Plasma enhanced chemical vapor deposition equipment

Abstract

The invention discloses plasma enhanced chemical vapor deposition equipment which comprises a reaction cavity, a heating disc arranged in the reaction cavity, a gas uniformizing disc arranged in the reaction cavity and located above the heating disc, and a conductive cover cap covering the gas uniformizing disc so as to form a buffer gas cavity in the conductive cover cap. A transfer cavity covering the furnace door is further arranged outside the reaction cavity, an electric fork hand for feeding or taking a wafer into or out of the reaction cavity is arranged in the transfer cavity, a placing opening is formed in the top of the transfer cavity and located above the initial stop position of the electric fork hand, a sealing cover plate is arranged on the placing opening, and the sealing cover plate is arranged on the top of the transfer cavity. The conveying cavity is further provided with a second vacuum extraction opening and an atmosphere communication opening, the second vacuum extraction opening is connected with the vacuumizing device through a second extraction pipe, and the atmosphere communication opening is communicated with the atmosphere through an atmosphere communication pipe. The device has the advantages that the vacuum environment in the cavity cannot be damaged and pollution in the cavity is avoided when the cavity door of the reaction cavity is opened, and the quality of vapor deposition on the surface of the wafer is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor manufacturing equipment, and particularly relates to a plasma enhanced chemical vapor deposition equipment for depositing a thin film on a wafer. BACKGROUND

[0002] At present, the plasma enhanced chemical vapor deposition process for depositing a film structure on a wafer surface is often used in the semiconductor manufacturing process. The plasma enhanced chemical vapor deposition equipment in the prior art comprises a reaction cavity, a heating disc for placing a wafer, a radio frequency source and the like are arranged in the reaction cavity, process gas is introduced into the reaction cavity through a gas pipe, and a thin film structure is formed on the wafer surface under the action of the radio frequency source.

[0003] In the working process of the plasma enhanced chemical vapor deposition equipment, the reaction cavity should be in a vacuum state. However, placing a wafer in the reaction cavity or taking out the wafer from the reaction cavity inevitably requires opening the cavity door, which inevitably destroys the vacuum state of the cavity and causes the interior of the reaction cavity to be directly connected with the atmosphere, and the following defects exist:

[0004] 1. Each time the cavity door is opened, the vacuum state in the cavity is destroyed, and it is necessary to re-pump and reach a stable state. Frequent operation increases the burden of the vacuum system, which may cause the vacuum pump to overheat or the efficiency to decrease, and further affect the deposition rate and the quality of the thin film;

[0005] 2. The radio frequency power source needs to re-stabilize the glow discharge, and frequent switching may cause the plasma density to fluctuate, and further affect the chemical reaction rate and the uniformity of the thin film;

[0006] 3. Each time the cavity door is opened, the internal structure is exposed to contact with the air, which may increase the risk of particle contamination. If not cleaned in time, the contaminants will be deposited on the wafer surface, causing the adhesion of the thin film to decrease or the performance to be unstable;

[0007] 4. Frequent switching may cause parameters such as temperature and pressure to be unable to be stably controlled, for example, the radio frequency power needs to be recalibrated, which affects the density and adhesion of the thin film.

[0008] In addition, the process gas is mixed by a plurality of gases, and the types of mixed gases are different for different products and different process conditions. In the prior art, a gas conveying pipe is used to convey the process gas into the reaction cavity. However, for some process gases (for example, mixed gas containing SiH4 and O2), solid by-products (such as SiO2 particles) may be generated under certain conditions. If such process gas is conveyed in one conveying pipe for a long time, the gas may pre-react in the pipeline, and the particles generated by the reaction may be deposited on the wall of the gas conveying pipe, gradually forming a blockage, which may reduce the working efficiency of the equipment and affect the quality of the thin film deposited on the wafer surface for a long time. SUMMARY

[0009] The technical problem solved by the present application is to provide a plasma enhanced chemical vapor deposition device which can open the chamber door without damaging the vacuum environment in the reaction chamber, so as to overcome the shortcomings of the prior art.

[0010] To solve the above technical problems, the present application adopts the following technical solutions:

[0011] The plasma enhanced chemical vapor deposition device comprises a reaction chamber, a heating disc arranged in the reaction chamber, a gas distribution plate arranged above the heating disc in the reaction chamber, a conductive cover cap covering the gas distribution plate to form a buffer gas cavity inside, the cover cap has a gas inlet interface, the device further comprises a radio frequency generating device electrically connected with the gas inlet interface, the reaction chamber has a chamber door on the side, the reaction chamber further has a first vacuum exhaust port, the first vacuum exhaust port is connected with a vacuum pump through a first exhaust pipe, the first exhaust pipe has a first control valve, characterized in that: a transfer chamber covering the chamber door is further arranged outside the reaction chamber, an electric fork lift for sending or taking out a wafer from the reaction chamber is arranged in the transfer chamber, a placing port is arranged above the initial resting position of the electric fork lift on the top of the transfer chamber, a sealing cover plate is arranged on the placing port, the transfer chamber further has a second vacuum exhaust port and an atmospheric communication port, the second vacuum exhaust port is connected with the vacuum exhaust device through a second exhaust pipe, the atmospheric communication port is connected with the atmosphere through an atmospheric communication pipe, the second exhaust pipe has a second control valve, and the atmospheric communication pipe has a third control valve.

[0012] By adopting the above technical solutions, the transfer chamber is arranged, the transfer chamber can be vacuumized before the chamber door is opened, a vacuum environment is created for the transfer chamber, the chamber door is opened without damaging the vacuum environment in the reaction chamber, and the substances harmful to the wafer surface vapor deposition in the air are not input into the reaction chamber, so as to ensure the quality of the subsequent wafer surface vapor deposition. After the chamber door is opened, the electric fork lift can put the wafer which has not been deposited into the reaction chamber or take out the deposited wafer from the reaction chamber.

[0013] In the specific embodiment of the present application, a first sensor for sensing whether the wafer exists is arranged below the initial resting position of the electric fork lift in the transfer chamber.

[0014] In the specific embodiment of the present application, the electric fork lift comprises a driving base, a sliding plate arranged on the driving base, and a fork lift connected in front of the sliding plate, the rear end of the driving base has a second sensor, and the tail end of the sliding plate has a sensed piece which can be sensed by the second sensor.

[0015] In the specific embodiment of the present application, a vacuum gauge and a vacuum switch are arranged in the conveying cavity. The vacuum gauge is used to detect the vacuum degree in the conveying cavity in real time, and the vacuum switch is used to detect whether the atmospheric pressure is reached in the conveying cavity.

[0016] In the further improvement of the present application, a mixing cavity is further arranged above the reaction cavity, the mixing cavity is provided with an air inlet and an air outlet, the air inlet of the mixing cavity is connected with a first air pipe, the first air pipe is further connected with a second air pipe at a position close to the air inlet, and the air outlet of the mixing cavity is connected with the air inlet interface. By using the technical solution, the two kinds of gases to be pre-reacted are respectively conveyed to the mixing cavity through the first air pipe and the second air pipe, and finally mixed in the mixing cavity. Thus, the problem of clogging the air pipe does not exist before mixing. Although a small amount of mixed gas exists in the first air pipe close to the air inlet, the mixing time is extremely short before entering the mixing cavity, and the accumulation generated by the reaction does not occur, so that the clogging phenomenon does not occur.

[0017] In the specific embodiment of the present application, the air inlet interface is connected with a conductive lower connecting pipe penetrating out of the reaction cavity, the air outlet is connected with an upper connecting pipe, the upper connecting pipe and the lower connecting pipe are connected through an insulating pipe, and the radio frequency generating device is connected to the lower connecting pipe through a wire. By the blocking of the insulating pipe, the radio frequency generating device can only act on the conductive cover and the gas distribution disc to form the plasma, but the radio frequency electric field cannot be conducted to the mixing cavity and the first air pipe and the second air pipe.

[0018] In the specific embodiment of the present application, the heating disc is provided with a top pin capable of extending upward from the inside of the heating disc.

[0019] In the specific embodiment of the present application, a shielding cover covering the reaction cavity and the mixing cavity is further included, and the first air pipe and the second air pipe penetrate out of the shielding cover.

[0020] By using the above technical solution, the present application forms a conveying cavity capable of forming a vacuum condition, so that when the cavity door of the reaction cavity is opened, the conveying cavity is also in a vacuum state, that is, the cavity door is in a vacuum environment. In this case, the cavity door has the following advantages:

[0021] 1. The vacuum state in the reaction cavity is not damaged, the vacuum pump is not frequently started to reduce the burden of the vacuum system, and the influence on the deposition rate and the film quality is reduced;

[0022] 2. It is beneficial to maintain the stability of the radio frequency power glow discharge, reduce the density fluctuation of the plasma, and improve the chemical reaction rate and the film uniformity;

[0023] 3. When the cavity door is opened, the inside of the reaction cavity is not directly communicated with air, so that the risk of wafer pollution in the reaction cavity by particles can be reduced.

[0024] 4. The temperature, pressure and other parameters in the reaction cavity can be stably controlled.

[0025] Therefore, the present application has the advantages of not breaking the vacuum environment in the reaction cavity and avoiding pollution in the reaction cavity when the cavity door of the reaction cavity is opened, and the quality of vapor deposition on the wafer surface can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic view of the three-dimensional structure of the present application;

[0027] Figure 2 is a schematic view of the partial three-dimensional structure of the present application after the shielding cover is removed;

[0028] Figure 3 is a schematic view of the outside of the reaction cavity;

[0029] Figure 4 is a schematic view of the inside of the reaction cavity after being cut open;

[0030] Figure 5 is a schematic view of the inside parts and mechanisms of the transfer cavity;

[0031] Figure 6 is a schematic view of the structure of the gas distribution plate. DETAILED DESCRIPTION

[0032] As shown in Figure 1 and Figure 2 , the plasma enhanced chemical vapor deposition equipment of the present application comprises a reaction cavity 100, a mixing cavity 200 and a transfer cavity 300. The reaction cavity 100 and the transfer cavity 300 are both arranged on the top of a cabinet 400.

[0033] Among them, as shown in Figure 3 and Figure 4 , the reaction cavity 100 is provided with a heating plate 110, a gas distribution plate 120 and a cover 130. The gas distribution plate 120 is arranged above the heating plate 110, and there is a gap between the heating plate 110 and the gas distribution plate 120. In combination with Figure 6As shown, the gas distribution plate 120 is uniformly provided with a plurality of gas distribution holes 121. The cover 130 covers the gas distribution plate 120 to form a buffer gas cavity 140 inside. The reaction cavity 100, the gas distribution plate 120 and the cover 130 are all made of aluminum. The cover 130 is provided with a gas inlet interface 131 at the middle position. A circular baffle 141 is fixed in the buffer gas cavity 140 below the gas inlet interface 131. The baffle 141 has the function of diffusing the incoming process gas to the surrounding of the cavity. The gas inlet interface 131 is extended upward outside the reaction cavity 100 through a conductive lower connector 132. The reaction cavity 100 is further provided with a programmed reaction cavity door 101 at the side. In the embodiment, the reaction cavity door 101 is a pneumatic cavity door, but it can also be an electric cavity door.

[0034] The bottom of the reaction cavity 100 is provided with a first vacuum gas outlet 150, which is connected to a vacuum pump (not shown) through a first gas outlet pipe 151 inside the cabinet 400. The first gas outlet pipe 151 is provided with a first control valve. A first vacuum gauge is arranged in the reaction cavity 100 to detect the vacuum degree in the reaction cavity in real time.

[0035] Furthermore, the heating plate 110 is provided with a plurality of top pins 111 which can be programmed to extend upward from the inside of the heating plate 110. In the embodiment, the top pins 111 are pneumatic top pins, but they can also be driven in other ways, such as electric top pins. Specifically, the cylinders of the pneumatic top pins are fixed below the outside of the reaction cavity 100, and the piston rods of the pneumatic top pins are sealingly passed through the bottom plate of the reaction cavity and connected to the top pins 111 through supports 111a.

[0036] Further Figure 2 and in combination Figure 4As shown, the mixing chamber 200 is made of aluminum and is arranged above the reaction chamber 100. The mixing chamber 200 has a gas inlet at the top and a gas outlet at the bottom. The first gas pipe 211 is connected to the gas inlet, and the upper pipe 213 connected to the lower pipe 132 is arranged downwardly in the gas outlet. The second gas pipe 212 is connected to the first gas pipe 211 near the gas inlet. With such a structure, the two gases to be reacted are respectively delivered to the mixing chamber 200 through the first gas pipe 211 and the second gas pipe 212, and finally mixed in the mixing chamber 200 to form the process gas. Thus, there is no problem of clogging the gas pipe before mixing. Although there is a small amount of mixed gas near the gas inlet of the first gas pipe 211, the mixing time is very short before entering the mixing chamber, and the accumulation of reaction products does not occur, so that the clogging phenomenon does not occur. For example, the first gas pipe 211 can deliver oxygen or a mixed gas containing oxygen alone (the other gas in the mixed gas does not react with oxygen), and the second gas pipe can deliver SiH4 or a mixed gas containing SiH4 alone (the other gas in the mixed gas does not react with SiH4).

[0037] In the present embodiment, the first gas pipe 211, the second gas pipe 212, and the lower pipe 132 are made of 316L stainless steel. The upper pipe 213 is an insulating pipe. In the present embodiment, the material of the upper pipe 213 is PFA, which has corrosion resistance in addition to the insulating property.

[0038] In this embodiment, a mounting port is provided at the top of the reaction chamber 100. A mounting plate 160 is sealed over this mounting port. The mounting plate 160 is also made of aluminum. The mounting plate 160 has a central hole, on which an insulating flange 161 is sealed and mounted. In this embodiment, the flange 161 is a ceramic disc, possessing high-temperature resistance and insulation properties, preventing electrical conduction to the reaction chamber 100. Three stepped holes 170 are evenly spaced around the central hole along a circular axis on the mounting plate 160. Each of the three stepped holes 170 is provided with an adjusting bolt 171. The head of the adjusting bolt 171 is located above the stepped hole, and the screw passes downwards through the mounting plate 160. The end face of the head has a hexagonal countersunk hole or a slotted groove for easy insertion of a special tool for turning. A cover 130 is provided below each of the three stepped holes 170, with threaded through holes 131 respectively. The screw end of the adjusting bolt 171 is threadedly connected to the threaded through hole 131. In this embodiment, the adjusting bolt 171 is made of ceramic, providing high-temperature insulation and preventing electrical conduction to the reaction chamber 100. A sealing nut 172 is also provided in the stepped hole 170. The sealing nut 172 seals the stepped hole 170, preventing gas leakage from the gap between the adjusting bolt 171 and the stepped hole 170. The sealing nut 172 is also made of aluminum. As is well known, the sealing between the above-mentioned parts can be achieved using high-temperature resistant sealing rings.

[0039] With this structure, the height and level of the gas distribution plate 120 relative to the heating plate 110 can be easily adjusted by turning the adjusting bolts in each stepped hole 170. This ensures that the plasma is effectively deposited on the wafer and that the plasma deposition is uniform, thus helping to ensure the quality of wafer deposition.

[0040] A radio frequency generator 220 is also provided next to the mixing chamber 200. The output terminal of the radio frequency generator 200 is electrically connected to the lower pipe 132.

[0041] In addition, a shielding cover 230 is fixed to the top of the mixing chamber 200, covering the mixing chamber 200 and the radio frequency generator 220. The first gas supply pipe 211 and the second gas supply pipe 212 extend out from the shielding cover. The shielding cover 230 can shield the electromagnetic radiation generated when the equipment is working, avoiding pollution to the environment.

[0042] like Figure 1 and Figure 5 As shown, the transfer chamber 300 is also made of aluminum, located on the side of the reaction chamber 100 and sealed on the reaction chamber door 101. An electric fork 310 for feeding or removing wafers into or from the reaction chamber is installed inside the transfer chamber 100.

[0043] The electric fork 310 comprises a driving base 311 fixed in the conveying cavity 300, a sliding plate 311 arranged on the driving base 311 and driven by the driving base 311, and a fork 313 connected to the front of the sliding plate 311. The driving base 311 is driven by a motor to drive the sliding plate to move forward and backward along the guide rail on the base to realize the forward and backward movement of the fork, thereby realizing the conveying of the wafer into the reaction cavity 100 or the taking out of the wafer from the reaction cavity 100.

[0044] A placing port 301 is arranged above the initial staying position of the fork 313 on the top of the conveying cavity 300, and a sealing cover plate 302 is arranged on the placing port 301. A glass window 303 is further arranged on the sealing cover plate 302.

[0045] The conveying cavity 300 is provided with a second vacuum exhaust port 320 and an atmospheric communication port 330. The second vacuum exhaust port 320 is communicated with a vacuum pump through a second exhaust pipe 321 arranged inside the cabinet 100. The atmospheric communication port 330 is communicated with the atmosphere through an atmospheric communication pipe 331 arranged inside the cabinet 100. The second exhaust pipe 321 is provided with a second control valve, and the atmospheric communication pipe 331 is provided with a third control valve.

[0046] In the embodiment, a first sensor 322 for sensing whether the wafer exists is arranged below the initial staying position of the fork 313 in the conveying cavity 300. The rear end of the driving base 311 is provided with a second sensor 323, and the tail end of the sliding plate 311 is provided with a sensed piece 323a which can be sensed by the second sensor 323. When the sensed piece 323a is sensed by the second sensor 323, it indicates that the fork 313 is located at the initial staying position, i.e. the position directly below the placing port 301.

[0047] The conveying cavity 300 is further provided with a second vacuum gauge 304 and a vacuum switch 305. The vacuum gauge 304 is used for detecting the vacuum degree in the conveying cavity 300 in real time, and the vacuum switch 305 is used for detecting whether the atmospheric pressure is reached in the conveying cavity 300.

[0048] In the present application, the above-mentioned radio frequency generating device 220, the heating disc 110, the first control valve, the second control valve, the third control valve, the reaction cavity door 101, the driving base 311, the ejector pin 111, the first sensor 322, the second sensor 323, the first vacuum gauge, the second vacuum gauge 304 and the vacuum switch 305 are connected to the computer 500 through transmission lines. In the present application, the computer 500 acquires signals or data from the first sensor 322, the second sensor 323, the first vacuum gauge, the second vacuum gauge 304 and the vacuum switch 305, and can control the work of the radio frequency generating device 220, the heating disc 110, the first control valve, the second control valve, the third control valve, the reaction cavity door 101, the driving base 311 and the ejector pin 111,

[0049] The above is the plasma enhanced chemical vapor deposition device of the present application, and its working mode is as follows:

[0050] The reaction cavity 100 is in vacuum state during working, and the general gas and special gas delivered by the first gas delivery pipe 211 and the second gas delivery pipe 212 are mixed in the mixing cavity 200 to form process gas, which is then delivered into the buffer cavity 140. The radio frequency generating device 220 provides the uniform gas disc 120 and the cover 130 with radio frequency power source of set power, so that the process gas in the buffer cavity 140 forms plasma, which is sprayed on the wafer heated by the lower heating disc 100 through the uniform gas spray hole 121 on the uniform gas disc 120, and then the thin film is deposited on the wafer surface. The vacuum state in the reaction cavity 100 is formed and closed by controlling the opening and closing of the first control valve through the computer 500.

[0051] The wafer is delivered into the reaction cavity 100 and taken out from the reaction cavity 100, both of which need to make the delivery cavity 300 in vacuum state, specifically, in the case that the sealing cover plate 302 of the delivery cavity 300 is closed, the second control valve is opened, so that the vacuum pump pumps the delivery cavity 300, the second vacuum gauge 304 detects the vacuum degree in the delivery cavity 300 in real time, and the computer program compares the difference between the vacuum degree in the reaction cavity 100 and the vacuum degree in the delivery cavity 300, when the difference is within the set threshold range, the computer program controls the reaction cavity door 101 to open (if the difference is not within the threshold range, the computer program 101 will not control the reaction cavity door to open), and then controls the electric fork 310 to deliver the wafer into the reaction cavity 100 or take the wafer out from the reaction cavity 100.

[0052] In the case that the reaction cavity door 101 is closed, the second control valve is closed and the third control valve is opened, so that the delivery cavity 300 is connected with the atmosphere, and the vacuum state of the delivery cavity 300 is broken, and then the wafer can be placed on the fork 313 in the initial resting position or taken out by opening the top sealing cover plate 302.

[0053] In the present application, the electric fork 310 needs to control the ejector pin 111 to lift up when placing or taking off the wafer from the heating disc 110, and the specific way is as follows: when placing the wafer on the heating disc 110, first control the electric fork 310 to send the wafer to the upper side of the heating disc 110, then the ejector pin 111 lifts up from the lower side until the wafer is lifted up and separated from the electric fork 310, and then control the electric fork 310 to retreat and exit the reaction cavity. After the fork 313 of the electric fork 310 leaves the upper side of the heating disc 110, control the ejector pin 111 to drop until the wafer completely falls on the surface of the heating disc 110. When taking off the wafer from the heating disc, first control the ejector pin 111 to lift up and lift the wafer to separate from the surface of the heating disc 110, then control the electric fork 310 to enter the reaction cavity and make the fork 310 located below the wafer, then control the ejector pin 111 to drop and make the wafer fall on the fork 310, and finally control the electric fork 310 to retreat and exit the reaction cavity with the wafer, and transfer the wafer to the transfer cavity 300.

[0054] The above is the detailed introduction of the present application, and through the above detailed introduction, it can be seen that the present application has the advantages that by setting the transfer cavity capable of forming a vacuum condition, the transfer cavity is controlled to be in a vacuum state when the cavity door of the reaction cavity is opened, that is, the inside and outside of the cavity door are in a vacuum environment, and the cavity door has the following advantages when it is opened in this case:

[0055] 1. The vacuum state in the reaction cavity is not broken, the vacuum pump is not frequently started to reduce the burden of the vacuum system, and the influence on the deposition rate and the film quality is reduced;

[0056] 2. It is beneficial to maintain the stability of the glow discharge of the radio frequency power supply, reduce the density fluctuation of the plasma, and improve the chemical reaction rate and the film uniformity;

[0057] 3. When the cavity door is opened, the inside of the reaction cavity is not directly communicated with the air, and the risk of wafer pollution by particles in the reaction cavity is reduced.

[0058] 4. It is beneficial to the stable control of the temperature, pressure and other parameters in the reaction cavity.

[0059] Therefore, the present application has the advantages that the cavity door of the reaction cavity is not broken when it is opened, and the cavity is not polluted, and it is beneficial to improve the quality of the wafer surface vapor deposition.

Claims

1. A plasma enhanced chemical vapor deposition apparatus, comprising a reaction chamber, a heating disc arranged in the reaction chamber, a gas distribution disc arranged in the reaction chamber above the heating disc, an electrically conductive cover cap covering the gas distribution disc to form a buffer gas cavity inside, the cover cap having a gas inlet interface, further comprising a radio frequency generating device electrically connected to the gas inlet interface, the reaction chamber having a reaction chamber door on the side, the reaction chamber further having a first vacuum exhaust port, the first vacuum exhaust port being connected to a vacuum pump through a first exhaust pipe, the first exhaust pipe having a first control valve, characterized in that: The reaction cavity is further provided with a transfer cavity which covers the furnace door, the transfer cavity is provided with an electric fork which sends or takes out the wafer from the reaction cavity, the top of the transfer cavity is provided with a placing opening above the initial stop position of the electric fork, the placing opening is provided with a sealing cover plate, the transfer cavity is further provided with a second vacuum exhaust opening and an atmospheric communication opening, the second vacuum exhaust opening is connected with the vacuum device through a second exhaust pipe, the atmospheric communication opening is connected with the atmosphere through an atmospheric communication pipe, the second exhaust pipe is provided with a second control valve, and the atmospheric communication pipe is provided with a third control valve.

2. The plasma-enhanced chemical vapor deposition apparatus of claim 1, wherein: The transfer cavity is provided with a first sensor below the initial stop position of the electric fork to sense whether the wafer exists.

3. The plasma-enhanced chemical vapor deposition apparatus of claim 1, wherein: The electric fork comprises a driving base, a sliding plate arranged on the driving base, and a fork connected in front of the sliding plate, the rear end of the driving base is provided with a second sensor, and the tail end of the sliding plate is provided with a sensed piece which can be sensed by the second sensor.

4. The plasma-enhanced chemical vapor deposition apparatus of claim 1, wherein: The transfer cavity is provided with a vacuum gauge and a vacuum switch.

5. The plasma-enhanced chemical vapor deposition apparatus of claim 1, wherein: The upper part of the reaction cavity is further provided with a mixing cavity, the mixing cavity is provided with an air inlet and an air outlet, the air inlet of the mixing cavity is connected with a first air supply pipe, the first air supply pipe is further connected with a second air supply pipe near the air inlet, and the air outlet of the mixing cavity is connected with the air inlet interface.

6. The plasma-enhanced chemical vapor deposition apparatus of claim 5, wherein: The air inlet interface is connected with a lower connecting pipe which penetrates the reaction cavity and is conductive, and the air outlet is connected with an upper connecting pipe which is connected with the lower connecting pipe and is insulating, the radio frequency generating device is connected with the lower connecting pipe through a wire.

7. The plasma-enhanced chemical vapor deposition apparatus of claim 1, wherein: The heating disc is provided with a top pin which can be extended upward from the inside of the heating disc.

8. The plasma-enhanced chemical vapor deposition apparatus of claim 5, wherein: The shielding cover which covers the reaction cavity and the mixing cavity is further provided, and the first air supply pipe and the second air supply pipe penetrate the shielding cover.

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