Anti-backflow tail gas treatment device for vertical furnace

Abstract

The utility model provides a kind of for vertical furnace's anti backwash tail gas treatment device, including jar body, the jar body top is equipped with air inlet, bottom is equipped with air outlet and liquid discharge port;Air inlet pipeline, the air inlet pipeline is connected with the air inlet, and the air inlet pipeline is inclined downward setting;A check valve is set on the air inlet pipeline;B check valve is set at the air outlet.The utility model effectively solves the problem of low reliability of single anti backwash structure in the prior art, cannot meet the needs of two-way pressure adaptation of positive pressure backflushing and negative pressure backwash protection, significantly improves the operating stability and safety of tail gas treatment device under high-temperature corrosive conditions, and ensures the cleanliness of vertical furnace process environment and wafer processing yield.

Description

Technical Field

[0001] This utility model relates to an anti-backflow tail gas treatment device for a vertical furnace. Background Technology

[0002] Vertical furnaces are key process equipment in semiconductor manufacturing, widely used in high-temperature processes such as oxidation, diffusion, and chemical vapor deposition. These processes generate high-temperature exhaust gases containing corrosive gases (such as HCl, Cl2, and NF3) and byproduct particles, which must be promptly discharged through exhaust pipes to a central waste gas treatment system for purification. However, in actual operation, especially during process completion, gas switching, vacuum pump start-up and shutdown, or sudden power outages, instantaneous negative pressure or pressure fluctuations can easily occur in the exhaust pipes. Without effective protective measures, moisture, acid mist, and even incompletely treated harmful gases from the central waste gas treatment system may backflow into the high-temperature furnace tube, causing a series of serious problems: firstly, condensate droplets contacting high-temperature quartz components (such as furnace tubes and crystal boats) can lead to thermal stress cracking; secondly, backflow contaminants can adhere to the wafer surface, causing metal contamination, particle defects, and reduced product yield; more seriously, backflow of flammable or reactive gases may even cause safety incidents. Existing exhaust gas treatment devices mostly employ a single backflow prevention structure, such as a common one-way valve or water seal structure. However, these generally suffer from the following shortcomings: First, they have low reliability and are prone to failure under high-temperature and corrosive conditions; second, they cannot simultaneously meet the dual pressure adaptation requirements of overpressure relief and negative pressure backflow protection within the furnace; and third, they lack effective filtration of particulate matter in the exhaust gas and recovery of condensate, easily leading to pipeline blockage and equipment corrosion. Therefore, there is an urgent need for a reliable exhaust gas treatment device with dual pressure protection to meet the stringent requirements of advanced processes for cleanliness, safety, and equipment stability. Utility Model Content

[0003] This invention provides a backflow prevention tail gas treatment device for vertical furnaces, which can effectively solve the above-mentioned problems.

[0004] This utility model is implemented as follows:

[0005] A backflow prevention exhaust gas treatment device for a vertical furnace, comprising:

[0006] The tank body has an air inlet at the top and an air outlet and a liquid outlet at the bottom.

[0007] An air intake pipe is connected to the air intake port, and the air intake pipe is inclined downwards;

[0008] A one-way valve is installed on the air intake pipe;

[0009] B. One-way valve, located at the air outlet;

[0010] Specifically, the A check valve closes when the pressure inside the tank exceeds a first preset value, and the B check valve closes when the pressure inside the tank is lower than a second preset value.

[0011] The beneficial effects of this utility model are:

[0012] (1) This utility model realizes a two-way pressure adaptive protection function by setting an A one-way valve on the air inlet pipe and a B one-way valve at the air outlet, combined with pressure preset value control. When the pressure in the tank exceeds the first preset value, the A one-way valve automatically closes to prevent the high-pressure airflow from backflowing back into the vertical furnace and damaging the furnace process environment. When the pressure in the tank is lower than the second preset value, the B one-way valve automatically closes to block the downstream moisture or acid mist from flowing back into the tank and the vertical furnace. This effectively solves the problem that the single anti-backflow structure in the prior art has low reliability and cannot take into account the two-way pressure adaptation requirements of positive pressure backflow and negative pressure backflow protection. It significantly improves the operation stability and safety of the tail gas treatment device under high temperature and corrosive conditions, and ensures the cleanliness of the vertical furnace process environment and the wafer processing yield. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is the front view of this utility model.

[0015] Figure 2 This is a schematic diagram of the exhaust gas treatment component of this utility model. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model.

[0017] In the description of this utility model, the terms "first" and "second" 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, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0018] Reference Figure 1-2 As shown, a backflow prevention tail gas treatment device for a vertical furnace includes...

[0019] The tank body 700 has an air inlet 704 at the top and an air outlet 720 and a drain outlet 716 at the bottom; an air inlet pipe 702 is connected to the air inlet 704 and is inclined downward; an A one-way valve 706 is installed on the air inlet pipe 702; a B one-way valve 718 is installed at the air outlet 720; wherein, the A one-way valve 706 closes when the pressure inside the tank body 700 exceeds a first preset value, and the B one-way valve 718 closes when the pressure inside the tank body 700 is lower than a second preset value. The tank 700 has a conical bottom with a drain port 716 located at the lowest point of the cone. A shut-off valve 714 is installed at the drain port 716. The cone angle is moderate, allowing condensate and deposited solid particles to naturally slide to the lowest point. The tank 700 also includes a pressure relief valve that opens when the pressure inside the tank exceeds a third preset value. The pressure relief valve is installed on the top or side wall of the tank 700 as a final safety protection device. When the pressure inside the tank rises sharply due to abnormal conditions (such as exhaust gas deflagration or pipeline blockage) and exceeds the third preset value (e.g., +5 kPa), the pressure relief valve automatically opens to quickly release the overpressure gas, preventing the tank from rupturing or exploding.

[0020] Specifically, the tank 700, as the main container for exhaust gas treatment, is made of high-temperature and corrosion-resistant materials (such as 316L stainless steel) and has an overall vertical cylindrical structure. The air inlet 704 is located on the top side of the tank 700 to facilitate the exhaust gas entering the tank from top to bottom. The air outlet 720 is located on the bottom side of the tank 700 and connects to the subsequent central exhaust gas treatment system. The liquid drain 716 is located at the bottom of the tank 700 and is used to periodically discharge condensate and deposited impurities. The bottom of the tank 700 is designed with a conical structure to facilitate the natural collection of liquid and solid particles to the lowest point, thereby improving emission efficiency.

[0021] Furthermore, the air inlet pipe 702 connects the exhaust port of the vertical furnace to the air inlet 704 of the tank 700, and adopts an inclined downward arrangement (at a certain angle relative to the horizontal plane), so that the exhaust gas enters the interior of the tank 700 at a certain angle, avoiding the high-temperature exhaust gas from directly impacting the internal structure and liquid surface of the tank vertically, reducing the scouring and vibration of the internal components by the airflow, reducing the impact of the airflow, extending the service life of the equipment, and preventing the condensate from flowing back into the furnace body.

[0022] Based on the above, check valve A 706 is installed on the inlet pipe 702 to control the direction of exhaust gas entering the tank, allowing exhaust gas to flow only from the vertical furnace to the tank 700; check valve B 718 is installed at the outlet 720 to control the direction of exhaust gas discharge, allowing exhaust gas to flow only from the tank 700 to the central waste gas treatment system. When the internal pressure of the tank 700 rises abnormally (such as in-furnace deflagration or airflow blockage) and exceeds the first preset value (e.g., +3kPa), check valve A 706 automatically closes to prevent high-pressure airflow from backflowing into the vertical furnace and to protect the process environment inside the furnace; when the internal pressure of the tank 700 drops abnormally (such as vacuum pump shutdown or negative pressure in the exhaust pipe) and falls below the second preset value (e.g., -2kPa), check valve B 718 automatically closes to prevent moisture and acid mist from the central waste gas treatment system from flowing back into the tank and the vertical furnace.

[0023] It also includes a filter assembly 710 disposed inside the tank 700, the filter assembly 710 including a detachable metal filter screen and a filter screen fixing frame, the filter screen fixing frame being connected to the inner wall of the tank 700 by a snap fastener; it also includes a buffer assembly 708 disposed inside the tank 700, the buffer assembly 708 including multiple guide plates arranged in a spiral shape in the middle of the tank 700; it also includes a condensate recovery assembly, the condensate recovery assembly including: a condensate pipe 712, wound around the outside of the tank 700 to form a condensate jacket; a condensate collection tank disposed at the bottom of the tank 700; and a recovery tank connected to the condensate collection tank via a pipe, the pipe being equipped with a solenoid valve.

[0024] The filter assembly 710 is located inside the air inlet 704, at the initial position where the exhaust gas enters the tank. The metal filter screen is made of 50-100 mesh stainless steel wire mesh, which can effectively intercept solid particles (such as reaction byproducts, dust, etc.) in the exhaust gas. The filter screen fixing frame is detachably connected to the inner wall of the tank through a snap-fit ​​structure, which is convenient for periodic removal for cleaning or replacement. The buffer assembly 708 includes multiple guide plates, which are arranged in a spiral shape along the inner wall of the tank 700 to form a meandering airflow channel. When the exhaust gas enters the tank, it is forced to flow along the spiral path, prolonging its residence time in the tank, reducing the airflow velocity, absorbing pressure fluctuations, and promoting particulate matter sedimentation and condensate precipitation.

[0025] Furthermore, the condensate pipe 712 is evenly wound around the outer wall of the tank 700 and connected to the cooling water circulation system. Through heat exchange, the temperature inside the tank is reduced, causing condensable components in the exhaust gas (such as water vapor and acid mist) to liquefy into liquid. The condensate flows down the tank wall and collects in the condensate collection tank (not shown in the figure) at the bottom of the tank 700. When the liquid level sensor in the collection tank detects that the liquid level has reached the set value, the control system automatically opens the solenoid valve on the pipeline to discharge the condensate into the recovery tank for centralized treatment or recycling.

[0026] The inner wall of tank 700 is coated with a corrosion-resistant coating, which is a ceramic-based composite coating. An inspection port is located on the top of tank 700. The inner wall of tank 700 is coated with a ceramic-based composite coating (such as Al2O3-TiO2), which can withstand temperatures above 800℃ and is resistant to strong acids, strong alkalis, and high-temperature corrosive media. It bonds tightly to the 316L stainless steel substrate and is not easily peeled off. The inspection port on the top of tank 700 allows operators to easily enter the tank for cleaning, filter replacement, or inspection of internal components.

[0027] It should be noted that a set of the above-mentioned exhaust gas treatment devices is symmetrically arranged at both ends of the vertical furnace (such as the upper and lower parts, or the left and right sides), and connected to different exhaust ports of the furnace body respectively. This symmetrical layout can realize bidirectional coordinated collection of exhaust gas from the entire furnace body, balance the pressure field distribution inside the furnace, avoid local airflow turbulence and the formation of eddies, and at the same time, the two sets of devices form a redundancy guarantee. When one set is under maintenance, the other set can maintain basic treatment functions to ensure production continuity.

[0028] Furthermore, the first exhaust gas treatment device is connected to the top exhaust port of the vertical furnace, which is connected to the top of the inner pipe 40, and is used to collect high-temperature exhaust gas in the rising airflow; the second exhaust gas treatment device is connected to the bottom exhaust port of the vertical furnace, which is located at the lower part of the outer pipe 30 near the base 10, and is used to collect the descending airflow and the exhaust gas accumulated in the bottom area (the connection position is not limited, and the above connection method is only one embodiment of this case). The air inlet pipes 702 of the two sets of exhaust gas treatment devices are led out from the top or bottom of the furnace body, respectively, using 316L stainless steel pipes with a diameter of DN50~DN100. The inner wall is polished to reduce airflow resistance. Each set of devices is equipped with a manual isolation valve on the air inlet pipe 702, which facilitates the cutoff of the gas source when a single set of devices is under maintenance, without affecting the normal operation of the other set of devices. The two sets of devices operate simultaneously, each treating about 50% of the exhaust gas flow, realizing bidirectional coordinated collection of exhaust gas throughout the furnace body, balancing the pressure field distribution inside the furnace, and avoiding the formation of eddies due to local airflow turbulence.

[0029] A vertical furnace includes an outer tube 30, which is closed at the top and open at the bottom; an inner tube 40, which is disposed inside the outer tube 30 and is open at both the top and bottom; a crystal boat 50, which is disposed inside the inner tube 40 and is used to carry a wafer 60; a base 10, which is used to support the crystal boat 50 and close the open end of the outer tube 30; and a drive assembly 20, which is disposed below the base 10 and is used to drive the base 10 and the crystal boat 50 to lift, lower, and rotate.

[0030] It should be noted that this case also includes a control system (PLC), which serves as the core control unit. It is electrically connected to pressure sensors, flow sensors, and level sensors located in the air intake pipe 702, tank 700, and condensate collection tank. Through the linkage control of the solenoid valves at A check valve 706, B check valve 718, pressure relief valve, and drain port 716, it realizes the automated operation of the exhaust gas treatment device and bidirectional pressure adaptive protection. Under normal exhaust conditions, when the pressure inside the tank 700 is maintained within the normal range of -2kPa to +3kPa, the PLC controls both check valves A 706 and B 718 to remain open. This allows the exhaust gas generated by the vertical furnace to enter the tank 700 at an angle through the inlet pipe 702. The gas then passes through the filter assembly 710 to intercept particulate matter, the buffer assembly 708 to extend the residence time and absorb pressure fluctuations, and the condensation jacket formed by the condensate pipe 712 to cool and precipitate condensate before being discharged through the outlet 720 to the central exhaust gas treatment system. When the pressure sensor on the tank 700 detects that the pressure inside the tank exceeds the first preset value of +3kPa, the PLC determines this as an abnormal positive pressure backflow condition and immediately sends a closing command to check valve A 706 on the inlet pipe 702 to prevent high-pressure gas from flowing back into the vertical furnace. The process environment inside the furnace is disrupted. At the same time, the B check valve 718 located at the outlet 720 remains open to ensure that the pressure inside the tank 700 continues to be released. If the pressure continues to rise above the third preset value of +5kPa, the PLC will immediately open the pressure relief valve located on the top or side wall of the tank 700 to quickly discharge the overpressure gas to a safe area. The pressure relief valve will automatically close after the pressure drops below +2kPa. When the pressure sensor located on the tank 700 detects that the pressure inside the tank 700 is lower than the second preset value of -2kPa, the PLC determines that it is an abnormal negative pressure backflow condition and immediately sends a closing command to the B check valve 718 located at the outlet 720 to block the backflow of moisture or acid mist from the central waste gas treatment system to the tank 700 and the vertical furnace. At the same time, the A check valve 706 located on the inlet pipe 702 remains in standby state. In addition, a liquid level sensor installed in the condensate collection tank at the bottom of tank 700 monitors the liquid level changes in real time. When the liquid level rises to the high liquid level set value, the PLC automatically opens the solenoid valve installed on the pipeline at the drain port 716, discharging the condensate through the drain port 716 to the recovery tank for centralized treatment or recycling. When the liquid level drops to the low liquid level set value, the PLC automatically closes the solenoid valve, completing one drainage cycle. The entire control process is realized through the touch screen, which realizes the real-time display of operating parameters, alarm information prompts, and the visualization setting and modification of parameters such as pressure threshold and liquid level threshold, ensuring the flexible adaptation and safe and stable operation of the system under different process conditions.

[0031] To more clearly illustrate the basis for setting the pressure preset values ​​mentioned above, please refer to the chart below:

[0032]

[0033] Different settings under different working conditions

[0034]

[0035] Working principle:

[0036] During normal operation of the vertical furnace, the exhaust gas treatment device is in standby or continuous exhaust mode. When the exhaust gas generated by the vertical furnace enters the tank 700 through the inlet pipe 702, since both one-way valves A 706 and B 718 are open, the exhaust gas can smoothly pass through the inlet 704 into the tank 700. The exhaust gas entering the tank 700 first passes through the filter assembly 710, where the metal filter screen intercepts solid particles, preventing particles from entering downstream pipes or abrading the one-way valve sealing surfaces. Subsequently, the exhaust gas enters the buffer assembly 708 area, where it flows along a spiral path under the guidance of the spirally arranged guide plates, extending the residence time of the exhaust gas in the tank 700, effectively absorbing and buffering pressure fluctuations caused by process switching or pump start-up and shutdown, while promoting further sedimentation of particles in the exhaust gas. Then, the exhaust gas flows through the condensate pipe 712 wrapped around the outside of the tank 700. In the condensation jacket area, the exhaust gas temperature is reduced through cooling water circulation and heat exchange, causing condensable components in the exhaust gas (such as water vapor and acid mist) to liquefy into condensate. The condensate flows down the tank wall and collects in the condensate collection tank at the bottom of the tank 700. When the liquid level sensor detects that the liquid level has reached the set value, the control system automatically opens the solenoid valve at the drain port 716 to discharge the condensate into the recovery tank for centralized treatment or recycling. After filtration, buffering, and condensation, the exhaust gas is finally discharged through the outlet 720 and enters the central exhaust gas treatment system for further purification. Throughout the entire exhaust gas treatment process, the pressure sensor installed on the tank 700 monitors the pressure changes inside the tank 700 in real time and transmits the pressure signal to the control system in real time. When the pressure inside the tank 700 exceeds the first preset value (e.g., +3kPa), the control system determines it to be an abnormal positive pressure condition (e.g., in-furnace deflagration, downstream pipeline blockage, etc.) and immediately sends a closing command to the A check valve 706 located on the air inlet pipe 702 to cut off the channel for exhaust gas to enter the tank 700 and prevent high-pressure airflow from rushing back into the vertical furnace and damaging the furnace process environment; at the same time, the B check valve 718 located at the air outlet 720 remains open to ensure that the pressure inside the tank 700 continues to be released outward.If the pressure continues to rise above the third preset value (e.g., +5kPa), the control system will immediately open the pressure relief valve on the tank 700 to quickly discharge the overpressure gas to a safe area. After the pressure drops back to a safe range, the pressure relief valve will automatically close. When the pressure inside the tank 700 is detected to be lower than the second preset value (e.g., -2kPa), the control system determines it to be an abnormal negative pressure condition (e.g., vacuum pump shutdown, negative pressure in the exhaust pipe, etc.) and immediately sends a closing command to the B check valve 718 located at the outlet 720 to prevent the backflow of moisture, acid mist, or incompletely treated harmful gases from the central exhaust gas treatment system to the tank 700 and the vertical furnace. At the same time, the A check valve 706 located on the inlet pipe 702 remains in standby mode. Through the linkage control of the A check valve 706 and the B check valve 718, bidirectional pressure adaptive protection is achieved—preventing high-pressure gas flow from flowing back into the furnace during positive pressure backflow and preventing downstream pollutants from flowing back into the tank during negative pressure conditions. Furthermore, when two sets of exhaust gas treatment devices are symmetrically arranged at both ends of the vertical furnace, they are connected to the top and bottom exhaust ports of the furnace body, respectively. The two sets operate in parallel to achieve bidirectional coordinated collection of exhaust gas throughout the furnace, effectively balancing the pressure field distribution within the furnace and preventing localized airflow turbulence that could lead to eddies. This also provides redundancy – when one set is under maintenance, the other can maintain basic processing functions, ensuring production continuity. The entire process is automated through a PLC control system. A touchscreen displays real-time operating parameters such as pressure, temperature, and liquid level, and provides alarm prompts. Operators can flexibly adjust preset pressure values ​​and liquid level thresholds via the touchscreen according to different process types, enabling the device to adapt flexibly to various process conditions such as oxidation, diffusion, and CVD, meeting the stringent requirements of vertical furnaces for the cleanliness, safety, and stability of the exhaust gas treatment device.

[0037] The above description is merely a preferred embodiment of this utility model and is not intended to 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 backflow prevention tail gas treatment device for a vertical furnace, characterized in that, include: The tank body (700) has an air inlet (704) at the top and an air outlet (720) and a liquid outlet (716) at the bottom. An air intake pipe (702) is connected to the air intake port (704), and the air intake pipe (702) is inclined downward; A one-way valve (706) is provided on the air intake pipe (702); B. One-way valve (718) is located at the air outlet (720); Wherein, the A check valve (706) closes when the pressure inside the tank (700) exceeds a first preset value, and the B check valve (718) closes when the pressure inside the tank (700) is lower than a second preset value.

2. The backflow prevention tail gas treatment device for a vertical furnace according to claim 1, characterized in that, It also includes a filter assembly (710) disposed inside the tank (700), the filter assembly (710) including a detachable metal filter screen and a filter screen holder, the filter screen holder being connected to the inner wall of the tank (700) by a snap fastener.

3. The backflow prevention tail gas treatment device for a vertical furnace according to claim 1, characterized in that, It also includes a buffer assembly (708) disposed inside the tank (700), the buffer assembly (708) including a plurality of guide plates arranged in a spiral shape in the middle of the tank (700).

4. The anti-backflow tail gas treatment device for a vertical furnace according to claim 1, characterized in that, It also includes a condensation recovery assembly, which comprises: A condensate pipe (712) is wrapped around the outside of the tank body (700) to form a condensate jacket; A condensate collection tank is located at the bottom of the tank body (700); The recovery tank is connected to the condensate collection tank via a pipe, and the pipe is equipped with a solenoid valve.

5. The anti-backflow tail gas treatment device for a vertical furnace according to claim 1, characterized in that, The bottom of the tank (700) is conical, the drain port (716) is located at the lowest point of the bottom of the cone, and a shut-off valve (714) is provided at the drain port (716).

6. The anti-backflow tail gas treatment device for a vertical furnace according to claim 1, characterized in that, It also includes a pressure relief valve disposed on the tank (700), which opens when the pressure inside the tank (700) exceeds a third preset value.

7. The anti-backflow tail gas treatment device for a vertical furnace according to claim 1, characterized in that, The inner wall of the tank (700) is provided with a corrosion-resistant coating, which is a ceramic-based composite coating.

8. The backflow prevention tail gas treatment device for a vertical furnace according to claim 1, characterized in that, The tank (700) is provided with an inspection port on the top.

9. A vertical furnace, characterized in that, include: The outer tube (30) is closed at the top and open at the bottom; An inner tube (40) is disposed inside the outer tube (30), and both the upper and lower ends of the inner tube (40) are open; A crystal boat (50) is disposed inside the inner tube (40) and is used to carry the wafer (60). A base (10) is used to support the crystal boat (50) and to close the open end of the outer tube (30); A drive assembly (20) is disposed below the base (10) and is used to drive the base (10) and the crystal boat (50) to rise, fall and rotate.

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