlling the constant temperature of a wafer polishing liquid according to claim 1, wherein The spiral diameter of the cooling coil is 10 cm to 15 cm, the coil spacing is 2 cm to 3 cm, and the total length of the coil is 5 m to 8 m.

5. The constant temperature control method for wafer polishing liquid according to claim 1, characterized in that The polishing liquid recovery box adopts a double-layer structure, the outer layer is made of stainless steel, and the inner layer is a polytetrafluoroethylene coating with a coating thickness of 0.3mm to 0.5mm.

6. A wafer polishing liquid constant temperature control system, characterized in that It includes liquid dispensing barrel, liquid outlet pipe, high-precision temperature sensor, self-circulating pipeline, diaphragm pump, drainage pipe, polishing liquid recovery tank, cooling coil and temperature sensor; A self-circulating pipeline is set inside the liquid mixing barrel. The spiral diameter of the self-circulating pipeline is 30cm, the pitch is 5cm, the barrel height is limited to 45-60cm, and the total length of the self-circulating pipeline is 67.5-90cm. It is connected to the bottom and top of the barrel through flanges; a non-contact heating device is installed on the outer wall of the self-circulating pipeline; one end of the liquid outlet pipe is connected to the outlet of the liquid mixing barrel, and the other end extends to the processing machine; a high-precision temperature sensor is installed at the outlet of the liquid outlet pipe and fixed to the inner wall of the pipe through a threaded connection; the negative pressure drainage device consists of a diaphragm pump and a drainage tube. One end of the drainage tube is inserted into the bottom of the liquid mixing barrel, and the other end is connected to the liquid inlet of the diaphragm pump through a quick connector; a cooling unit is set in the polishing liquid recovery box. The cooling unit consists of a cooling coil and a temperature sensor. The cooling coil is spirally arranged at the bottom of the recovery box and is connected to the external cooling water supply system through a threaded connection.

7. The wafer polishing liquid constant temperature control system according to claim 6, characterized in that The high-precision temperature sensor is a platinum resistance temperature sensor with a measurement range of 0°C to 100°C and a measurement accuracy of ±0.05°C.

8. The wafer polishing liquid constant temperature control system according to claim 6, characterized in that The electromagnetic induction coil of the non-contact heating device has an operating frequency of 20kHz to 30kHz, an input voltage of 220V±10%, a power density of 1.5-2.0kW / m, and a high-temperature resistant insulating coating coated on the coil surface with a coating thickness of 0.5mm to 1mm.

9. The wafer polishing liquid constant temperature control system according to claim 6, characterized in that The spiral diameter of the cooling coil is 10 cm to 15 cm, the coil spacing is 2 cm to 3 cm, and the total length of the coil is 5 m to 8 m.

10. The wafer polishing liquid constant temperature control system according to claim 6, characterized in that The polishing liquid recovery box adopts a double-layer structure, the outer layer is made of stainless steel, and the inner layer is a polytetrafluoroethylene coating with a coating thickness of 0.3mm to 0.5mm.

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