A pneumatic piston valve suitable for an atomic layer deposition coating apparatus

Abstract

The application discloses a kind of pneumatic plunger valves suitable for atomic layer deposition coating device, including hopper, inclined material pipe, lateral tee pipe and plunger valve assembly.The inner wall of the inlet end of inclined material pipe is structured from top to bottom by first necking section, second transition section and third flow passage section with increasing inner diameter;Lateral tee pipe includes straight pipe and lateral branch pipe;Plunger valve assembly includes plunger rod and sealing head, sealing head sequentially includes first cylinder, second cone and third cylinder along the axial direction, respectively with first necking section guiding positioning cooperation, with second transition section taper sealing, with straight pipe sliding sealing.The plunger valve adopts lateral wall installation mode, through the multi-stage variable-diameter structure of sealing head and the step-by-step cooperation of stepped inclined lateral wall, reliable sealing and fast opening and closing under high vacuum are realized, nitrogen pressure difference push and suction and stirring are cooperated, powder efficient and stable transfer is completed, suitable for powder ALD process under high negative pressure environment.

Description

Technical Field

[0001] This invention belongs to the field of atomic layer deposition (ALD) powder processing equipment and valve control technology, specifically relating to a pneumatic plunger valve suitable for atomic layer deposition coating devices, especially suitable for micro-pressure difference synergistic stable transfer of 50kg-level powder under high negative pressure environment. Background Technology

[0002] In the large-scale production of atomic-layer coated powders, powder transfer between multiple reactors is a critical step affecting coating uniformity and process stability. For example... Figure 1 The diagram shows a partial schematic of a prior art continuous atomic layer deposition (ALD) powder coating apparatus. This apparatus includes multiple ALD growth cycle units connected in series via pipes. Each ALD growth cycle unit includes a first reactor and a second reactor connected in series. Both the first and second reactors include a reaction chamber and a purification chamber, with the purification chamber located below the reaction chamber. A stirring device is installed above the reaction chamber, with its blades extending to the bottom of the reaction chamber. The side of the reaction chamber of the first reactor is also connected to the inlet of a feed inlet pipe. The inlet of the feed inlet pipe of the first reactor's reaction chamber is connected to a feed tank (not shown). The bottom of the purification chamber is connected to the inlet of a feed outlet pipe. The outlet of the feed outlet pipe of the first reactor is connected to the feed inlet pipe of the second reactor. The outlet of the feed outlet pipe of the second reactor is connected to a discharge tank. Each reaction chamber is also connected to a tail gas exhaust pipe. Vacuum valves are installed on the feed inlet and outlet pipes between each reactor. These existing valves (such as ball valves, butterfly valves, and gate valves) have the following drawbacks when applied to high-vacuum powder ALD equipment: Poor vacuum sealing: Conventional valves are difficult to achieve zero leakage under vacuum, which can easily lead to vacuum fluctuations and precursor cross-contamination, thus compromising the repeatability of the ALD self-limiting reaction. Powder residue and agglomeration: Dead corners and grooves in the valve flow channel make it easy for material to accumulate and bridge, causing powder agglomeration and cross-contamination between batches, affecting the uniformity of the coating layer; Weak dust resistance: Ultrafine powder can easily penetrate the sealing surface, causing valve jamming, accelerated wear, and shortening equipment life; Poor automation adaptability: slow start-up and shutdown response, insufficient control precision, and difficulty in achieving linkage and closed-loop control with ALD vacuum, stirring, and gas circuit systems, which restricts continuous production; Insufficient stability of negative pressure material transfer: Under negative pressure, the opening of conventional valves is prone to backflow of gas, backflow of powder, or blockage of pipes, making it impossible to achieve stable powder transfer and easily disrupting the negative pressure balance of the system.

[0003] Therefore, developing a valve system that is compatible with high-vacuum powder ALD process, has no material residue, is dust resistant, and can be automatically controlled, while achieving efficient and stable material transfer under high negative pressure environment through simultaneous vacuuming of two reactors and micro-nitrogen pressure differential push suction in the feed pipe, has significant engineering value. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a valve system that can achieve efficient and stable material transfer under high negative pressure environment by simultaneously evacuating the two reactors and pushing and sucking the material through the micro-nitrogen pressure difference in the feed pipe.

[0005] To solve the above-mentioned technical problems, the present invention provides a pneumatic plunger valve suitable for powder ALD equipment. The valve is installed on the side wall of the bottom hopper of the ALD reactor and includes an inclined feed pipe, a lateral three-way pipe and a plunger valve assembly.

[0006] Specifically, the inclined feed pipe is connected to the hopper, and the inner wall of the inlet end of the inclined feed pipe is constructed as a tapering tubular structure with the inner diameter decreasing from bottom to top. A lateral tee pipe includes a straight pipe and a side branch pipe. The inlet of the straight pipe is connected to the outlet of the inclined feed pipe. The side branch pipe is located on the side wall of the straight pipe. The outlet of the side branch pipe is connected to the feed pipe through a flange. The feed pipe is used to feed materials to the next stage ALD reactor. And a plunger valve assembly, including a valve chamber, a plunger rod slidably housed within the valve chamber, and a plug head mounted on the top of the plunger rod, the plug head being located outside the valve chamber and axially sliding within the straight pipe and the inclined feed pipe, the outlet of the straight pipe being connected to the valve chamber via a flange. The sealing head is constructed axially from top to bottom as a mating part adapted to the constricted tubular structure. When the sealing head is pushed by the plunger rod to the inner wall of the inlet end of the inclined material pipe, the sealing head and the constricted tubular structure form a mating.

[0007] The constricted tubular structure consists of a first constricted section, a second transition section, and a third flow channel section with increasing inner diameter from top to bottom; the mating parts include a first column, a second cone, and a third column from top to bottom, the first column is clearance-fitted with the first constricted section, the second cone is transition-fitted with the second transition section, and the third column is clearance-fitted with the straight pipe.

[0008] The sealing head is constructed as a stepped shaft with multiple diameter variations, with the outer diameter of each segment increasing progressively from top to bottom. The outer diameter of the small end of the second cone is equal to the outer diameter of the first column, and the outer diameter of the large end of the second cone is equal to the outer diameter of the third column.

[0009] The second cone and the third column are fitted with at least one sealing ring on their outer periphery; the sealing ring is an O-ring.

[0010] The inclined feed pipe is integrally formed with the hopper, and the outlet of the inclined feed pipe and the inlet of the straight pipe are coaxially connected by a flange and have the same inner diameter.

[0011] The straight pipe sidewall is provided with a nitrogen gas supply port, which is connected to the inert gas path and equipped with a micro regulating valve.

[0012] The plunger rod is constructed as a multi-stage variable diameter rod, which includes a small diameter section, a medium diameter section and a large diameter section in sequence. The diameter of the valve cavity outlet end is equal to the diameter of the medium diameter section, so that the plunger rod can extend from the valve cavity outlet end to the large diameter section and be locked by the limiting shoulder.

[0013] The inner walls of the straight tube and the inclined tube are polished to a roughness Ra≤0.4μm.

[0014] The lower end of the valve chamber is connected to a compressed gas pipeline.

[0015] A storage tank is also connected in series between the feed pipe and the next-stage ALD reactor.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Excellent sealing performance, suitable for high negative pressure environments.

[0017] This invention employs a three-stage variable diameter sealing head structure and a progressively fitting design with the inner wall of the inclined feed tube inlet. A multi-layered sealing system is formed through the guiding and positioning of the first column and the first constriction section, the conical surface sealing of the second cone and the second transition section, and the sliding seal of the third column and the straight tube. The conical surface line seal structure of the second cone and the second transition section achieves a high-vacuum seal when the plunger valve is closed, with a single-reactor vacuum fluctuation ≤10Pa, meeting the stringent requirements of the 0.02 torr high negative pressure environment of the ALD process, effectively avoiding gas crosstalk and precursor contamination.

[0018] 2. The flow channel is unobstructed and free of dead corners, preventing powder adhesion and residue.

[0019] The inclined feed tube and hopper are integrally formed with polished inner walls (Ra≤0.4μm). The three sections of the stepped inclined sidewall have progressively increasing inner diameters, matching the three-stage structure of the sealing head to form a smooth and continuous material channel. The straight pipe of the lateral tee is coaxial with the inclined feed tube and has the same inner diameter. The side branch pipe discharges material laterally, forming a lateral tee flow channel without grooves or dead corners, avoiding powder adhesion and residue, reducing powder flow resistance, and is especially suitable for powder flow in negative pressure environments without airflow assistance.

[0020] 3. Side wall mounting does not occupy internal space of the reactor.

[0021] The plunger valve is installed on the side wall of the ALD reactor via a lateral tee pipe. The first port of the straight pipe connects to the inclined feed pipe flange, the second port connects to the plunger valve assembly, and the side branch pipe connects to the feed pipe. This installation method does not occupy the internal stirring and gas path space of the reactor, is suitable for compact layouts of multiple reactors, and leaves ample space for internal process operations.

[0022] 4. Quick and precise opening and closing, high material transfer efficiency.

[0023] The plunger rod adopts a multi-stage variable diameter rod structure and is driven by a double-acting pneumatic actuator. Combined with a solenoid valve and position feedback sensor, it achieves a rapid response with an opening and closing time of ≤2 seconds. The plunger rod slides within the valve chamber, and its maximum stroke is precisely controlled by the coarse-diameter section and the limiting shoulder at the valve chamber outlet. This ensures precise contact or complete disengagement between the sealing head and the inclined material pipe sealing surface, forming a full-bore flow channel. This allows for precise control of the material transfer timing, enabling the complete transfer of 50kg of powder within 5 minutes.

[0024] 5. Differential pressure suction and mechanical stirring work together to prevent bridging and backflow.

[0025] A nitrogen supply port is installed on the side wall of the side branch pipe outlet, allowing the introduction of a micro-flow of inert nitrogen (0-50 sccm). This creates a gentle positive pressure pushing force at the intersection of the straight pipe and the side branch pipe, which, combined with the high negative pressure adsorption force of the feed vessel, achieves dual-powered pressure differential pushing and suction through nitrogen and vacuum. Simultaneously, the flow channel port is aligned with the stirring area of ​​the reactor, working in conjunction with the mechanical pushing of the stirring system to form a dual synergy of pressure differential pushing and suction and mechanical stirring. This effectively prevents powder bridging and clogging, and eliminates powder backflow and scattering.

[0026] 6. Self-cleaning function, easy maintenance.

[0027] The third column of the plugging head is fitted with a clearance fit against the inner wall of the straight pipe and is equipped with multiple sealing rings. During the reciprocating motion of the plunger, the third column slides along the inner wall of the straight pipe, scraping away residual powder and achieving self-cleaning of the flow channel. The sealing rings are O-rings, installed in the groove on the outer circumference of the plugging head, making replacement convenient and maintenance costs low. Regularly performing the plunger reciprocating cleaning action (10 times / batch) effectively prevents powder deposition and ensures long-term stable operation.

[0028] 7. Simple and reliable structure, low manufacturing cost. The stepped inclined sidewall at the inlet end of the inclined feed tube consists of a cylindrical inner wall (first constriction section, third flow channel section) and a conical inner wall (second transition section), both of which are conventionally machined surfaces, easy to turn and bore, and have low manufacturing difficulty. The three-stage structure of the sealing head (first column, second cone, third column) is a rotating part, which is easy to machine. The overall structure is simple, without complex curved surfaces, significantly reducing machining and maintenance costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a partial apparatus for continuous atomic layer deposition coating of powder in the prior art. Figure 2 This is a diagram of the connection structure of a plunger valve; Figure 3 This is a schematic diagram of the cross-sectional structure of a plunger valve; Among them, 1-hopper, 2-inclined material pipe, 3-side tee pipe, 4-plunger valve assembly, 5-air source inlet; 6-air seal reserved interface. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention. In this embodiment, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0031] like Figure 2 The diagram shows the overall structure of the pneumatic plunger valve in this embodiment. The valve body is installed on the side wall of the ALD reactor and is used for powder transfer control between reactors and between the reactor and the feed hopper. An inclined feed pipe 2, integrally formed with the hopper 1 at the bottom of the ALD reactor (currently the discharge vessel), is connected to the plunger valve assembly 4 and the feed pipe (feed pipe) via a lateral tee pipe 3. Figure 2 (Not shown in the diagram) Specifically, the lateral tee pipe 3 includes a straight pipe 31 and a side branch pipe 32. The straight pipe 31 serves as the extension channel for the plunger rod 41 in the plunger valve assembly 4, and the side branch pipe 32, located on the side wall of the straight pipe 31, connects to the feed pipe. The first port of the straight pipe 31 is connected to the outlet of the inclined feed pipe 2 via a flange, the second port of the straight pipe 31 is connected to the top of the plunger valve assembly 4 via a flange, and the outlet of the side branch pipe 32 is connected to the feed pipe via a flange. The straight pipe of the lateral tee pipe 3 and the inclined feed pipe 2 are coaxially mounted and have the same inner diameter.

[0032] like Figure 3 As shown, the inclined feed pipe 2, connected to the inner wall of the inlet end of the side wall of the hopper 1, is constructed as a constricted tubular structure consisting of a first constriction section, a second transition section, and a third flow channel section, with increasing inner diameter from top to bottom. The first constriction section connects to the bottom connection port of the hopper 1, and the third flow channel section is the main pipe of the inclined feed pipe 2. Figure 3As shown, the plunger valve assembly 4 includes a plunger rod 41 and a valve cavity 42 that accommodates the plunger rod 41. The plunger rod 41 is constructed as a multi-stage variable diameter rod, which consists of a mating part composed of a small diameter section, a medium diameter section and a large diameter section from top to bottom. The diameters of the small diameter section, the medium diameter section and the large diameter section increase sequentially. The diameter of the outlet end of the valve cavity 42 is equal to the diameter of the medium diameter section of the plunger rod 41. In this way, the plunger rod 41 can extend from the outlet port diameter of the valve cavity 42 to its end of the large diameter section, which is then held by the limiting shoulder at the outlet end of the valve cavity 42, so that the plunger rod 41 extends to its maximum stroke.

[0033] A sealing head 43 is installed at the top of the small diameter section of the plunger rod 41. The sealing head 43 is constructed as a stepped shaft with multiple diameter changes. Along the axial direction from the end near the plunger to the end away from the plunger, it includes a first column, a second cone, and a third column in sequence, and the outer diameter of each section increases progressively. The outer diameter of the small end of the second cone is equal to the diameter of the first column, and the outer diameter of the large end of the second cone is equal to the outer diameter of the third column.

[0034] The plug head 43 installed at the top of the small diameter section of the plunger rod 41 can slide axially within the straight pipe 31 and the inclined material pipe 2 of the lateral tee pipe 3.

[0035] The cylindrical surface of the third column of the plugging head 43 is in clearance fit with the inner wall surface of the straight pipe 31 of the lateral tee pipe 3 and the main pipe of the inclined material pipe 2. Multiple sealing rings 44 are embedded on the outer periphery of the third column of the plugging head 43, forming a sliding seal with the straight pipe 31 of the lateral tee pipe 3 and the inner wall surface of the main pipe of the inclined material pipe 2 through the sealing rings 44. The conical surface of the second cone of the plugging head 43 is in transition fit with the conical inner wall surface of the second transition section at the inlet end of the inclined material pipe 2. At least one sealing ring 44 is embedded on the outer periphery of the second cone of the plugging head 43, forming a conical surface seal. The cylindrical surface of the first column of the plugging head 43 is in clearance fit with the cylindrical inner wall surface of the first constriction section at the inlet end of the inclined material pipe 2, forming a guiding and positioning function.

[0036] The straight pipe 31 of the lateral three-way pipe 3 serves as the telescopic channel for the plunger rod 41 in the plunger valve assembly 4. The inner wall of the straight pipe 31 is polished (roughness Ra≤0.4μm) to reduce the flow resistance of powder and prevent agglomeration. The straight pipe 31, together with the inclined material pipe 2 and the conveying pipe, forms a lateral three-way flow channel, which smoothly transitions with the inner wall of the reactor without grooves, avoiding powder adhesion and residue, and providing a guiding basis for the smooth flow of powder under negative pressure.

[0037] A nitrogen supply port is added to the side wall of the outlet of the side branch pipe 32 of the side tee pipe 3. The port is connected to the inert gas path and equipped with a micro regulating valve, which can achieve precise control of nitrogen flow rate from 0 to 50 sccm. This provides a stable airflow driving force for pressure differential push-suction material transfer, ensuring that the powder does not float, does not block the pipe, and leaves no residue.

[0038] A double-acting pneumatic actuator drives the plunger rod 41, which, in conjunction with a solenoid valve and a position feedback sensor, enables rapid valve opening and closing (opening and closing time ≤ 2s) and precise position feedback, ensuring accurate and controllable material transfer timing. The plunger rod 41 can slide axially within the valve chamber 42, with its maximum stroke controlled by the rough-diameter section and the limiting shoulder at the valve chamber outlet. This actuator can be linked with the PLC control system of the ALD equipment, enabling not only automated triggering of material transfer actions but also linkage with the dual vacuum pump group, stirring system, and inert gas path to achieve integrated control of simultaneous vacuuming of the two reactors, vacuum balancing and pressure maintenance, micro-nitrogen purging of the material pipe to build differential pressure, material transfer, and vacuum isolation, meeting the core requirements of differential pressure push-suction material transfer under high negative pressure.

[0039] The sealing ring 44 adopts an O-ring sealing structure, which is embedded in the outer periphery of the third column (multiple rings) and the outer periphery of the second cone (at least one ring) of the sealing head 43. The structure is simple, the processing and maintenance costs are lower, and the installation and replacement of O-rings are very convenient. The third column is fitted with the inner wall of the straight pipe 31 with a clearance and sliding seal, and the second cone is sealed with the conical surface of the second transition section of the inclined material pipe 2. Stable sealing can be achieved under high vacuum, with no leakage and no cross-flow, providing a reliable vacuum foundation for the vacuum balance of the dual reactor and the pressure difference push suction transfer of materials.

[0040] The steps of the control method of the pneumatic plunger valve material transfer system of the present invention in the powder ALD process (high negative pressure environment) are as follows: 1. Simultaneous vacuuming and vacuum balancing pressure maintenance in both reactors.

[0041] Before material transfer, the plunger rod 41 drives the sealing head 43 upward until the first column is fully inserted into the first constriction section of the inclined material pipe 2, and the second cone is tightly fitted with the second transition section of the inclined material pipe 2. The plunger closes, making the two reactors completely vacuum isolated. The PLC control system links the dual vacuum pump group to simultaneously evacuate the discharge reactor and the feed reactor until both reactors are stable at the high negative pressure required by the ALD process. The pressure of the two reactors is monitored in real time by a high-precision pressure sensor to ensure that the pressure fluctuation of a single reactor is ≤10Pa and the pressure difference between the two reactors is ≤5Pa. After the vacuum meets the standard, the vacuum pumps of the two reactors maintain a micro-pumping and pressure-maintaining state to prevent vacuum fluctuations caused by slight leakage in the cavity. This lays a undisturbed and pressure-free vacuum foundation for subsequent pressure differential push-suction material transfer, and avoids gas backflow and powder backflow after valve opening from the root.

[0042] 2. Process linkage triggering and valve opening.

[0043] After the dual-reactor vacuum balance and pressure holding, the PLC system sends a material transfer signal according to the ALD process stage. The double-acting pneumatic actuator drives the plunger rod 41 to descend rapidly (opening and closing time ≤ 2s). The sealing head 43 disengages from the second transition section of the inclined material pipe 2, and the third column slides upward along the inner wall of the straight pipe 31 until the third column approaches or enters the end of the straight pipe 31 of the lateral three-way pipe 3. The plunger valve opens, forming a straight powder conveying channel from the discharge vessel to the inclined material pipe 2, the lateral three-way pipe 3, the straight pipe 31, the side branch pipe 32, the conveying pipe, and the feed vessel. The position feedback sensor provides real-time feedback on the position of the plunger rod 41, ensuring that the second cone of the sealing head 43 completely disengages from the inclined material pipe 2, forming a full-bore flow channel, allowing the powder and the micro-pressure differential airflow to pass through without obstruction.

[0044] 3. The feed pipe is micro-purified with nitrogen, and the negative pressure adsorption pressure difference pushes and transfers the material.

[0045] As the plunger valve opens, the PLC activates the nitrogen supply port on the side wall of the side branch pipe 32 to introduce a small flow of inert nitrogen (flow rate 10~30 sccm) into the flow channel, creating a gentle positive pressure pushing force at the intersection of the straight pipe 31 and the side branch pipe 32. Combined with the adsorption force continuously generated by the high negative pressure of the feed vessel, the pressure difference push and suction of the nitrogen conveying in the feed pipe and the vacuum suction in the feed vessel are driven by the airflow. The powder moves smoothly towards the feed vessel along the smooth flow channel of the inclined feed pipe 2, the straight pipe 31, and the side branch pipe 32 under the influence of the airflow.

[0046] 4. Forced material transfer through a combination of pushing and suction and stirring.

[0047] While the pressure differential pushes and sucks, the stirring systems of the discharge vessel and the feed vessel are simultaneously activated: the paddle agitator disperses the agglomerated powder at high speed, preventing bridging between the discharge vessel inlet and the first closing section of the inclined feed pipe 2; the mechanical force of the agitation forms a directional pushing force, assisting the powder to enter the inclined feed pipe 2, avoiding powder retention at the discharge end, and achieving dual synergistic material transfer through pressure differential push and suction and mechanical stirring; during the material transfer process, the vacuum pump of the feed vessel continuously performs micro-pumping and pressure replenishment to maintain a high process vacuum at all times, and the discharge vessel simultaneously performs micro-pressure replenishment as the powder decreases, ensuring that the two vessels always maintain a small pressure gradient, and the negative pressure of the entire system is stable at 0.02 torr ± 0.001 torr, with no powder flying, no backflow, and no pipe blockage.

[0048] 5. Vacuum isolation and flow channel cleaning.

[0049] After the material transfer is completed, the plunger rod 41 moves upward rapidly, the third column of the sealing head 43 slides along the inner wall of the straight pipe 31, the second cone of the sealing head 43 fits and seals with the second transition section of the inclined material pipe 2, the first column of the sealing head 43 enters the first constriction section for guidance and positioning, the plunger valve closes, the vacuum sealing assembly immediately establishes high vacuum isolation, and cuts off the nitrogen gas supply to the side branch pipe 32; the feed vessel continues to maintain the process negative pressure to prepare for the subsequent ALD reaction, and the discharge vessel can continue to be evacuated or replaced with inert gas according to process requirements to ensure that the negative pressure of the two vessels is independent and to avoid gas crosstalk and precursor contamination; subsequently, the system automatically introduces a short pulse of inert gas (such as nitrogen, flow rate 50 sccm, lasting 1 second) into the side branch pipe 32 to purge residual powder on the inner wall of the flow channel; the plunger rod 41 is periodically reciprocated (10 times / batch), and the sliding cooperation between the third column of the sealing head 43 and the straight pipe 31 is used to scrape off the residue, prevent powder deposition, and prepare for the next pressure differential push-suction material transfer.

[0050] 6. Fault protection and redundancy control.

[0051] If a vacuum leak or plunger rod 41 jams, the system immediately shuts off the corresponding reactor vacuum line and initiates backup nitrogen purging to prevent precursor leakage and equipment damage. Manual bypass control is supported, allowing manual intervention in the material transfer process during automation failures to ensure continuous negative pressure material transfer. Optionally, a very weak pulse of inert gas can be introduced into the discharge vessel during material transfer, making the discharge pressure slightly higher than the inlet pressure by tens of Pascals, creating a slight pressure differential to further improve powder flow smoothness without disrupting the overall high vacuum environment.

[0052] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A pneumatic plunger valve suitable for atomic layer deposition coating apparatus, characterized in that, The side wall of the bottom hopper (1) of the ALD reactor is installed, including: Inclined feed pipe (2) is connected to the hopper (1), and the inner wall of the inlet end of the inclined feed pipe (2) is constructed as a constricted tubular structure with the inner diameter decreasing from bottom to top; The lateral tee pipe (3) includes a straight pipe (31) and a side branch pipe (32). The inlet of the straight pipe (31) is connected to the outlet of the inclined material pipe (2). The side branch pipe (32) is opened on the side wall of the straight pipe (31). The outlet of the side branch pipe (32) is connected to the conveying pipe. The conveying pipe is used to convey materials to the next stage ALD reactor. The plunger valve assembly (4) includes a valve chamber (42), a plunger rod (41) slidably accommodated in the valve chamber (42), and a plug (43) mounted on the top of the plunger rod (41). The plug (43) is located outside the valve chamber (42) and can slide axially within the straight pipe (31) and the inclined feed pipe (2). The outlet of the straight pipe (31) is connected to the valve chamber (42) via a flange. The plug (43) is axially configured from top to bottom as a mating part adapted to the constricted tubular structure. When the plug (43) is pushed by the plunger rod (41) to the inner wall of the inlet end of the inclined feed pipe (2), the plug (43) forms a mating with the constricted tubular structure.

2. The pneumatic plunger valve according to claim 1, characterized in that, The constricted tubular structure consists of a first constricted section, a second transition section, and a third flow channel section with increasing inner diameter from top to bottom; the mating parts include a first column, a second cone, and a third column from top to bottom, the first column is in clearance fit with the first constricted section, the second cone is in transition fit with the second transition section, and the third column is in clearance fit with the straight pipe (31).

3. The pneumatic plunger valve according to claim 1, characterized in that, The sealing head (43) is constructed as a stepped shaft with multiple diameter changes, with the outer diameter of each segment increasing progressively from top to bottom. The outer diameter of the small end of the second cone is equal to the outer diameter of the first column, and the outer diameter of the large end of the second cone is equal to the outer diameter of the third column.

4. The pneumatic plunger valve according to claim 1, characterized in that, The second cone and the third column are fitted with at least one sealing ring (44) on their outer periphery; the sealing ring (44) is an O-ring.

5. The pneumatic plunger valve according to claim 1, characterized in that, The inclined material pipe (2) is integrally formed with the hopper (1), and the outlet of the inclined material pipe (2) is coaxially connected to the inlet of the straight pipe (31) through a flange and has the same inner diameter.

6. The pneumatic plunger valve according to claim 1, characterized in that, The straight pipe (31) has a nitrogen supply port on its side wall. The nitrogen supply port is connected to the inert gas path and is equipped with a micro regulating valve.

7. The pneumatic plunger valve according to claim 1, characterized in that, The plunger rod (41) is constructed as a multi-stage variable diameter rod, which includes a small diameter section, a medium diameter section and a large diameter section in sequence. The diameter of the outlet end of the valve cavity (42) is equal to the diameter of the medium diameter section, so that the plunger rod (41) can extend from the outlet end of the valve cavity (42) to the large diameter section and be locked by the limiting shoulder.

8. The pneumatic plunger valve according to claim 1, characterized in that, The inner walls of the straight tube (31) and the inclined tube (2) are polished to a roughness Ra≤0.4μm.

9. The pneumatic plunger valve according to claim 1, characterized in that, The lower end of the valve chamber (42) is connected to a compressed gas pipeline.

10. The pneumatic plunger valve according to claim 1, characterized in that, A storage tank is also connected in series between the feed pipe and the next-stage ALD reactor.

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