Chemical vapor deposition equipment

Abstract

The utility model relates to the technical field of chemical vapor deposition, in particular to chemical vapor deposition equipment. The chemical vapor deposition equipment comprises a reaction cavity and a reaction table arranged in the reaction cavity, the reaction cavity comprises a gas inlet cavity used for being connected with a gas inlet pipeline, the gas inlet cavity is provided with a center cavity communicated with the space where the reaction table is located, and the gas inlet cavity is provided with a gas inlet channel allowing reaction gas in the gas inlet pipeline to enter the center cavity. The gas inlet cavity comprises an inner ring and an outer ring, the gas inlet channel comprises an annular gas cavity defined by the outer wall of the inner ring and the inner wall of the outer ring, a gas inlet formed in the outer ring and gas distribution holes formed in the inner ring, the gas inlet is communicated with the annular gas cavity so that reaction gas can enter the annular gas cavity, and the annular gas cavity is communicated with the center cavity through the gas distribution holes. The reaction gas can be diffused and buffered in the annular gas cavity, so that the mixing uniformity of various gas components in the reaction gas is improved, and the reaction efficiency and quality are further improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to chemical vapor deposition technical field, concretely relates to a chemical vapor deposition equipment. BACKGROUND

[0002] Microwave plasma chemical vapor deposition (MPCVD) method is the first choice method for preparing high-quality single crystal diamond, and the principle of MPCVD growth of diamond is as follows: a microwave source emits microwave energy, which is transmitted through a waveguide and converted by an antenna mode into a resonant cavity, and a microwave alternating electric field of a certain intensity is formed in the resonant cavity; under the excitation of the alternating electric field, the reaction gas maintained in a low pressure state is broken down to form a plasma; various active groups in the plasma undergo a series of chemical reactions on the surface of the diamond seed crystal, and gradually undergo adsorption, desorption, migration, diffusion and other dynamic processes on the surface of the diamond seed crystal to finally become an atomic-level deposition layer; the carbon atom deposition layer grows in layers, and after a long time of continuous growth, a diamond crystal is finally obtained.

[0003] The basic structure of the existing MPCVD equipment can be seen from the MPCVD equipment disclosed in the Chinese utility model patent with the authorization announcement number CN219156975U, the resonant cavity is a reaction cavity, the resonant cavity includes a cavity body, a bottom plate, a top cover, a sealing flange, the top cover is connected at the top end of the cavity body through screws, the center of the top cover is provided with an observation window, the observation window is provided with a window flange, the window flange is connected with the sealing flange through screws, and the metal clamping wire mesh quartz piece is clamped and fixed between the window flange and the sealing flange. A growth base is arranged in the reaction cavity, and the growth base forms a reaction table, the growth base is supported on the bottom plate through a compression ring, a substrate table is arranged on the growth base, and a seed crystal is arranged on the substrate table.

[0004] The single crystal diamond sheet is placed on the molybdenum substrate table during the cultivation process, and the substrate table is in thermal conduction with the growth base to reasonably control the growth temperature of the single crystal diamond sheet. Special gases such as hydrogen, methane, oxygen and nitrogen need to be introduced into the single crystal diamond sheet during the cultivation process, that is, reaction gases used for reaction on the surface of the seed crystal, the observation window of the top cover is provided with a special gas inlet hole, the inlet hole is connected with the corresponding gas pipeline, and the special gas enters the inside of the reaction cavity through the inlet hole of the top cover and reacts with the single crystal diamond sheet on the substrate table. The observation window of the top cover and the quartz piece covering the window are used to form an air inlet cavity located at the top of the reaction cavity, the air inlet cavity has a central cavity corresponding to the growth base below, the central cavity is part of the internal cavity of the reaction cavity, and the inlet hole forms an air inlet channel for the external gas pipeline to communicate with the central cavity.

[0005] Since high-quality single crystal diamond growth requires special growth environment, higher requirements are put forward for the function of MPCVD equipment. The special gas required during single crystal diamond growth has a great influence on the quality and efficiency of synthesis, so reasonable gas passage design and control of the way of inputting special gas into the reaction chamber are particularly important for efficient preparation of high-quality single crystal diamond, and the uniformity of mixed gas will affect the quality and efficiency of synthesis. At present, various gases required for growth are collected through branch pipes into the main pipe near the reaction chamber, the main pipe is connected with the gas inlet hole, and various gases are mixed in the main pipe and then introduced into the reaction chamber through the gas inlet hole. Since the mixing effect of various gases in the main pipe is limited and is limited by the length of the main pipe, the uniformity of gas mixing is not good enough, which affects the reaction efficiency and quality. Practical new type content

[0006] The utility model discloses a chemical vapor deposition equipment, to solve the problem of the chemical vapor deposition equipment of current use to the reaction gas mixed uniformity not enough in the reaction chamber is unfavorable to the reaction efficiency and quality.

[0007] The technical scheme of the chemical vapor deposition equipment of the utility model is:

[0008] A kind of chemical vapor deposition equipment, including reaction chamber and reaction platform placed in reaction chamber, reaction chamber includes the gas inlet cavity for connecting external gas inlet pipe, gas inlet cavity has with the central cavity of the space of reaction platform intercommunication, gas inlet cavity is equipped with the gas inlet passage of the reaction gas in the gas inlet pipe into central cavity, gas inlet cavity includes inner ring and outer ring, the inner wall of inner ring is used to form the inner wall of at least a part of central cavity, gas inlet passage includes annular gas cavity surrounded by inner ring outer wall and outer ring inner wall and the gas inlet on the outer ring, gas distribution hole is arranged on inner ring, gas inlet is communicated with annular gas cavity to make reaction gas enter annular gas cavity, gas distribution hole communicates annular gas cavity with central cavity.

[0009] Beneficial effect: the utility model improves on the basis of the chemical vapor deposition equipment in prior art, sets up inner ring and outer ring to be set up structure for gas inlet cavity, utilizes the annular gas cavity surrounded by inner ring outer wall and outer ring inner wall, sets up gas inlet on the outer ring, sets up gas distribution hole on inner ring, utilizes gas inlet, annular gas cavity, gas distribution hole to form gas inlet passage, when reaction gas in external gas inlet pipe enters the central cavity of gas inlet cavity through gas inlet passage, reaction gas first enters annular gas cavity through gas inlet, then enters central cavity from annular gas cavity through gas distribution hole, can utilize the space change of gas inlet, annular gas cavity, gas distribution hole, disturb the airflow of reaction gas, reaction gas can diffuse, buffer in annular gas cavity, it is favorable to improve the mixing uniformity of various gas components in reaction gas, and then improve reaction efficiency and quality.

[0010] Further, the size of the annular air cavity in the inner ring axial direction is greater than the size of the air distribution hole in the inner ring axial direction.

[0011] Further, the size of the annular air cavity in the outer ring axial direction is greater than the size of the air inlet in the outer ring axial direction.

[0012] Further, the air distribution hole is provided with a plurality of circumferential air distribution holes on the inner ring, and the center lines of the air distribution holes are coplanar.

[0013] Further, the inner wall of the outer ring is provided with an inner step, the end of the inner ring abuts on the inner step, the outer wall of the inner ring is provided with an outer step, and the outer step is opposite to the inner step in the inner ring axial direction to form the annular air cavity between the outer step and the inner step.

[0014] Further, the air inlet cavity body comprises a gland for cooperating with the inner ring and the outer ring to form the central cavity, the gland presses the inner ring on the inner step, the inner ring and the outer ring are provided with pressing surfaces matched with the gland, and the pressing surfaces are provided with sealing pads for being pressed by the gland to form a seal.

[0015] Further, the air inlet cavity body comprises a gland for cooperating with the inner ring and the outer ring to form the central cavity, the inner ring and the outer ring are provided with pressing surfaces matched with the gland, the end of the inner ring away from the side where the reaction table is located is provided with an outer wall surrounding a sealing groove connected with the pressing surface, and a sealing ring is arranged in the sealing groove, and the sealing ring is pressed in the sealing groove to form a seal when the gland presses the inner ring and the outer ring.

[0016] Further, the outer ring is provided with a radial air inlet hole, the air inlet hole constitutes the air inlet, the air distribution hole is a through hole penetrating the inner wall and the outer wall of the inner ring, and the diameter of the air inlet hole is greater than the diameter of the air distribution hole.

[0017] Further, the reaction cavity comprises a top cover and a main body part surrounding the internal space of the reaction cavity, the top cover comprises a main cover body and the air inlet cavity body, the air inlet cavity body is detachably connected to the main cover body, and the main cover body is fixed to the main body part of the reaction cavity.

[0018] Further, the air inlet cavity body comprises a gland for cooperating with the inner ring and the outer ring to form the central cavity and a fixing flange for pressing the gland on the inner ring and the outer ring, the main cover body is provided with a mounting flange matched with the outer ring, and the fixing flange, the outer ring and the mounting flange are provided with corresponding connecting holes for connecting bolts to enable the air inlet cavity body to be fixed on the main cover body through the bolts. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a cross-sectional structure schematic view of an embodiment of the chemical vapor deposition equipment of the utility model;

[0020] Figure 2 It is a schematic view of the top cover in Figure 1 ​

[0021] Figure 3 For Figure 2 a schematic view of the gas inlet channel.

[0022] In the figure: 1, top cover; 10, main cover body; 101, disc body; 102, mounting flange; 103, threaded hole; 11, outer ring; 111, gas inlet interface; 112, gas inlet hole; 113, inner step; 12, inner ring; 121, gas distribution hole; 122, outer step; 13, gland; 14, fixing flange; 15, first sealing flat gasket; 16, second sealing flat gasket; 17, third sealing flat gasket; 18, sealing ring; 19, annular air cavity; 110, central cavity; 2, main cavity body; 3, bottom plate; 4, growth base; 5, substrate base. DETAILED DESCRIPTION

[0023] The basic concept of the chemical vapor deposition equipment of the utility model is that the reaction gas first enters the annular air cavity through the gas inlet, and then enters the inside of the reaction cavity body through the gas distribution hole. The reaction gas can diffuse and buffer in the annular air cavity, which is conducive to improving the mixing uniformity of various gas components in the reaction gas, and further improving the reaction efficiency and quality.

[0024] The utility model will be specifically described in combination with the following embodiments.

[0025] Embodiments of the chemical vapor deposition equipment of the utility model:

[0026] As Figure 1 , Figure 2 , Figure 3 shown, the chemical vapor deposition equipment includes a reaction cavity and a reaction base placed in the reaction cavity. The chemical vapor deposition equipment in the embodiment is an MPCVD equipment, which is used for cultivating single crystal diamond. The reaction cavity includes a top cover 1, a main cavity body 2, and a bottom plate 3. The top cover 1 is fixed on the upper end of the main cavity body 2, and the bottom plate 3 is fixed on the lower end of the main cavity body 2. The reaction base is a growth base 4, which is supported on the bottom plate 3. A substrate base 5 is placed on the growth base 4, and the substrate base 5 is used for placing a single crystal diamond seed wafer. The top cover 1, the main cavity body 2, and the bottom plate 3 enclose a closed cavity space of the reaction cavity, and the substrate base 5 is located in the reaction cavity. By introducing special gas required for cultivating single crystal diamond into the reaction cavity and inputting microwaves, the single crystal diamond seed wafer is synthesized and grown by using the chemical vapor deposition method.

[0027] The top cover 1 comprises a main cover body 10 fixed on the top of the main cavity 2 and an air inlet cavity fixed on the top of the main cover body 10. The air inlet cavity is located on the top of the reaction cavity and is used to connect an external air inlet pipeline for inputting special gas into the reaction cavity. The special gas is a reaction gas required by chemical vapor deposition. The air inlet cavity has a central cavity 110 in communication with a space where the growth pedestal 4 is located. The central cavity 110 corresponds to the growth pedestal 4 in up-down direction. The air inlet cavity is provided with an air inlet passage for the reaction gas in the air inlet pipeline to pass into the central cavity 110.

[0028] During the cultivation process of the single crystal diamond, special gases such as hydrogen, methane, oxygen and nitrogen need to be input. The various gases are collected into a main pipeline through different branch pipelines. The main pipeline forms the external air inlet pipeline. The main pipeline is connected with the air inlet cavity. After the various gases are premixed in the main pipeline, they enter the cavity space of the reaction cavity through the air inlet passage of the air inlet cavity. The uniformity of the mixed gas affects the synthesis quality and efficiency of the single crystal diamond.

[0029] In order to improve the uniformity of the mixed gas, a cavity for re-mixing is arranged in the air inlet passage. Specifically, the air inlet cavity comprises an inner ring 12 and an outer ring 11. An inner wall of the inner ring 12 is used to form part of an inner wall of the central cavity 110. The air inlet passage comprises an annular cavity 19 surrounded by the outer wall of the inner ring 12 and the inner wall of the outer ring 11, an air inlet port arranged on the outer ring 11 and a gas distribution hole 121 arranged on the inner ring 12. The air inlet port is an air inlet hole 112. The air inlet hole 112 is in communication with the annular cavity 19 to allow the reaction gas to enter the annular cavity 19. The gas distribution hole 121 is in communication between the annular cavity 19 and the central cavity 110. In this way, the air inlet cavity is arranged in a structure of the inner ring 12 and the outer ring 11. The air inlet passage is formed by the air inlet hole 112, the annular cavity 19 and the gas distribution hole 121. When the reaction gas in the external air inlet pipeline enters the central cavity 110 of the air inlet cavity through the air inlet passage, the reaction gas first enters the annular cavity 19 through the air inlet hole 112 and then enters the central cavity 110 from the annular cavity 19 through the gas distribution hole 121. The space changes of the air inlet hole 112, the annular cavity 19 and the gas distribution hole 121 can disturb the airflow of the reaction gas. The reaction gas is premixed once in the main pipeline and then diffused and buffered in the annular cavity 19 after passing through the air inlet hole 112. The annular cavity 19 forms a secondary mixing cavity, which is beneficial to improve the mixing uniformity of the gas components in the reaction gas and further improve the reaction efficiency and quality.

[0030] In this embodiment, the special gas required by the chemical vapor deposition process enters the inside of the reaction cavity through the top cover 1, the gas enters the central cavity 110 of the gas inlet cavity from the radial side of the top cover 1, and changes to a downward airflow direction through the central cavity 110, so that the airflow flows downward and directly against the substrate table 5, which is beneficial to the synthesis quality, synthesis efficiency and plasma spherical shape of the single crystal diamond. In other embodiments, a mounting port can be provided on the sidewall or bottom plate of the main cavity, and the gas inlet cavity is mounted at the mounting port on the sidewall or bottom plate of the main cavity.

[0031] The reaction cavity is in a cylindrical shape, the inner diameter of the main cavity 2 is larger than the inner diameter of the central cavity 110, the main cover 10 is fixed on the upper end of the main cavity 2 by bolts, the main cover 10 includes a disc body 101 and a cylinder body located at the center of the disc body 101, the lower end of the cylinder body is integrally connected with the disc body 101, and the upper end of the cylinder body is provided with a mounting flange 102, the gas inlet cavity is fixed on the mounting flange 102, and the central cavity 110 is communicated with the space below the substrate table 5 through the inner cavity of the cylinder body.

[0032] The axial direction of the inner ring 12 and the outer ring 11 of the gas inlet cavity is the up-down direction, the inner wall of the outer ring 11 is provided with an upward inner step 113, the lower end of the inner ring 12 abuts against the inner step 113, the outer wall of the inner ring 12 is provided with a downward outer step 122, the outer ring 11 is coaxially arranged on the outside of the inner ring 12, and the outer step 122 is opposite to the inner step 113 in the up-down direction to form an annular gas cavity 19 between the outer step 122 and the inner step 113, which is convenient for processing and beneficial to forming the annular gas cavity 19 with a larger space. In other embodiments, a ring groove can be provided on the outer wall of the inner ring, and the ring groove and the inner wall of the outer ring are used to form the annular gas cavity. In other embodiments, a ring groove can be provided on the inner wall of the outer ring, and the ring groove and the outer wall of the inner ring are used to form the annular gas cavity.

[0033] The gas inlet cavity further includes a gland 13 for cooperating with the inner ring 12 and the outer ring 11 to form the central cavity 110, the gland 13 can press the inner ring 12 against the inner step 113, the inner ring 12 and the outer ring 11 are provided with pressing surfaces matched with the gland 13, the pressing surfaces are provided with sealing pads for being pressed by the gland 13 to form a seal, and the inner ring 12 is pressed in the outer ring 11 by the gland 13, which is convenient for disassembly and assembly and guarantees the sealing property in cooperation with the sealing pads. In other embodiments, threads matched with each other can be provided on a part of the outer wall of the inner ring and the inner wall of the outer ring, so that the inner ring is threadedly connected in the outer ring, and at this time the gland is only pressed against the outer ring and sealed. In other embodiments, the gland and the inner ring can be integrally connected, and the gland is pressed against the outer ring and sealed.

[0034] In this embodiment, the gas inlet cavity of the top cover 1 is also used to form an observation window, the gland 13 is made of transparent glass sheet, which can facilitate observation while sealing the central cavity 110. The gas inlet cavity further comprises a fixing flange 14 for pressing the gland 13 against the inner ring 12 and the outer ring 11, so as to fix the gland 13, and the fixing flange 14 is sealed with the gland 13. In other embodiments, when the window observation is not relied on, the gland, the fixing flange and the inner ring can be arranged in an integrated structure.

[0035] In this embodiment, the outer ring 11 is fixedly connected with the mounting flange 102 of the main cover body 10 by bolts, the main cover body 10, the main cavity 2 and the bottom plate 3 constitute the main part of the reaction cavity, and the gas inlet cavity is detachably connected to the main part of the reaction cavity, which is convenient for disassembly and maintenance. In other embodiments, the outer ring and the barrel part of the main cover body can also be arranged in an integrated structure, and at this time the outer ring cannot be disassembled and the inner ring can be disassembled.

[0036] Corresponding connecting holes for connecting bolts are arranged on the fixing flange 14, the outer ring 11 and the mounting flange 102, so that the gas inlet cavity is fixed on the main part of the reaction cavity by bolts. The connecting holes on the fixing flange 14 and the outer ring 11 are bolt holes, and the connecting hole on the mounting flange 102 is a threaded hole 103, so that after the bolt passes through the connecting holes on the fixing flange 14 and the outer ring 11, it is threadedly connected in the threaded hole 103 of the mounting flange 102, thereby achieving fixation, which is simple in structure and convenient to install. In other embodiments, the fixing flange and the outer ring can be separately fixed and connected by bolts, and the outer ring and the mounting flange can be separately connected by bolts. In other embodiments, a thread can be arranged on the inner wall of the center hole of the mounting flange, so that the outer ring is threadedly connected to the center hole of the mounting flange to achieve fixed connection. Correspondingly, the size of the connecting end of the fixing flange and the outer ring can be changed to adapt to the fixed connection of the fixing flange and the outer ring through the matching internal thread and external thread.

[0037] The fixing flange 14 is a ring body, the inner diameter of the fixing flange 14 is the same as the inner diameter of the inner ring 12, the outer diameter of the fixing flange 14 is the same as the outer diameter of the outer ring 11, and the outer diameter of the outer ring 11 is the same as the outer diameter of the mounting flange 102. An upward mounting step is arranged in the center hole of the mounting flange 102, the lower end of the outer ring 11 is arranged in the center hole of the mounting flange 102, the lower end surface of the outer ring 11 abuts against the mounting step, and a first sealing flat gasket 15 is arranged between the mounting step and the lower end surface of the outer ring 11 to form a seal. The inner diameter of the part of the outer ring 11 below the inner step 113 is the same as the inner diameter of the part of the mounting flange 102 below the mounting step.

[0038] The lower end surface of the inner ring 12 abuts on the inner step 113 of the outer ring 11, and the inner diameter of the inner ring 12 is the same as the inner diameter of the portion of the outer ring 11 below the inner step 113. The inner step 113 and the outer step 122 are opposite surfaces, and the portion of the outer wall of the inner ring 12 below the outer step 122 is spaced from the portion of the inner wall of the outer ring 11 above the inner step 113 to form the annular air cavity 19, so that the annular air cavity 19 has two opposite side walls in the radial direction. The portion of the outer wall of the inner ring 12 above the outer step 122 is attached to the inner wall of the outer ring 11. The inner wall of the upper end of the outer ring 11 is further provided with an upwardly directed compression step for forming a compression surface of the outer ring 11 for compression by the compression cover 13, and the upper end surface of the inner ring 12 is used to form a compression surface of the inner ring 12 for compression by the compression cover 13. The sealing gasket on the compression surface is the second sealing flat gasket 16. The outer diameter of the compression cover 13 is adapted to the portion of the inner wall of the outer ring 11 above the compression step, and the lower side surface of the compression cover 13 is in sealing engagement with the compression surfaces of the outer ring 11 and the inner ring 12 through the second sealing flat gasket 16. The upper side of the compression cover 13 is further provided with a third sealing flat gasket 17, which seals the upper side surface of the compression cover 13 from the fixed flange 14. The second sealing flat gasket 16 and the third sealing flat gasket 17 form a double sealing structure to ensure reliable sealing. After the fixed flange 14, the outer ring 11, and the mounting flange 102 are fixedly connected by bolts, the sealing flat gaskets are compressed.

[0039] The inner ring 12 and the outer ring 11 are precisely fitted, the compression cover 13 cooperates with the inner ring 12 and the outer ring 11 to form the central cavity 110, and the inner ring 12 and the outer ring 11 are provided with compression surfaces cooperating with the compression cover 13. The outer wall of the end portion of the inner ring 12 away from the side on which the reaction platform is located cooperates with the inner wall of the outer ring 11 to form a sealing groove in communication with the compression surface, and a sealing ring 18 is arranged in the sealing groove. When the compression cover 13 compresses the inner ring 12 and the outer ring 11, the sealing ring 18 is compressed in the sealing groove to form a seal. The outer edge of the upper end surface of the inner ring 12 is provided with a chamfer structure, which cooperates with the inner wall of the outer ring 11 to form a sealing groove with a triangular cross section. The inner and outer side edges of the groove opening of the sealing groove are respectively in communication with the compression surface of the inner ring 12 and the compression surface of the outer ring 11. After the compression cover 13 is compressed and fixed, the compression cover 13 compresses the second sealing flat gasket 16, the second sealing flat gasket 16 compresses the sealing ring 18, and the sealing ring 18 is in sealing cooperation with the inner ring 12 and the outer ring 11. The second sealing flat gasket 16 cooperates with the sealing ring 18 to form a double sealing structure to ensure air tightness. In other embodiments, the sealing groove can also be a rectangular groove. In other embodiments, the sealing ring and the sealing groove at this position can not be provided, and only the second sealing flat gasket is relied on to form a seal.

[0040] The annular air cavity 19 formed by the outer ring 11 and the inner ring 12 has a rectangular cross section, the air inlet hole 112 and the air distribution hole 121 are both circular holes and through holes, the air inlet hole 112 penetrates the outer ring 11 radially, the air inlet hole 112 constitutes an air inlet for the external gas inlet pipeline, the air distribution hole 121 is a through hole penetrating the inner wall and the outer wall of the inner ring 12, the air inlet hole 112 is arranged on the part of the outer ring 11 above the inner step 113, the air distribution hole 121 is arranged on the part of the inner ring 12 below the outer step 122, the air inlet hole 112, the annular air cavity 19, and the air distribution hole 121 penetrate radially, the diameter of the air inlet hole 112 is larger than the diameter of the air distribution hole 121, which is conducive to smooth air intake. In other embodiments, the diameter of the air inlet hole can be the same as the diameter of the air distribution hole, and the air inlet hole and the air distribution hole are arranged staggered.

[0041] The dimension of the annular air cavity 19 in the axial direction of the inner ring 12 is much larger than the dimension of the air distribution hole 121 in the axial direction of the inner ring 12, that is, the diameter of the air distribution hole 121, which is conducive to gas mixing in the annular air cavity 19. In other embodiments, the dimension of the annular air cavity in the axial direction of the inner ring can also be the same as the diameter of the air distribution hole, and the air inlet hole and the air distribution hole are staggered.

[0042] The dimension of the annular air cavity 19 in the axial direction of the outer ring 11 is larger than the dimension of the air inlet in the axial direction of the outer ring 11, that is, the diameter of the air inlet hole 112 is relatively small compared to the upper and lower dimensions of the annular air cavity 19, which facilitates the flow of gas into the annular air cavity 19 and diffusion. In other embodiments, the dimension of the annular air cavity in the axial direction of the outer ring can also be equal to the dimension of the air inlet in the axial direction of the outer ring.

[0043] The air distribution hole 121 is provided with a plurality of circumferential air distribution holes 121 on the inner ring 12, each air distribution hole 121 is circumferentially distributed, and the center lines of each air distribution hole 121 are coplanar, and the gas flow from each air distribution hole 121 can be opposite, thereby forming a second mixing in the central cavity 110, which is conducive to uniform mixing. In other embodiments, the center lines of each air distribution hole can also not be coplanar, and the center lines of the circumferentially adjacent two air distribution holes are staggered.

[0044] The outer wall of the outer ring 11 is provided with an air inlet interface 111 for connecting the external gas inlet pipeline, the air inlet interface 111 corresponds to the air inlet hole 112, the air inlet hole 112 has one, the air inlet interface 111 penetrates the air inlet hole 112 and forms a stepped hole structure, the diameter of the air inlet interface 111 is larger than the diameter of the air inlet hole 112, so as to facilitate the connection of the pipeline.

[0045] The above structure guarantees smooth special gas intake, reasonable intake direction and uniformity of the mixed gas, which will help to improve the synthesis quality and efficiency of single crystal diamond and improve the morphology of the plasma ball. The corresponding parts constitute a complete top cover through mechanical connection, which does not involve welding and special angle hole machining for manufacturing, and the required structure and flow channel are formed by mechanical connection and sealing, which improves the machinability and avoids the problems of machining difficulty and insufficient machining precision caused by welding and narrow space machining. The gas inlet channel of the top cover will be blocked and contaminated due to cavity cleaning or impurity deposition during later use, and the parts of the top cover are mechanically connected, which is simple and fast to install and disassemble, and is convenient for cleaning and maintenance during later use. The mechanical connection of the top cover adopts a sealing flat gasket with high sealing efficiency for sealing, which guarantees the airtightness and safety of the sealing part near the special gas flow channel, avoids affecting the safety of the equipment and the airtightness of the equipment, and helps to ensure that the special gas enters the cavity without leakage and that the external air does not invade the cavity to cause pollution.

[0046] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments without creative labor, or replace some technical features with equivalents. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A chemical vapor deposition apparatus comprising a reaction chamber and a reaction stage disposed in the reaction chamber, the reaction chamber comprising a gas inlet chamber for connecting an external gas inlet line, the gas inlet chamber having a central cavity communicating with a space in which the reaction stage is disposed, the gas inlet chamber being provided with a gas inlet passage for the passage of a reaction gas in the gas inlet line into the central cavity, characterized in that the gas inlet passage is provided with a valve member which is movable between a first position in which the gas inlet passage is closed and a second position in which the gas inlet passage is open. The inner wall of the inner ring is used to form at least part of the inner wall of the central cavity, the intake passage comprises an annular air cavity surrounded by the outer wall of the inner ring and the inner wall of the outer ring, and the gas distribution hole and the gas inlet, the gas inlet is communicated with the annular air cavity to allow the reaction gas to enter the annular air cavity, and the gas distribution hole is communicated with the annular air cavity and the central cavity.

2. The chemical vapor deposition apparatus according to claim 1, wherein The size of the annular air cavity in the axial direction of the inner ring is greater than the size of the gas distribution hole in the axial direction of the inner ring.

3. The chemical vapor deposition apparatus according to claim 1 or 2, characterized by, The size of the annular air cavity in the axial direction of the outer ring is greater than the size of the gas inlet in the axial direction of the outer ring.

4. The chemical vapor deposition apparatus according to claim 1 or 2, wherein The gas distribution hole is provided with a plurality of circumferential gas distribution holes, and the center lines of the gas distribution holes are coplanar.

5. The chemical vapor deposition apparatus according to claim 1 or 2, wherein The inner wall of the outer ring is provided with an inner step, the end of the inner ring abuts on the inner step, the outer wall of the inner ring is provided with an outer step, and the outer step is opposite to the inner step in the axial direction of the inner ring to form the annular air cavity between the outer step and the inner step.

6. The chemical vapor deposition apparatus according to claim 5, wherein The intake cavity comprises a gland for cooperating with the inner ring and the outer ring to form the central cavity, the gland presses the inner ring against the inner step, the inner ring and the outer ring are provided with pressing surfaces matched with the gland, and the pressing surfaces are provided with sealing pads for being pressed by the gland to form a seal.

7. The chemical vapor deposition apparatus according to claim 1 or 2, wherein The intake cavity comprises a gland for cooperating with the inner ring and the outer ring to form the central cavity, the inner ring and the outer ring are provided with pressing surfaces matched with the gland, the end of the inner ring away from the reaction platform is provided with an outer wall, the outer wall and the inner wall of the outer ring form a sealing groove connected with the pressing surface, and a sealing ring is arranged in the sealing groove.

8. The chemical vapor deposition apparatus according to claim 1 or 2, wherein The outer ring is provided with a radial gas inlet hole, the gas inlet hole constitutes the gas inlet, and the gas distribution hole is a through hole penetrating the inner wall and the outer wall of the inner ring.

9. The chemical vapor deposition apparatus according to claim 1 or 2, wherein The reaction cavity comprises a top cover and a main body part for cooperating with the top cover to form an internal space of the reaction cavity, the top cover comprises a main cover body and the intake cavity, the intake cavity is detachably connected to the main cover body, and the main cover body is fixed to the main body part of the reaction cavity.

10. The chemical vapor deposition apparatus of claim 9 wherein, The intake cavity comprises a gland for cooperating with the inner ring and the outer ring to form the central cavity, and a fixing flange for pressing the gland against the inner ring and the outer ring, the main cover body is provided with a mounting flange matched with the outer ring, and the fixing flange, the outer ring and the mounting flange are provided with corresponding connecting holes for connecting bolts to fix the intake cavity to the main cover body by the bolts.

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