Nitrogen purging system for LPCVD (Low Pressure Chemical Vapor Deposition) silane pipeline
By configuring a purge pipeline in the LPCVD silane pipeline and using nitrogen to regularly purge it, the dust accumulation problem caused by impurities residue in the silane pipeline is solved, and the pipeline stability and product quality are improved.
Patent Information
- Application Number
- CN202422208794.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2025-06-20
- Estimated Expiration
- 2034-09-09
AI Technical Summary
In the LPCVD reaction system, impurities remain on the silane pipeline, resulting in dust accumulation and affecting the quality and production efficiency of the film layer.
A nitrogen purge system for LPCVD silane pipelines is designed, and the silane pipelines are regularly purged by configuring the purging pipelines to remove impurities.
Effectively remove impurities in silane pipelines, avoid dust accumulation, improve pipeline operation stability, and improve product quality and production efficiency.
Smart Images
Figure CN223003020U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of low-pressure chemical vapor deposition (LPCVD), and specifically relates to an LPCVD silane pipeline nitrogen purging system. Background Art
[0002] Chemical vapor deposition (CVD) is a process of depositing a film layer on the surface of a silicon wafer through a chemical reaction after gas mixing. According to the different pressures in the furnace tube in the reaction system, the CVD reaction system can be divided into an atmospheric pressure CVD (APCVD) reaction system and a low-pressure CVD (LPCVD) reaction system. Compared with APCVD, the LPCVD reaction system has lower costs, higher yields, and better film properties, and thus has been more widely used.
[0003] Actual production has found that during the production process of depositing a film layer in the LPCVD reaction system, there will be varying degrees of impurity residues in both the furnace tube reaction chamber and the silane pipeline, resulting in dust accumulation in the silane pipeline and the formation of deposits. The deposits are prone to peeling off during subsequent reactions, and the peeled deposits move with the reaction gas and stay on the wafer, forming dust flakes. The unpeeled deposits will also affect the gas flow in the silane pipeline, easily causing gas flow marks on the film layer deposited on the wafer. Furthermore, this leads to product defects and a reduction in the yield. Therefore, how to effectively remove the impurity residues in the silane pipeline and avoid dust accumulation has become an urgent technical problem in this field. Summary of the Utility Model
[0004] To overcome the problems existing in the related art, the utility model provides an LPCVD silane pipeline nitrogen purging system. A purging pipeline is configured on the silane pipeline, which can regularly purge the silane pipeline to blow out the impurities in the silane pipeline, avoid dust accumulation, improve the stability of the silane pipeline operation, and improve product quality and production efficiency.
[0005] The technical solution adopted by the utility model is as follows: an LPCVD silane pipeline nitrogen purging system, including a reaction gas supply unit, a purging pipeline, a silane pipeline, and a furnace tube;
[0006] The reaction gas supply unit includes an oxygen source, a silane gas source, and a nitrogen source;
[0007] The silane pipeline includes an inlet end and an outlet end. The inlet end of the silane pipeline is connected to the reaction gas supply unit, the outlet end of the silane pipeline is connected to the furnace tube, one end of the purging pipeline is connected to the nitrogen source, and the other end is connected to the outlet end of the silane pipeline.
[0008] Further, the furnace tube includes a first air inlet, a second air inlet, a third air inlet, and a fourth air inlet. The silane pipeline includes an oxygen pipeline, a first silane pipeline, a second silane pipeline, a third silane pipeline, and a nitrogen pipeline. The oxygen pipeline includes a first oxygen inlet end and a first oxygen outlet end. The first silane pipeline includes a first inlet end and a first outlet end. The second silane pipeline includes a second inlet end and a second outlet end. The third silane pipeline includes a third inlet end and a third outlet end. The nitrogen pipeline includes a first nitrogen inlet end and a first nitrogen outlet end;
[0009] The first oxygen inlet end is communicated with an oxygen source. The first oxygen outlet end is communicated with the first air inlet. The first inlet end, the second inlet end, and the third inlet end are communicated with a silane gas source. The first outlet end is communicated with the second air inlet. The second outlet end is communicated with the third air inlet. The third outlet end is communicated with the fourth air inlet. The first nitrogen inlet end is communicated with a nitrogen source. The first nitrogen outlet end is communicated with the first oxygen outlet end.
[0010] Further, the purge pipeline includes a first nitrogen purge pipeline, a second nitrogen purge pipeline, and a third nitrogen purge pipeline. The first nitrogen purge pipeline includes a first nitrogen purge inlet end and a first nitrogen purge outlet end. The second nitrogen purge pipeline includes a second nitrogen purge inlet end and a second nitrogen purge outlet end. The third nitrogen purge pipeline includes a third nitrogen purge inlet end and a third nitrogen purge outlet end;
[0011] The first nitrogen purge inlet end, the second nitrogen purge inlet end, and the third nitrogen purge inlet end are communicated with the nitrogen source. The first nitrogen purge outlet end is communicated with the first outlet end. The second nitrogen purge outlet end is communicated with the second outlet end. The third nitrogen purge outlet end is communicated with the third outlet end.
[0012] Further, the oxygen pipeline is sequentially provided with a first oxygen inlet end, a first pneumatic valve, an oxygen flowmeter, a fourth pneumatic valve, and a first oxygen outlet end.
[0013] Further, the nitrogen pipeline is sequentially provided with a first nitrogen inlet end, a third pneumatic valve, a nitrogen flowmeter, an eighth pneumatic valve, and a first nitrogen outlet end.
[0014] Further, the silane pipeline further includes a second pneumatic valve. One end of the second pneumatic valve is communicated with a silane gas source, and the other end is communicated with a first air inlet end, a second air inlet end and a third air inlet end. The first silane pipeline is sequentially provided with a first air inlet end, a first silane flowmeter, a fifth pneumatic valve, a ninth pneumatic valve and a first air outlet end. The second silane pipeline is sequentially provided with a second air inlet end, a second silane flowmeter, a sixth pneumatic valve, a tenth pneumatic valve and a second air outlet end. The third silane pipeline is sequentially provided with a third air inlet end, a third silane flowmeter, a seventh pneumatic valve, an eleventh pneumatic valve and a third air outlet end.
[0015] Further, the purge pipeline further includes a check valve and a nitrogen tank. The inlet end of the check valve is communicated with the outlet end of the third pneumatic valve, and the outlet end of the check valve is communicated with the inlet of the nitrogen tank. The first nitrogen purge air inlet end, the second nitrogen purge air inlet end and the third nitrogen purge air inlet end are communicated with the outlet of the nitrogen tank. The first nitrogen purge pipeline is sequentially provided with a first nitrogen purge air inlet end, a first flow control valve, a first pressure sensor and a first nitrogen purge air outlet end. The first nitrogen purge air outlet end is arranged on the pipeline between the fifth pneumatic valve and the ninth pneumatic valve. The second nitrogen purge pipeline is sequentially provided with a second nitrogen purge air inlet end, a second flow control valve, a second pressure sensor and a second nitrogen purge air outlet end. The second nitrogen purge air outlet end is arranged on the pipeline between the sixth pneumatic valve and the tenth pneumatic valve. The third nitrogen purge pipeline is sequentially provided with a third nitrogen purge air inlet end, a third flow control valve, a third pressure sensor and a third nitrogen purge air outlet end. The third nitrogen purge air outlet end is arranged on the pipeline between the seventh pneumatic valve and the eleventh pneumatic valve.
[0016] Further, the furnace tube further includes a first air outlet, and the first air outlet is communicated with a suction pipeline. The suction pipeline is sequentially provided with a thirteenth pneumatic valve, a butterfly valve and a suction mercury. The inlet of the thirteenth pneumatic valve is communicated with the first air outlet, and the suction pipeline further includes a suction bypass. The suction bypass includes a twelfth pneumatic valve. The inlet of the twelfth pneumatic valve is communicated with the first air outlet, and the outlet of the twelfth pneumatic valve is communicated with the suction mercury.
[0017] Further, it further includes a purge control unit. The purge control unit includes a timer, a PLC controller, a communication module and a host computer monitoring system. The timer, the first pressure sensor, the second pressure sensor, the third pressure sensor, the first flow control valve, the second flow control valve and the third flow control valve are electrically connected to the PLC controller.
[0018] Further, the second air inlet, the third air inlet and the fourth air inlet are respectively located at three different positions of the front, middle and rear of the furnace tube.
[0019] The nitrogen purging system for the LPCVD silane pipeline of the present utility model has the following technical effects: A purging pipeline is configured on the silane pipeline. The reaction gas supply unit includes an oxygen source, a silane gas source, and a nitrogen source. The inlet end of the purging pipeline is connected to the nitrogen source, and the outlet end of the purging pipeline is connected to the outlet end of the silane pipeline. The nitrogen provided by the nitrogen source is used to periodically purge the silane pipeline. In this way, the residual impurities in the silane pipeline can be effectively removed, dust accumulation can be avoided, the operation stability of the silane pipeline can be improved as a whole, and the product quality and production efficiency can be enhanced.
[0020] Other features and advantages of the present utility model will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The drawings are used to provide a further understanding of the present disclosure and form a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:
[0022] Figure 1 is a schematic diagram of the pipeline connection of an LPCVD silane pipeline nitrogen purging system shown according to an exemplary embodiment.
[0023] Figure 2 is a schematic diagram of the circuit connection of the purging control unit of an LPCVD silane pipeline nitrogen purging system shown according to an exemplary embodiment.
[0024] Reference numerals: 10, oxygen flowmeter; 11, first silane flowmeter; 12, second silane flowmeter; 13, third silane flowmeter; 14, nitrogen flowmeter; 20, first pneumatic valve; 21, second pneumatic valve; 22, third pneumatic valve; 23, fourth pneumatic valve; 24, fifth pneumatic valve; 25, sixth pneumatic valve; 26, seventh pneumatic valve; 27, eighth pneumatic valve; 28, ninth pneumatic valve; 29, tenth pneumatic valve; 30, eleventh pneumatic valve; 31, twelfth pneumatic valve; 32, thirteenth pneumatic valve; 40, first pressure sensor; 41, second pressure sensor; 42, third pressure sensor; 50, check valve; 60, nitrogen tank; 70, first flow control valve; 71, second flow control valve; 72, third flow control valve; 80, butterfly valve; 90, air extraction pump; 100, furnace tube; 110, purging control unit; 111, PLC controller; 112, communication module; 113, upper computer monitoring system; 114, timer. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] The following will describe in detail the specific implementation of the present utility model disclosed in conjunction with the drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and does not limit the present disclosure.
[0026] As Figures 1 to 2 shown, it is an exemplary embodiment disclosed by the present utility model. The LPCVD silane pipeline nitrogen purging system of the present utility model comprises a reaction gas supply unit, a purging pipeline, a silane pipeline and a furnace tube 100; the reaction gas supply unit comprises an oxygen source, a silane gas source and a nitrogen source; the silane pipeline comprises an inlet end and an outlet end, the inlet end of the silane pipeline is communicated with the reaction gas supply unit, the outlet end of the silane pipeline is communicated with the furnace tube 100, one end of the purging pipeline is communicated with the nitrogen source, and the other end is communicated with the outlet end of the silane pipeline.
[0027] The LPCVD silane pipeline nitrogen purging system of the present utility model is configured with a purging pipeline on the silane pipeline. The reaction gas supply unit comprises an oxygen source, a silane gas source and a nitrogen source. One end of the purging pipeline is communicated with the nitrogen source, and the other end is communicated with the silane pipeline. The nitrogen provided by the nitrogen source is used to regularly purge the silane pipeline, and the residual impurities in the silane pipeline are purged out to avoid dust accumulation. In this way, the operation stability of the silane pipeline is improved, and the product quality and production efficiency are improved.
[0028] Exemplarily, as Figure 1 shown, in the exemplary embodiment disclosed by the present utility model, the furnace tube 100 comprises a first air inlet, a second air inlet, a third air inlet and a fourth air inlet. The silane pipeline comprises an oxygen pipeline, a first silane pipeline, a second silane pipeline, a third silane pipeline and a nitrogen pipeline. The oxygen pipeline comprises a first oxygen inlet end and a first oxygen outlet end. The first silane pipeline comprises a first inlet end and a first outlet end. The second silane pipeline comprises a second inlet end and a second outlet end. The third silane pipeline comprises a third inlet end and a third outlet end. The nitrogen pipeline comprises a first nitrogen inlet end and a first nitrogen outlet end;
[0029] The first oxygen inlet end is communicated with the oxygen source, the first oxygen outlet end is communicated with the first air inlet, the first inlet end, the second inlet end and the third inlet end are communicated with the silane gas source, the first outlet end is communicated with the second air inlet, the second outlet end is communicated with the third air inlet, the third outlet end is communicated with the fourth air inlet, the first nitrogen inlet end is communicated with the nitrogen source, and the first nitrogen outlet end is communicated with the first oxygen outlet end.
[0030] The second air inlet, the third air inlet and the fourth air inlet are respectively located at three different positions of the front, middle and rear of the furnace tube 100.
[0031] The furnace tube 100 of the nitrogen purging system for the LPCVD silane pipeline of the present utility model includes a first air inlet, a second air inlet, a third air inlet, and a fourth air inlet. The silane pipeline includes an oxygen pipeline, a first silane pipeline, a second silane pipeline, a third silane pipeline, and a nitrogen-silane pipeline. The first oxygen outlet end of the oxygen pipeline is communicated with the first air inlet, and the first oxygen inlet end is communicated with an oxygen source to provide oxygen for the furnace tube 100 for the silicon oxide process of the LPCVD reaction system. The first nitrogen inlet end of the nitrogen pipeline is communicated with a nitrogen source, and the first nitrogen outlet end is communicated with the first oxygen outlet end. When the LPCVD reaction system completes the silicon oxide process, nitrogen can be injected into the oxygen pipeline to discharge the residual oxygen in the oxygen pipeline and the furnace tube 100. Silane gas is a flammable, explosive, and toxic gas, and the mixing of oxygen and silane gas should be avoided to prevent deflagration. At the same time, the nitrogen pipeline can also introduce nitrogen into the furnace tube 100 through the pipeline between the first oxygen outlet end and the first air inlet for the silicon nitride process of the LPCVD system. The second air inlet, the third air inlet, and the fourth air inlet are respectively located at three different positions in the front, middle, and rear of the furnace tube 100. Correspondingly, the first silane pipeline is communicated with the second air inlet, the second silane pipeline is communicated with the third air inlet, and the third silane pipeline is communicated with the fourth air inlet. Silane gas is introduced into the furnace tube 100 at three different positions in the front, middle, and rear, so that the wafers in the furnace tube 100 can deposit a more uniform film layer.
[0032] Exemplarily, the purging pipeline includes a first nitrogen purging pipeline, a second nitrogen purging pipeline, and a third nitrogen purging pipeline. The first nitrogen purging pipeline includes a first nitrogen purging inlet end and a first nitrogen purging outlet end. The second nitrogen purging pipeline includes a second nitrogen purging inlet end and a second nitrogen purging outlet end. The third nitrogen purging pipeline includes a third nitrogen purging inlet end and a third nitrogen purging outlet end;
[0033] The first nitrogen purging inlet end, the second nitrogen purging inlet end, and the third nitrogen purging inlet end are communicated with a nitrogen source. The first nitrogen purging outlet end is communicated with the first outlet end. The second nitrogen purging outlet end is communicated with the second outlet end. The third nitrogen purging outlet end is communicated with the third outlet end.
[0034] Corresponding to the first silane pipeline, the second silane pipeline, and the third silane pipeline, the purging pipeline includes a first nitrogen purging pipeline, a second nitrogen purging pipeline, and a third nitrogen purging pipeline. The first nitrogen purging inlet end, the second nitrogen purging inlet end, and the third nitrogen purging inlet end are communicated with a nitrogen source. The first nitrogen purging outlet end is communicated with the first outlet end. The second nitrogen purging outlet end is communicated with the second outlet end. The third nitrogen purging outlet end is communicated with the third outlet end to purge the residual silane gas in the first silane pipeline, the second silane pipeline, and the third silane pipeline to prevent it from accumulating into dust and forming deposits.
[0035] Exemplarily, such asFigure 1 As shown, in the exemplary embodiment disclosed by the present utility model, the oxygen pipeline is successively provided with a first oxygen inlet end, a first pneumatic valve 20, an oxygen flowmeter 10, a fourth pneumatic valve 23 and a first oxygen outlet end. The nitrogen pipeline is successively provided with a first nitrogen inlet end, a third pneumatic valve 22, a nitrogen flowmeter 14, an eighth pneumatic valve 27 and a first nitrogen outlet end.
[0036] The silane pipeline further includes a second pneumatic valve 21. One end of the second pneumatic valve 21 is communicated with a silane gas source, and the other end is communicated with a first inlet end, a second inlet end and a third inlet end. The first silane pipeline is successively provided with a first inlet end, a first silane flowmeter 11, a fifth pneumatic valve 24, a ninth pneumatic valve 28 and a first outlet end. The second silane pipeline is successively provided with a second inlet end, a second silane flowmeter 12, a sixth pneumatic valve 25, a tenth pneumatic valve 29 and a second outlet end. The third silane pipeline is successively provided with a third inlet end, a third silane flowmeter 13, a seventh pneumatic valve 26, an eleventh pneumatic valve 30 and a third outlet end.
[0037] The purge pipeline further includes a check valve 50 and a nitrogen tank 60. The inlet end of the check valve 50 is communicated with the outlet end of the third pneumatic valve 22, and the outlet end of the check valve 50 is communicated with the inlet of the nitrogen tank 60. The first nitrogen purge inlet end, the second nitrogen purge inlet end and the third nitrogen purge inlet end are communicated with the outlet of the nitrogen tank 60. The first nitrogen purge pipeline is successively provided with a first nitrogen purge inlet end, a first flow control valve 70, a first pressure sensor 40 and a first nitrogen purge outlet end. The first nitrogen purge outlet end is arranged on the pipeline between the fifth pneumatic valve 24 and the ninth pneumatic valve 28. The second nitrogen purge pipeline is successively provided with a second nitrogen purge inlet end, a second flow control valve 71, a second pressure sensor 41 and a second nitrogen purge outlet end. The second nitrogen purge outlet end is arranged on the pipeline between the sixth pneumatic valve 25 and the tenth pneumatic valve 29. The third nitrogen purge pipeline is successively provided with a third nitrogen purge inlet end, a third flow control valve 72, a third pressure sensor 42 and a third nitrogen purge outlet end. The third nitrogen purge outlet end is arranged on the pipeline between the seventh pneumatic valve 26 and the eleventh pneumatic valve 30.
[0038] The nitrogen purging system for the LPCVD silane pipeline of the present utility model is provided with five flow meters, namely an oxygen flow meter 10, a nitrogen flow meter 14, a first silane flow meter 11, a second silane flow meter 12 and a third silane flow meter 13. To ensure the sensitivity and accuracy of the flow meters, the mixing between the flow meters should be avoided as much as possible. The first pneumatic valve 20 is the total valve for oxygen supply, the second pneumatic valve 21 is the total valve for silane gas supply, and the third pneumatic valve 22 is the total valve for nitrogen supply. The intake end and the outlet end described in this application do not specifically refer to a certain point in the pipeline, but indicate the flow direction of the gas inside the pipeline and the part of the pipeline in the relevant flow direction. For example, the first oxygen intake end in the oxygen pipeline refers to the part of the oxygen pipeline at the end where oxygen enters, and the first oxygen outlet end in the oxygen pipeline refers to the part of the oxygen pipeline at the end where oxygen flows out, and so on.
[0039] The oxygen pipeline is successively provided with a first oxygen intake end, a first pneumatic valve 20, an oxygen flow meter 10, a fourth pneumatic valve 23 and a first oxygen outlet end. There is a relatively long pipeline between the outlet of the oxygen flow meter 10 and the first intake port, so the fourth pneumatic valve 23 is set as an anti-fooling design. The first silane pipeline is successively provided with a first intake end, a first silane flow meter 11, a fifth pneumatic valve 24, a ninth pneumatic valve 28 and a first outlet end. The first nitrogen purging outlet end is arranged on the pipeline between the fifth pneumatic valve 24 and the ninth pneumatic valve 28. The fifth pneumatic valve 24 plays a role in isolating nitrogen to prevent the first nitrogen purging pipeline from introducing nitrogen into the first silane pipeline and contaminating the silane flow meter. The first outlet end is connected to the second intake port through a pipeline, and this pipeline is relatively long. The ninth pneumatic valve 28 plays an anti-fooling role. Similarly, the sixth pneumatic valve 25 and the seventh pneumatic valve 26 both play a role in isolating nitrogen, and the eighth pneumatic valve 27, the tenth pneumatic valve 29 and the eleventh pneumatic valve 30 all play an anti-fooling role. The purging pipeline is provided with a flow control valve and a pressure sensor, which can more precisely control the nitrogen volume and pressure for purging the first silane pipeline, the second silane pipeline and the third silane pipeline. A nitrogen tank 60 is arranged on the purging pipeline, which can store nitrogen to ensure the stability of the nitrogen output pressure.
[0040] Exemplarily, as Figure 2 shown, the nitrogen purging system for the LPCVD silane pipeline of the present utility model further includes a purging control unit 110. The purging control unit 110 includes a timer 114, a PLC controller 111, a communication module 112 and a host computer monitoring system 113. The timer 114, the first pressure sensor 40, the second pressure sensor 41, the third pressure sensor 42, the first flow control valve 70, the second flow control valve 71 and the third flow control valve 72 are electrically connected to the PLC controller 111.
[0041] By setting the purging time and purging duration on timer 114, the timer 114 will send a signal to the PLC controller 111 after reaching the predetermined time. The PLC controller 111 injects nitrogen into the first silane pipeline, the second silane pipeline, and the third silane pipeline through the first flow control valve 70, the second flow control valve 71, and the third flow control valve 72. The first pressure sensor 40, the second pressure sensor 41, and the third pressure sensor 42 feedback the nitrogen pressure of the first nitrogen purging pipeline, the second nitrogen purging pipeline, and the third nitrogen purging pipeline to the PLC controller 111, so as to better assist the PLC controller 111 in adjusting the purging nitrogen pressure.
[0042] Exemplarily, as Figure 1 shown, the furnace tube 100 of the nitrogen purging system for the LPCVD silane pipeline of the present utility model further includes a first air outlet, and the first air outlet is connected to the exhaust pipeline. The exhaust pipeline is sequentially provided with a thirteenth pneumatic valve 32, a butterfly valve 80, and an exhaust pump. The air inlet of the thirteenth pneumatic valve 32 is connected to the first air outlet, and the exhaust pipeline further includes an exhaust bypass, and the exhaust bypass includes a twelfth pneumatic valve 31. The air inlet of the twelfth pneumatic valve 31 is connected to the first air outlet, and the air outlet of the twelfth pneumatic valve 31 is connected to the exhaust pump.
[0043] The furnace tube 100 is provided with a first air outlet, which is connected to the exhaust pipeline. An exhaust pump 90 is provided on the exhaust pipeline, which can extract all the residual gases in the furnace tube 100 and the pipelines connected to the furnace tube 100. The exhaust pipeline is also provided with an exhaust bypass. The exhaust bypass pipeline is smaller, the valve opening is smaller, and the exhaust is slower. By setting an exhaust bypass on the exhaust pipeline, more exhaust requirements can be met.
[0044] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.
[0045] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.
[0046] Furthermore, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.
Claims
1. A LPCVD silane pipeline nitrogen purge system, characterized in that: include: Reactive gas supply unit, purge line, silane line and furnace tube; The reaction gas supply unit includes an oxygen source, a silane gas source and a nitrogen source; The silane pipeline includes an air inlet end and an air outlet end. The air inlet end of the silane pipeline is connected to the reaction gas supply unit, and the air outlet end of the silane pipeline is connected to the furnace pipe. One end of the purge pipeline is connected to the nitrogen source, and the other end is connected to the air outlet end of the silane pipeline.
2. The LPCVD silane pipeline nitrogen purge system according to claim 1, characterized in that: The furnace tube comprises a first air inlet, a second air inlet, a third air inlet and a fourth air inlet, the silane pipeline comprises an oxygen pipeline, a first silane pipeline, a second silane pipeline, a third silane pipeline and a nitrogen pipeline, the oxygen pipeline comprises a first oxygen inlet end and a first oxygen outlet end, the first silane pipeline comprises a first inlet end and a first outlet end, the second silane pipeline comprises a second inlet end and a second outlet end, the third silane pipeline comprises a third inlet end and a third outlet end, and the nitrogen pipeline comprises a first nitrogen inlet end and a first nitrogen outlet end; The first oxygen inlet end is connected to an oxygen source, the first oxygen outlet end is connected to the first air inlet, the first inlet end, the second inlet end and the third inlet end are connected to the silane gas source, the first outlet end is connected to the second inlet, the second outlet end is connected to the third inlet, the third outlet end is connected to the fourth inlet, the first nitrogen inlet end is connected to a nitrogen source, and the first nitrogen outlet end is connected to the first oxygen outlet end.
3. The LPCVD silane pipeline nitrogen purge system according to claim 2, characterized in that: The purge pipeline includes a first nitrogen purge pipeline, a second nitrogen purge pipeline and a third nitrogen purge pipeline, the first nitrogen purge pipeline includes a first nitrogen purge inlet end and a first nitrogen purge outlet end, the second nitrogen purge pipeline includes a second nitrogen purge inlet end and a second nitrogen purge outlet end, and the third nitrogen purge pipeline includes a third nitrogen purge inlet end and a third nitrogen purge outlet end; The first nitrogen purge inlet end, the second nitrogen purge inlet end and the third nitrogen purge inlet end are connected to the nitrogen source, the first nitrogen purge outlet end is connected to the first outlet end, the second nitrogen purge outlet end is connected to the second outlet end, and the third nitrogen purge outlet end is connected to the third outlet end.
4. The LPCVD silane pipeline nitrogen purge system according to claim 2, characterized in that: The oxygen pipeline is sequentially provided with a first oxygen inlet end, a first pneumatic valve, an oxygen flow meter, a fourth pneumatic valve and a first oxygen outlet end.
5. The LPCVD silane pipeline nitrogen purge system according to claim 3, characterized in that: The nitrogen pipeline is sequentially provided with a first nitrogen inlet end, a third pneumatic valve, a nitrogen flow meter, an eighth pneumatic valve and a first nitrogen outlet end.
6. The LPCVD silane pipeline nitrogen purge system according to claim 5, characterized in that: The silane pipeline also includes a second pneumatic valve, one end of which is connected to the silane gas source, and the other end is connected to the first air inlet end, the second air inlet end and the third air inlet end. The first silane pipeline is sequentially provided with a first air inlet end, a first silane flowmeter, a fifth pneumatic valve, a ninth pneumatic valve and a first air outlet end. The second silane pipeline is sequentially provided with a second air inlet end, a second silane flowmeter, a sixth pneumatic valve, a tenth pneumatic valve and a second air outlet end. The third silane pipeline is sequentially provided with a third air inlet end, a third silane flowmeter, a seventh pneumatic valve, an eleventh pneumatic valve and a third air outlet end.
7. The LPCVD silane pipeline nitrogen purge system according to claim 6, characterized in that: The purge pipeline also includes a check valve and a nitrogen tank. The air inlet end of the check valve is communicated with the air outlet end of the third pneumatic valve, and the air outlet end of the check valve is communicated with the air inlet of the nitrogen tank. The first nitrogen purge air inlet end, the second nitrogen purge air inlet end and the third nitrogen purge air inlet end are communicated with the air outlet of the nitrogen tank. The first nitrogen purge pipeline is provided with a first nitrogen purge air inlet end, a first flow control valve, a first pressure sensor and a first nitrogen purge air outlet end in sequence. The first nitrogen purge air outlet end is provided between the fifth pneumatic valve and the third pneumatic valve. On the pipeline between the nine pneumatic valves, the second nitrogen purge pipeline is sequentially provided with a second nitrogen purge inlet end, a second flow control valve, a second pressure sensor and a second nitrogen purge outlet end, and the second nitrogen purge outlet end is arranged on the pipeline between the sixth pneumatic valve and the tenth pneumatic valve, and the third nitrogen purge pipeline is sequentially provided with a third nitrogen purge inlet end, a third flow control valve, a third pressure sensor and a third nitrogen purge outlet end, and the third nitrogen purge outlet end is arranged on the pipeline between the seventh pneumatic valve and the eleventh pneumatic valve.
8. The LPCVD silane pipeline nitrogen purge system according to claim 1, characterized in that: The furnace tube also includes a first air outlet, which is connected to an exhaust pipeline. The exhaust pipeline is provided with a thirteenth pneumatic valve, a butterfly valve and an exhaust valve in sequence. The air inlet of the thirteenth pneumatic valve is connected to the first air outlet, and the exhaust pipeline also includes an exhaust bypass. The exhaust bypass includes a twelfth pneumatic valve, the air inlet of the twelfth pneumatic valve is connected to the first air outlet, and the air outlet of the twelfth pneumatic valve is connected to the exhaust valve.
9. The LPCVD silane pipeline nitrogen purge system according to claim 7, characterized in that: It also includes a purge control unit, which includes a timer, a PLC controller, a communication module, and a host computer monitoring system. The timer, the first pressure sensor, the second pressure sensor, the third pressure sensor, the first flow control valve, the second flow control valve, and the third flow control valve are electrically connected to the PLC controller.
10. The LPCVD silane pipeline nitrogen purge system according to claim 2, characterized in that: The second air inlet, the third air inlet and the fourth air inlet are respectively located at three different positions of the front, the middle and the rear of the furnace tube.