Accurate grinding fluid supply system of CMP equipment and control method of accurate grinding fluid supply system

Abstract

The invention relates to a precise grinding fluid supply system of CMP equipment and a control method thereof, and belongs to the technical field of semiconductor wafer processing, the precise grinding fluid supply system comprises the CMP equipment, a diluent tank and a stock solution tank are arranged on the outer side of the CMP equipment, static mixers are arranged between the CMP equipment and the diluent tank and between the CMP equipment and the stock solution tank, and mixed supply pipes are arranged between the static mixers and the CMP equipment. A stock solution delivery pipe is arranged between the static mixer and the stock solution tank, a stock solution delivery pump is arranged on the stock solution delivery pipe, an ultrasonic disperser communicated with the stock solution delivery pipe is arranged between the stock solution delivery pump and the static mixer, a diluent delivery pipe is arranged between the static mixer and the diluent tank, and a diluent delivery pump is arranged on the diluent delivery pipe. The device has the characteristics of compact structure, safe and reliable operation and high efficiency. The mixing uniformity and dispersity of the grinding liquid are obviously improved, the grinding particles are effectively prevented from settling, and the supply stability is ensured. And the process consistency is guaranteed through accurate temperature control. And meanwhile, convenience in cleaning and remodeling is realized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor wafer processing technology, and more specifically to a precision slurry supply system and control method for CMP equipment. Background Technology

[0002] CMP equipment is a key piece of equipment in semiconductor manufacturing to achieve ultra-precise planarization of wafer surfaces. Through the synergistic effect of chemical etching and mechanical polishing, the surface roughness of wafers is controlled at the nanometer level, providing a foundation for subsequent photolithography processes.

[0003] The chemical components in the polishing slurry soften the wafer surface, and mechanical grinding removes material, achieving nanoscale planarization. The polishing unit achieves planarization through the relative movement of the polishing head and polishing pad holding the wafer, and uses multi-zone pressure control to optimize planarization. The endpoint detection system monitors the film thickness in real time to prevent over-polishing or under-polishing. The cleaning unit removes particulate contaminants and dries the wafer.

[0004] The current CMP equipment's slurry supply system suffers from three major technical pain points, severely restricting wafer polishing yield and equipment uptime: 1. Lagging Concentration Control: Existing systems mostly adopt the "offline premixing + fixed delivery" mode. When the wafer polishing stage switches from "rough polishing" to "fine polishing", the polishing slurry tank needs to be replaced manually. The switching process takes ≥5 minutes, during which the polishing slurry concentration fluctuates within ±8%, resulting in local over-polishing or under-polishing of the wafer surface. The edge thickness difference (TTV) of 12-inch wafers often exceeds 50nm, which does not meet the TTV≤20nm requirement of advanced processes (7nm and below).

[0005] 2. Frequent pipe blockage: The nano-sized abrasive particles (such as SiO2 and Al2O3) contained in the grinding fluid are prone to sedimentation when the flow rate in the pipe is less than 0.5m / s. The existing pipes rely solely on "end-point filter", which is prone to blockage when the filter pore size is ≤5μm. It requires downtime every 72 hours for replacement, and a single maintenance takes ≥1 hour. The equipment's annual downtime for maintenance exceeds 120 hours.

[0006] 3. Temperature-induced uncontrolled effects: For every 1°C fluctuation in the polishing slurry temperature, the polishing rate changes by 5%-8%. The existing system does not have a closed-loop temperature control and relies solely on the ambient temperature of the workshop (23±2°C), resulting in a polishing rate difference of more than 10% for the same batch of wafers. This necessitates an additional "re-polishing" process, extending the process time. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a precision grinding slurry supply system and its control method for CMP equipment. This system features a compact structure, safe and reliable operation, and high efficiency. It significantly improves the mixing uniformity and dispersibility of the grinding slurry, effectively prevents grinding particle sedimentation, and ensures stable supply. Precise temperature control guarantees process consistency. Simultaneously, the efficient backwashing and anti-clogging design facilitates cleaning and changeover.

[0008] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions: A precision slurry supply system for CMP equipment includes a CMP device. A diluent tank and a stock solution tank are located on the outside of the CMP device. Static mixers are located between the CMP device and the diluent tank, and between the CMP device and the stock solution tank. A mixing supply pipe is located between the static mixer and the CMP device. A stock solution delivery pipe is located between the static mixer and the stock solution tank. A stock solution delivery pump is installed on the stock solution delivery pipe. An ultrasonic disperser connected to the stock solution delivery pipe is located between the stock solution delivery pump and the static mixer. A diluent delivery pipe is located between the static mixer and the diluent tank, and a diluent delivery pump is installed on the diluent delivery pipe.

[0009] Preferably, an inlet pump is provided between the mixing supply pipe and the static mixer, a mixing output pipe is provided between the inlet pump and the static mixer, a platinum resistance temperature sensor is provided on the mixing output pipe, a flexible heating tape that is in circuit connection with the platinum resistance temperature sensor is wrapped around the outer wall of the mixing output pipe, and a cooling fan is provided on the outside of the mixing output pipe.

[0010] Preferably, a backflushing pipe is provided between the mixing supply pipe and the diluent tank, and valves are provided on the backflushing pipe and between the raw material transfer pump and the raw material tank. A level gauge is provided on the diluent tank.

[0011] The mixing supply pipe and subsequent pipelines are backflushed through the backflushing pipe to remove residual grinding fluid and prevent pipeline blockage or cross-contamination.

[0012] Preferably, a high-frequency micro-vibrator is provided outside the mixing supply pipe, and a high-frequency micro-vibration belt is provided between the high-frequency micro-vibrator and the mixing supply pipe, which is isolated from the silicone pad on the outer wall of the mixing supply pipe.

[0013] A control method for a precision grinding slurry supply system includes the following steps: Step 1: Liquid supply and pretreatment.

[0014] S1 Stock Solution Delivery and Ultrasonic Dispersion: Start the stock solution delivery pump to draw the stock solution from the stock solution tank. The stock solution flows through the ultrasonic disperser, where the ultrasonic cavitation effect breaks up any agglomerated particles that may be present in the stock solution, ensuring the initial dispersion of the stock solution.

[0015] S2 Diluent Delivery: Simultaneously start the diluent delivery pump to draw diluent from the diluent tank. The liquid level is monitored in real time via a level gauge on the diluent tank to prevent the pump from running dry.

[0016] Step 2: Precise mixing and closed-loop feedback control.

[0017] S3 Static Mixing: The pretreated stock solution and diluent are fed into the static mixer, where the fluids undergo preliminary physical mixing under the cutting and recombination action of the internal units.

[0018] S4 Concentration Detection and Proportion Adjustment: The mixed fluid enters the mixing output pipe and flows through the series-connected optical concentration sensor. The optical concentration sensor detects the concentration data of the mixture in real time and transmits the signal to the control system. Based on the deviation between the set value and the measured value, the system automatically adjusts the opening of the electromagnetic proportional valves on the original liquid delivery pipe and the diluent delivery pipe (2) to dynamically correct the flow ratio of the two liquids until the concentration reaches the required accuracy.

[0019] Step 3: Temperature control, constant flow conveying and feeding.

[0020] S5 Temperature Detection and Control: The mixed liquid flows through the platinum resistance temperature sensor to monitor the fluid temperature in real time; when the temperature is lower than the set value of 24.5℃, the flexible heating strip wrapped around the pipe wall starts heating; when the temperature is higher than the set value of 25.5℃, the cooling fan located on the outside starts air cooling.

[0021] S6 Final Pressurization and Supply: The mixture is pressurized by the inlet pump and then precisely and stably delivered to the grinding table of the CMP equipment through the mixing supply pipe for operation.

[0022] Preferably, as the fluid travels through the mixing supply pipe to the CMP equipment, a high-frequency micro-vibrator is activated, and the vibration is transmitted to the pipe via a high-frequency micro-vibration belt and a silicone pad.

[0023] As a preferred method, when the system needs to be cleaned or the type of grinding fluid is changed, the relevant valves are closed, the valves on the backflushing pipeline are opened, the cleaning fluid in the dilution tank is used, the inlet pump is started in reverse, and the mixing supply pipeline and subsequent pipelines are backflushed through the backflushing pipeline to remove residual grinding fluid and prevent pipeline blockage or cross-contamination.

[0024] The present invention can achieve the following effects: This invention provides a precision slurry supply system and control method for CMP equipment. Compared with existing technologies, it features a compact structure, safe and reliable operation, and high efficiency. It significantly improves the mixing uniformity and dispersibility of the slurry, effectively prevents grinding particle sedimentation, and ensures stable supply. Precise temperature control guarantees process consistency. Simultaneously, the efficient backwashing and anti-clogging design facilitates cleaning and changeover.

[0025] (1) Significantly improves the uniformity and dispersibility of the grinding slurry. Ultrasonic dispersion pretreatment: By setting an ultrasonic disperser on the raw liquid delivery pipeline, the ultrasonic cavitation effect is used to break up any agglomerated particles that may exist in the raw liquid before mixing, ensuring the initial dispersibility of the raw liquid and solving the particle agglomeration problem from the source.

[0026] Static mixing and dynamic adjustment: A closed-loop feedback control system combining a static mixer with an optical concentration sensor and an electromagnetic proportional valve enables real-time monitoring and dynamic correction of the stock solution to diluent ratio. Compared to open-loop control, this significantly improves the accuracy and consistency of the mixed solution concentration, avoiding instability in the CMP process caused by ratio fluctuations.

[0027] (2) Effectively prevents grinding particles from settling and ensures supply stability. High-frequency micro-vibration technology: A high-frequency micro-vibrator and a high-frequency micro-vibration belt are installed on the final mixing supply pipe, and the micro-vibration is transmitted in an isolated manner through a silicone pad. This design continuously applies micro-vibration in the final stage of liquid delivery to the grinding table, effectively disrupting the gravity settling tendency of the particles, preventing concentration gradients or sedimentation in the pipeline, and ensuring that the grinding fluid entering the CMP equipment is always a uniform suspension.

[0028] (3) Precise temperature control ensures process consistency. Constant temperature and pressure supply: Real-time monitoring via a platinum resistance temperature sensor, combined with the coordinated operation of a flexible heating belt and a cooling fan, precisely controls the temperature of the mixture within a narrow range of 24.5℃ to 25.5℃. Small temperature fluctuations can significantly affect the chemical reaction rate and material removal rate. This system eliminates the impact of ambient temperature changes on the process, thereby improving the repeatability and yield of CMP processing.

[0029] (4) Highly efficient backwashing and anti-clogging design.

[0030] Convenient cleaning and changeover: A specially designed backflushing pipeline utilizes the reverse flow of the inlet pump in conjunction with the diluent to backflush the mixing supply pipe and subsequent pipelines. This not only facilitates routine maintenance but also effectively removes residues when switching grinding fluid types, preventing cross-contamination and pipeline blockage, thereby improving production efficiency and equipment uptime.

[0031] (5) Compact structure and high degree of automation. System integration: The functions of pretreatment, mixing, temperature control, micro-vibration, and conveying are integrated into a modular system, and the sensors, pumps and valves are connected by circuits to achieve automatic control.

[0032] Safe and reliable operation: The liquid level gauge prevents the pump from running dry, and multiple sensor feedbacks ensure that all parameters (concentration, temperature, flow rate) are within the optimal range, reducing errors caused by manual intervention and lowering the workload of operators. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of the hybrid output tube of the present invention.

[0035] In the diagram: 1. Diluent tank; 2. Diluent delivery pipe; 3. Valve; 4. Diluent delivery pump; 5. Electromagnetic proportional valve; 6. Static mixer; 7. Backwash pipe; 8. Inlet pump; 9. CMP equipment; 10. Mixing supply pipe; 11. High-frequency micro-vibration belt; 12. High-frequency micro-vibrator; 13. Cooling fan; 14. Mixing output pipe; 15. Raw material delivery pipe; 16. Ultrasonic disperser; 17. Raw material delivery pump; 18. Raw material tank; 19. Level gauge; 20. Flexible heating belt; 21. Platinum resistance temperature sensor; 22. Optical concentration sensor. Detailed Implementation

[0036] The technical solution of the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0037] Example: Figure 1 and Figure 2As shown, a precision slurry supply system for a CMP (Continuous Metallurgical Processing) device includes a CMP device 9. A diluent tank 1 and a stock solution tank 18 are located outside the CMP device 9. Static mixers 6 are installed between the CMP device 9 and the diluent tank 1, and between the CMP device 9 and the stock solution tank 18. A mixing supply pipe 10 is installed between the static mixer 6 and the CMP device 9. A high-frequency micro-vibrator 12 is installed outside the mixing supply pipe 10. A high-frequency micro-vibration belt 11, which is isolated from the silicone pad on the outer wall of the mixing supply pipe 10, is installed between the high-frequency micro-vibrator 12 and the mixing supply pipe 10. A backwash pipe 7 is installed between the mixing supply pipe 10 and the diluent tank 1. Valves 3 are installed on the backwash pipe 7 and between the stock solution delivery pump 17 and the stock solution tank 18. A level gauge 19 is installed on the diluent tank 1. A liquid inlet pump 8 is provided between the mixing supply pipe 10 and the static mixer 6. A mixing output pipe 14 is provided between the liquid inlet pump 8 and the static mixer 6. A platinum resistance temperature sensor 21 is provided on the mixing output pipe 14. A flexible heating tape 20, which is electrically connected to the platinum resistance temperature sensor 21, is wound around the outer wall of the mixing output pipe 14. A cooling fan 13 is provided on the outside of the mixing output pipe 14. An optical concentration sensor 22, which is connected in series with the platinum resistance temperature sensor 21, is also provided on the mixing output pipe 14. Electromagnetic proportional valves 5, which are electrically connected to the optical concentration sensor 22, are provided on both the diluent delivery pipe 2 and the stock solution delivery pipe 15. A stock solution delivery pipe 15 is provided between the static mixer 6 and the stock solution tank 18. A stock solution delivery pump 17 is provided on the stock solution delivery pipe 15. An ultrasonic disperser 16, which is connected to the stock solution delivery pipe 15, is provided between the stock solution delivery pump 17 and the static mixer 6. A diluent delivery pipe 2 is provided between the static mixer 6 and the diluent tank 1. A diluent delivery pump 4 is provided on the diluent delivery pipe 2.

[0038] A control method for a precision slurry supply system in a CMP (Chemical Metallurgy) equipment includes the following steps: Step 1: Liquid supply and pretreatment.

[0039] S1. Stock Solution Delivery and Ultrasonic Dispersion: Start the stock solution delivery pump 17 to draw the stock solution from the stock solution tank 18. The stock solution flows through the ultrasonic disperser 16, where the ultrasonic cavitation effect breaks up any agglomerated particles that may be present in the stock solution, ensuring the initial dispersion of the stock solution.

[0040] S2 Diluent Delivery: Simultaneously start the diluent delivery pump 4 to draw diluent from the diluent tank 1. The liquid level is monitored in real time by the level gauge 19 on the diluent tank to prevent the pump from running dry.

[0041] Step 2: Precise mixing and closed-loop feedback control.

[0042] S3 Static Mixing: The pretreated stock solution and diluent are fed into the static mixer 6. The fluids undergo preliminary physical mixing under the cutting and recombination action of the internal units of the static mixer.

[0043] S4 Concentration Detection and Proportion Adjustment: The mixed fluid enters the mixing output pipe 14 and flows through the series-connected optical concentration sensor 22. The optical concentration sensor 22 detects the concentration data of the mixture in real time and transmits the signal to the control system. Based on the deviation between the set value and the measured value, the system automatically adjusts the opening of the electromagnetic proportional valve 5 on the original liquid delivery pipe 12 and the diluent delivery pipe 2, dynamically correcting the flow ratio of the two liquids until the concentration reaches the precise requirement.

[0044] Step 3: Temperature control, constant flow conveying and feeding.

[0045] S5 Temperature Detection and Control: The mixed liquid flows through the platinum resistance temperature sensor 21, which monitors the fluid temperature in real time. When the temperature is lower than the set value of 24.5℃, the flexible heating belt 20 wrapped around the pipe wall starts heating. When the temperature is higher than the set value of 25.5℃, the flexible heating belt 20 stops heating, and the cooling fan 13 located on the outside starts air cooling.

[0046] As the fluid travels through the mixing supply pipe 10 to the CMP equipment, the high-frequency microvibrator 12 is activated, and the vibration is transmitted to the pipe through the high-frequency microvibration belt 11 and the silicone pad.

[0047] S6 Final pressurization and supply: The mixture flows through the inlet pump 8 for final pressurization, and is then precisely and stably delivered to the grinding table of the CMP equipment 9 for operation via the mixing supply pipe 10.

[0048] When the system needs to be cleaned or the type of grinding fluid needs to be changed, close the relevant valves, open valve 3 on the backwash line, use the cleaning fluid in the dilution tank, start the inlet pump 8 to reverse, and backwash the mixing supply pipe 10 and subsequent pipelines through the backwash pipe 7 to remove residual grinding fluid and prevent pipeline blockage or cross-contamination.

[0049] In summary, the CMP equipment's precision grinding slurry supply system and its control method are characterized by compact structure, safe and reliable operation, and high efficiency. It significantly improves the mixing uniformity and dispersibility of the grinding slurry, effectively prevents grinding particle sedimentation, and ensures stable supply. Precise temperature control guarantees process consistency. Simultaneously, the efficient backwashing and anti-clogging design facilitates cleaning and changeover.

[0050] Yield improvement: Through concentration-temperature coordinated control, the TTV of 12-inch wafers has been reduced from the current 50nm to below 15nm, and the polishing yield has been increased from 82% to 97%; the wafer scratch rate has been reduced from 0.8% to below 0.1%, avoiding wafer scrap due to scratches.

[0051] Efficiency optimization: The pipeline blockage cycle has been extended from 72 hours to 320 hours, the annual equipment downtime for maintenance has been reduced from 120 hours to 28 hours, and the uptime rate has been increased to over 98%; the grinding slurry concentration can be switched without stopping the machine, the polishing time for a single batch of wafers has been reduced by 5 minutes, and 20 more wafers can be processed per day.

[0052] Cost reduction: The ultrasonic dispersion and backwashing design increases the utilization rate of grinding fluid by 15%, reducing the annual purchase cost of grinding fluid by approximately 200,000 yuan; the maintenance frequency is reduced, saving approximately 50,000 yuan in maintenance consumable costs annually.

[0053] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A precision slurry supply system for a CMP (Chemical Metallurgy) device, comprising a CMP device (9), characterized in that: The CMP equipment (9) is provided with a diluent tank (1) and a stock solution tank (18) on the outside. A static mixer (6) is provided between the CMP equipment (9) and the diluent tank (1) and between the CMP equipment (9) and the stock solution tank (18). A mixing supply pipe (10) is provided between the static mixer (6) and the CMP equipment (9). A stock solution delivery pipe (15) is provided between the static mixer (6) and the stock solution tank (18). A stock solution delivery pump (17) is provided on the stock solution delivery pipe (15). An ultrasonic disperser (16) connected to the stock solution delivery pipe (15) is provided between the stock solution delivery pump (17) and the static mixer (6). A diluent delivery pipe (2) is provided between the static mixer (6) and the diluent tank (1). A diluent delivery pump (4) is provided on the diluent delivery pipe (2).

2. The precision slurry supply system for CMP equipment according to claim 1, characterized in that: A liquid inlet pump (8) is provided between the mixing supply pipe (10) and the static mixer (6). A mixing output pipe (14) is provided between the liquid inlet pump (8) and the static mixer (6). A platinum resistance temperature sensor (21) is provided on the mixing output pipe (14). A flexible heating tape (20) connected to the circuit of the platinum resistance temperature sensor (21) is wrapped around the outer wall of the mixing output pipe (14). A cooling fan (13) is provided on the outside of the mixing output pipe (14).

3. The precision slurry supply system for CMP equipment according to claim 2, characterized in that: The mixing output tube (14) is also equipped with an optical concentration sensor (22) connected in series with the platinum resistance temperature sensor (21). The diluent delivery tube (2) and the original liquid delivery tube (15) are both equipped with electromagnetic proportional valves (5) that are connected in circuit with the optical concentration sensor (22).

4. The precision slurry supply system for CMP equipment according to claim 1, characterized in that: A backwash pipe (7) is provided between the mixing supply pipe (10) and the diluent tank (1). Valves (3) are provided on the backwash pipe (7) and between the raw liquid transfer pump (17) and the raw liquid tank (18). A level gauge (19) is provided on the diluent tank (1).

5. The precision slurry supply system for CMP equipment according to claim 1, characterized in that: The mixing supply pipe (10) is provided with a high-frequency micro-vibrator (12), and a high-frequency micro-vibration belt (11) is provided between the high-frequency micro-vibrator (12) and the mixing supply pipe (10) and is wound in a way that isolates it from the silicone pad on the outer wall of the mixing supply pipe (10).

6. A control method for a precision slurry supply system for CMP equipment according to claim 3, characterized in that... The following steps are included: Step 1: Liquid supply and pretreatment; S1 Raw material delivery and ultrasonic dispersion: Start the raw material delivery pump (17) to extract the raw material from the raw material tank (18); the raw material flows through the ultrasonic disperser (16) and uses the ultrasonic cavitation effect to break up any agglomerated particles in the raw material to ensure the initial dispersion of the raw material. S2 Diluent Delivery: Simultaneously start the diluent delivery pump (4) to extract the diluent from the diluent tank (1); monitor the liquid level in real time through the level gauge (19) on the diluent tank to prevent the pump from running dry; Step 2: Precise mixing and closed-loop feedback control; S3 Static Mixing: The pretreated stock solution and diluent are fed into the static mixer (6). The fluids undergo preliminary physical mixing under the cutting and recombination action of the internal units of the static mixer. S4 Concentration Detection and Proportion Adjustment: The mixed fluid enters the mixing output pipe (14) and flows through the series-connected optical concentration sensor (22); the optical concentration sensor (22) detects the concentration data of the mixed liquid in real time and transmits the signal to the control system; the system automatically adjusts the opening of the electromagnetic proportional valve (5) on the original liquid delivery pipe (12) and the diluent delivery pipe (2) according to the deviation between the set value and the measured value, and dynamically corrects the flow ratio of the two liquids until the concentration reaches the accurate requirement; Step 3: Temperature control, constant flow conveying and feeding; S5 Temperature detection and temperature control: The mixed liquid flows through the platinum resistance temperature sensor (21) to monitor the fluid temperature in real time; when the temperature is lower than the set value of 24.5℃, the flexible heating belt (20) wrapped around the pipe wall starts heating; when the temperature is higher than the set value of 25.5℃, the flexible heating belt (20) stops heating, and the cooling fan (13) located on the outside starts air cooling. S6 Final pressurization and supply: The mixture is pressurized by the inlet pump (8) and then accurately and stably delivered to the grinding table of the CMP equipment (9) through the mixing supply pipe (10) for operation.

7. The control method for the precision supply system of polishing slurry in CMP equipment according to claim 6, characterized in that: As the fluid travels through the mixing supply pipe (10) to the CMP equipment, a high-frequency microvibrator (12) is activated, and vibrations are transmitted to the pipe via a high-frequency microvibration belt (11) and a silicone pad.

8. The control method for the precision supply system of polishing slurry in CMP equipment according to claim 6, characterized in that: When the system needs to be cleaned or the type of grinding fluid is changed, close the relevant valves, open the valve (3) on the backwash line, use the cleaning fluid in the dilution tank, start the inlet pump (8) to reverse, and backwash the mixing supply pipe (10) and subsequent pipelines through the backwash pipe (7) to remove residual grinding fluid and prevent pipeline blockage or cross-contamination.

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